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  • 201.
    Neumann, Liselotte
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Linking growth and vitality in large Quercus robur to environmental factors and predicting their future in Linköping municipality2018Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Veteran trees such as large Quercus robur L. function as biodiversity hotspots and provide a number of valuable ecological functions. This study aimed to increase knowledge about the mechanisms that influence the longevity of Q. robur by: (i) describing the status of veteran Q. robur in Linköping municipality, (ii) describing findings of valuable lichens among these trees, (iii) examine whether land use, nature type, crown layer closure, land management, or overgrowth of brushwood or forest in 2018 or an earlier year could explain girdle growth or crown vitality in Q. robur, and (iv) predict the future population of veteran Q. robur. Data was collected from 51 Q. robur with a circumference larger than 450 cm in April 2018 in Linköping municipality, Sweden. Out of these, 28 individuals could be compared to data from a previous inventory. These were the basis for statistical analyses of correlations between environmental factors, growth and crown vitality. Generally, most Q. robur individuals were standing in pastures, had high crown vitality, had a low amount of overgrowth of brushwood or forest around them, and many of them hosted indicator lichens. The main correlation found was between crown vitality and overgrowth of brushwood. The girdle growth was 1.81 cm year-1 and the mortality was 0.18 % year-1 on average. Based on these growth and mortality numbers, and data from other studies, the future population of veteran Q. robur was predicted to increase from 471 to 2996 individuals in the area in the next 100 years (1615-3433 pcs).

  • 202.
    Nilsson, Alexander
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Tillväxthastighet och storleksfördelning hos hassel (Corylus avellana)2013Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    To increase the knowledge about the growth of hazel (Corylus avellana)and size distribution of the shoots, circumference and stem diameter wasmeasured in a total of 54 clones in two areas in Östergötland. Further, thewidth of growth rings was determined for separate years. The diameter ofthe stems was measured both out from the centre of the stem andperpendicular to the first measure. The stems showed only a weaktendency to have an oval shape (with the longest side outwards from thecentre). The growth model did not improve when the degree of sunlightof clones was taken into the account. Therefore it is possible to use asimple and general growth model for the shoots of hazel. Such a modelwas then used to estimate the age of hazel from the diameter of the clone.

  • 203.
    Nilsson, Alexander
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Trapped in the forest: The longhorn beetle Tragosoma depsarium L. in south-east Sweden2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The rare and elusive wood-living beetle Tragosoma depsarium, once widespread all over Sweden, is associated with large, sun-exposed pine logs required for breeding. Due to modern forestry and fire suppression, this type of substrate has become so rare in the landscape that the beetles’ existence in Sweden is threatened. Recently, the female sex pheromone of this species was synthesised, providing a new method to monitor beetle populations using pheromone traps. Such a method was used in the current study to relate the presence-absence of T. depsarium with different landscape variables at different scales; 100, 500, 1000 and 2000 meters, respectively. The occurrence of T. depsarium in Östergötland County was associated with the amount of protected areas and clear-cuts at 500 and 1000 meters, respectively. Additionally, the amount of pine forest within 2000 m from the trap showed a weak, positive effect on the number of beetles. In the whole south-east boreo-nemoral zone of Sweden, a positive correlation between beetle occurrence and protected areas were found at 2000 m together with a negative correlation for volume pine wood within 100 m. Also, emergence holes on pine logs around each trap were strongly associated with beetle occurrences. To conclude, using pheromone traps were an easy way of detecting beetles. Although the number of caught T. depsarium varied greatly over time, the sampling period matched the flight period well. For long-term survival of this beetle, the forests must contain breeding substrates and be opened up through prescribed burning, selective cutting and active forestry.

  • 204.
    Norén, Hanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Exposure to the antidepressant fluoxetine reduces mating behaviour in the freshwater isopod Asellus aquaticus2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Worldwide, pharmaceutical compounds continue to increase in our aquatic environment. The predominant route into nature is through wastewater treatment plants since the elimination of residual pharmaceuticals is still not mainstream in WWTPs. Fluoxetine is an antidepressant which is commonly prescribed to treat human depression. Wastewater residual fluoxetine is typically found in waters around the world, and can thus affect exposed organisms, such as fish and invertebrates. However, how fluoxetine may affect mating behaviour in exposed organisms remains poorly understood, and particularly so in invertebrates. This is hampering our understanding of the consequences of our medicine leaking into nature because mating behaviour often affects fitness, and invertebrates are key organisms in food chains. Therefore, I here experimentally investigated long-term effects of environmental relevant concentration of fluoxetine (20 ng L-1) on mating behaviours of male and female freshwater isopod Asellus aquaticus. I demonstrate that fluoxetine reduced male mating attempts with receptive females. Further, there was a tendency for fluoxetine exposure to increase latency to form pre-copula. There was no effect of fluoxetine exposure on male latency to encounter females or female responses toward males. These results indicate that fluoxetine also can affect isopods by reducing mating behaviour. In the long-term, if reproduction is delayed or reduced, it may cause a reduction in populations and thus, alter the whole ecosystem.

  • 205.
    Nygårds, Sofia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ekologi. Linköpings universitet, Tekniska högskolan.
    Importance of habitat quality and landscape factors for a monophagous shield bug on a rare host plant2012Independent thesis Advanced level (degree of Master (Two Years)), 40 poäng / 60 hpOppgave
    Abstract [en]

    Understanding the factors affecting species distribution and at what scale a species respond to these factors is a major challenge in conservation biology. I studied the distribution and abundance of a monophagous shield bug Canthophorus impressus at three spatial scales: host plants, patches and circular landscapes (area ca. 3 km2), to determine the relative importance of the different spatial scales and how habitat quality, amount and spatial configuration affect the distribution of C. impressus. Influence of habitat characteristics on occurrence and abundance of the bug was analysed with separate generalised linear mixed models. The data show that effects of habitat quality and amount dominate over configuration in determining the distribution of C. impressus. The bug prefers large host plants in warm conditions on a plant scale and abundant host plants in a landscape scale, whereas patch scale was not important for the distribution of the bug. Management should aim to preserve sites with abundant host plants and promote large host plants with low to moderate grazing. To secure sufficient number of host plants in the landscape, high densities of suitable habitat such as semi-natural grasslands should be preserved. This study suggests that analyses of multiple spatial scales are crucial for identifying appropriate actions for successful conservation of species living in fragmented habitats.

  • 206.
    Nygårds, Sofia
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Sedimentation av lera och fosfor i en anlagd våtmark2010Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Våtmarker som anläggs på jordbruksmark kan förhindra att fosfor från åkrarna når sjöar och vattendrag och hjälper därmed till att minska övergödningen. Det är viktigt att utforma våt-marken på ett sådant sätt att så mycket som möjligt av den biotillgängliga fosforn hålls kvar. Syftet med studien var att undersöka om det finns ett positivt samband mellan lerinnehåll och fosfors biotillgänglighet i en anlagd våtmarks sediment. Syftet var även att undersöka om partikelstorleken minskar gradvis med avståndet från inloppet, det vill säga om mer lera sedimenterar närmare utloppet. Prover togs längs tre transekter från sedimentet i en våtmark i västra Östergötland och fosfor- samt partikelstorleksanalyser gjordes. Genom extraktion med ammoniumklorid (NH4Cl) kunde lättillgänglig fosfor bestämmas. Partikelstorleksanalysen gjordes med en modifierad pipettmetod, baserad på att större partiklar sedimenterar fortare än mindre partiklar. Regressionsanalys visade att partikelstorleken minskade signifikant från inlopp till utlopp i våtmarken. Däremot hittades inte några signifikanta samband mellan partikelstorlek och lättillgänglig fosfor eller totalfosfor, i motsats till resultat i andra studier. Halterna av både lera och olika fosforfraktioner i sedimentet var relativt låga och likartade vid olika provpunkter i våtmarken vilket kan ha påverkat resultaten.

  • 207.
    Odhiambo, Moses
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Routh, Joyanto
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Does Black Carbon Contribute to Eutrophication in Large Lakes?2016Inngår i: Current Pollution Reports, ISSN 2198-6592, Vol. 2, nr 4, s. 236-238Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Eutrophication is a major ecological crisis in water bodies. This is mainly driven by anthropogenic activities in the catchment that incorporate various nutrients. Input of nutrients can also be driven by atmospheric deposition, which has a large footprint that goes beyond local point source(s). In particular, black carbon (BC) can be a carrier of various nutrients and increase primary productivity in lakes. We need to monitor the input of BC in large water bodies to fully understand its role in driving primary productivity and change in trophic status.

  • 208.
    Ohlsson, Mikael
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Finns det anpassningar beroende på födokällor hos olika ekotyper av Asellus aquaticus?2016Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    The freshwater isopod Asellus aquaticus has been shown to exist in two different ecotypes, stonewort ecotypes and reed ecotypes. The differentiation is likely due to adaptation towards different predator regimes and possibly also other selective forces. It is unknown if the ecotypes have different adaptations when it comes to food preferences and roles in the ecosystems. In the present study, isopods of each ecotype were collected from two lakes where the differentiation of pigmentation was especially pronounced to examine whether this had a connection with other physiological adaptations. Growth rate, competitiveness, exposing behaviour and grazing efficiency were tested in two experiments with periphyton or coarse detritus as food sources. None of the results indicated a specialization towards their regular food. Instead, the stonewort ecotype had significantly faster growth rate for both food sources. Presence of snails caused a slight, but statistically insignificant increase in growth rate when periphyton was the food source. Individuals of the reed ecotype were more exposed on the substrate than the stonewort ecotype, but the difference was not statistically significant. Grazing efficiency of both detritus and periphyton was similar and not significantly different between ecotypes. The results thus show no indication to phenotypical differences between ecotypes in the ability to graze or process different types of food. However, currently known adaptations, e.g. in behaviour and pigmentation may be important for the ecological role of the species.

  • 209.
    Orsholm, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    The effect of temperature on productivity of birds in Sweden and Finland2019Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Anthropogenic climate change is one of the most important factors influencing population growth and survival. Therefore, to be able to predict the effect of climate change on ecosystem composition and function, it is important to understand its effect on demographic variables, such as productivity. As a measure of productivity, I related the proportion of yearling birds captured during bird ringing in southern Sweden with mean temperature during the breeding season. I then compared the relationship between temperature and productivity for species with different traits regarding number of broods produced per season, thermal niches and migration behaviours. For most species (72%), productivity positively related to temperature during the breeding season. The relationship was strongest for species with the ability to vary the number of broods per year and species with a warmer thermal niche, whereas there was no difference between long-distance migratory and short-distance migratory species. The results suggest that, for some bird species in the study area, climate warming can increase population sizes. However, long-term effects of climate change may be different than the interannual fluctuations of temperature considered in this study, especially when interacting effects of habitat losses are taken into account.

  • 210.
    OSAFO, NANA
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Phosphorus in the sediment of L. Hällerstadsjön: spatial distribution, fractions and release to the water volume2016Independent thesis Advanced level (degree of Master (Two Years)), 40 poäng / 60 hpOppgave
    Abstract [en]

    : In freshwater systems phosphorus (P) is the limiting element in the cause of eutrophication. In many Swedish lakes, causes of eutrophication have been attributed to more of internal loading than external since the external loading has been fairly well managed. Internal loading is linked to the mobility of sediment P, which are known to be Bioavailable P (BAP). Sediments from Lake Hällerstadsjön in Sweden was studied to know the BAP concentration and its possible release into the water column under reduced conditions. Sediments were sampled at two different depths, 0-5 cm and 5-10cm. BAP was determined by a phosphorus fractionation scheme. Sediments were incubated under oxic and anoxic conditions in the laboratory to evaluate sediment P release. Spatial variation in the distribution of P forms across the lake was also studied, in order to examine possible local patterns, particularly along a transect from the main inlet to the outlet. Fractionation analyses showed a trend of; Residual-P > NaOH-P > HCl-P > BD-P > Loosely bound P. The fractions constituting the BAP was higher at the 0-5 cm sediment depth than 5-10 cm. Sediment P flux was recorded for anoxic but not oxic sediment. BAP correlated significantly with sediment P flux (P= 0.01). Spatially, the P distribution varied both at depths and along a latitudinal transect, from the main inlet to the outlet. 

    Dredging of the surface sediments with high BAP content would possibly be an effective means of preventing eutrophication of the lake.

  • 211.
    Pace, Michael L.
    et al.
    Institute of Ecosystem Studies, Millbrook, New York, USA.
    Cole, Jonathan J.
    Institute of Ecosystem Studies, Millbrook, New York, USA.
    Carpenter, Stephen R.
    Center for Limnology, University of Wisconsin, Madison, Wisconsin, USA.
    Kitchell, James F.
    Center for Limnology, University of Wisconsin, Madison, Wisconsin, USA.
    Hodgson, James R.
    Department of Biology, St. Norbert College, De Pere, Wisconsin, USA.
    Van de Bogert, Matthew C.
    Institute of Ecosystem Studies, Millbrook, New York, USA.
    Bade, Darren L.
    Center for Limnology, University of Wisconsin, Madison, Wisconsin, USA.
    Kritzberg, Emma S.
    Department of Ecology/Limnology, Lund University, Lund, Sweden.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Whole-lake carbon-13 additions reveal terrestrial support of aquatic food webs2004Inngår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 427, nr 6971, s. 240-243Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ecosystems are supported by organic carbon from two distinct sources. Endogenous carbon is produced by photosynthesis within an ecosystem by autotrophic organisms. Exogenous carbon is produced elsewhere and transported into ecosystems. Consumers may use exogenous carbon with consequent influences on population dynamics, predator-prey relationships and ecosystem processes(1). For example, exogenous inputs provide resources that may enhance consumer abundance beyond levels supported by within-system primary production(2). Exogenous fluxes of organic carbon to ecosystems are often large, but this material is recalcitrant and difficult to assimilate, in contrast to endogenously produced organic matter, which is used more easily(3,4). Here we show, by the experimental manipulation of dissolved inorganic C-13 in two lakes, that internal primary production is insufficient to support the food webs of these ecosystems. Additions of NaH (CO3)-C-13 enriched the C-13 content of dissolved inorganic carbon, particulate organic carbon, zooplankton and fish. Dynamics of C-13 indicate that 40-55% of particulate organic carbon and 22-50% of zooplankton carbon are derived from terrestrial sources, showing that there is significant subsidy of these ecosystems by organic carbon produced outside their boundaries.

  • 212.
    Persson, Alexandra
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Environmental Impact Assessments in Detailed Development Plan Processes: An Adequacy Analysis2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    A detailed development plan (DDP) is a legally binding plan that regulates the municipalities land use on a detailed level. The purpose with the DDP is to evaluate the suitability for development on land access, in order for municipalities to manage spatial planning and minimize environmental harm. If a DDP would likely cause a significant impact on the environment, an Environmental Impact Assessment (EIA) has to be produced.

    The aim of this thesis was to investigate how DDP and EIA processes are working on a local level in Sweden, and how the quality is reflected in the processes. More specifically, I investigated the role of EIA actors involved in the DDP process, as well as whether these processes are inadequate from an environmental conservation perspective. To investigate these issues, a document study was conducted as well as an interview study.

    The results from the study presents several shortcomings in both processes; examples of shortcomings were the lacking knowledge among the DDP and EIA actors in how to conduct the process, as well as interpreting and understanding the law.  Other observed shortcomings were the different levels of engagement among the plan administrators, the EIA performers and the County Administrative Board reviewers. Three important factors were recognized for achieving good processes. Firstly, the people involved need to have broad knowledge and good qualifications. Secondly, the actors must be able to communicate in a good and clear manner. Lastly, the third factor is a good process leader who brings together the DDP and EIA process.

  • 213.
    Petersen, Rebecca
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Mellanspettens förutsättningar för återintroduktion i Linköping: Med fokus på krav på kvalitet och storlek samt avstånd mellan habitat.2019Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Humans have a large impact on biodiversity, especially by causing habitat loss and habitat degradation but also through human-induced climate change. Because of habitat loss and habitat degradation the Middle-spotted woodpecker (Dendrocopos medius) went extinct in Sweden 1983. Globally the Middle-spotted woodpecker is today listed as least concern but because of human-induced climate change the species might be threatened in the whole world in the future. Different ways to help the species is by protection of potential habitat, restoration or reintroduction. The aim of this study is to help the Middle-spotted woodpecker survive in the future by facilitate its potential progress to Sweden, Linköping. One way to help the species is by investigating if a reintroduction is possible. Therefore, I created a habitat model of the Middle-spotted woodpecker based on published studies and used the model to analyze the landscape for possible sites of reintroduction. Results from published studies showed that the species require at least 20 hectares oak forest per breeding pair, a high density of mature oak and more potential habitat to distribute to, within a 10-kilometer distance. Four areas in Linköping fulfilled all the requirements but only two of them were situated in less than 10 kilometers from each other. A successful reintroduction of the Middle-spotted woodpecker requires a landscape with at least 15-20 potential habitat in a near distance to each other. Therefore, a reintroduction of Middle-spotted woodpecker is not possible in Linköping unless more habitats is restored.  

  • 214.
    Pettersson, Elin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Vilken preferens har tjockskalig målarmussla (Unio crassus) för bottensubstrat och vattenhastighet i Storån, Östergötland?2012Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    The thick shelled river mussel (Unio crassus) has a fragmented distribution in southern Sweden. It is a threatened and protected species. In both the Swedish red list and the IUCN Red List of Threatened Species Unio crassus is classified as Endangered (EN). Causes for this classification are for instance differentiated bottom substrate and deterioration in water quality. In this study, habitat preferences of Unio crassus were investigated to assist in future restoration work. The environmental parameters that were used to characterize the habitat in sites with or without Unio crassus were water depth, bottom substrate, water velocity, slope, and shading. In this thesis I focused in bottom substrate and water velocity. Sites with Unio crassus had finer bottom substrate and lower water velocity than sites without (t>2.54, p<0.05, t-test). Most of the sites with Unio crassus had a bottom substrate with a size <4 mm and a water velocity around 0.3-0.5 m/s. These two variables were correlated with each other. When the water velocity was higher, the bottom substrate was coarser. These results are in line with other studies, showing that if the bottom substrate is either too coarse or too fine, it could impact Unio crassus. Too coarse bottom substrate probably results in difficulty in burrowing and too fine most likely results in interfering with respiration and feeding. Earlier studies indicate that the water velocity can have a greater impact on unionids than bottom substrate. Because of the correlation between bottom substrate and water velocity it is not easy to disentangle the importance of each factor.

  • 215.
    Pettersson, Elin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Vilken preferens har tjockskalig målarmussla (Unio crassus) för bottensubstrat och vattenhastighet i Storån, Östergötland?2012Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    The thick shelled river mussel (Unio crassus) has a fragmented distribution in southern Sweden. It is a threatened and protected species. In both the Swedish red list and the IUCN Red List of Threatened Species Unio crassus is classified as Endangered (EN). Causes for this classification are for instance differentiated bottom substrate and deterioration in water quality. In this study, habitat preferences of Unio crassus were investigated to assist in future restoration work. The environmental parameters that were used to characterize the habitat in sites with or without Unio crassus were water depth, bottom substrate, water velocity, slope, and shading. In this thesis I focused in bottom substrate and water velocity. Sites with Unio crassus had finer bottom substrate and lower water velocity than sites without (t>2.54, p<0.05, t-test). Most of the sites with Unio crassus had a bottom substrate with a size <4 mm and a water velocity around 0.3-0.5 m/s. These two variables were correlated with each other. When the water velocity was higher, the bottom substrate was coarser. These results are in line with other studies, showing that if the bottom substrate is either too coarse or too fine, it could impact Unio crassus. Too coarse bottom substrate probably results in difficulty in burrowing and too fine most likely results in interfering with respiration and feeding. Earlier studies indicate that the water velocity can have a greater impact on unionids than bottom substrate. Because of the correlation between bottom substrate and water velocity it is not easy to disentangle the importance of each factor.

  • 216.
    Pettersson, Helene
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Understanding of human communicative motives in domestic dogs2009Independent thesis Advanced level (degree of Master (Two Years)), 40 poäng / 60 hpOppgave
    Abstract [en]

    I investigated the understanding of human communicative motives in domestic dogs. Dogs use human communicative cues, like the pointing gesture when searching for hidden food, but it is uncertain how dogs interpret human communication. 32 dogs were presented with two communicative contexts in an object choice task experimental design. In a cooperative context the experimenter informed the subject where food was hidden by pointing and giving a verbal indication. In a competitive context the experimenter held out her arm towards the correct location in a stop gesture and firmly said no. To be successful in the competitive context the subject had to understand the experimenters communicative motive and make an inference from the prohibition (i.e. she would only prohibit it if there was something good there). The average correct choices were compared between the conditions. The dogs successfully followed the cooperative communication. They showed a trend towards choosing the baited cup in the competitive condition. A second study tested if the stop gesture affected the dogs’ choice, since it is not known how dogs interpret gestures. The pointing cue was now presented with the prohibiting command and the stop gesture was presented with the cooperative verbal cue. The dogs used the cooperative communication but did not understand the competitive context. A difference between the contexts was found. The dogs did not differentiate between the gestures. In conclusion dogs do not make inferences from competitive communication or prohibition but are specialized in utilizing cooperative communication

  • 217.
    Pettersson, Kristina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ekologi.
    Frivilliga avsättningar i gröna skogsbruksplaner - en fallstudie av sex skogsfastigheter samt en enkätundersökning i Östergötland2009Independent thesis Advanced level (degree of Master (One Year)), 30 poäng / 45 hpOppgave
    Abstract [sv]

    Frivilliga avsättningar av skog med höga naturvärden är en viktig del för att nå Miljömålet ”Levande skogar”. Det finns dock tveksamheter om de naturvårdsbiologiska kvalitéerna i dessa avsättningar. Syftet med denna studie var därför att undersöka om den skog som avsätts frivilligt av privata skogsägare är den skogsmark som har de högsta naturvärdena på fastigheten. Vidare studerades också markägarens naturvårdskunnande, utbildningsnivå och attityd till naturvård. Detta kan påverka viljan att avsätta skog frivilligt, hur långsiktig avsättningen blir samt kvalitén på avsättningarna. Studien består av inventeringar på sex skogsfastigheter i Östergötland med frivilliga avsättningar, samt en enkätstudie till skogsägare. Det visade sig att skogsägarna i huvudsak avsatte de bestånd med högst naturvärde på fastigheten. Tre bestånd (en lövskog, en tallskog samt en källmiljö) av totalt 59 hyste högre naturvärde än de frivilligt avsatta. De avsatta skogarnas hade lägre virkestäthet än produktionsbestånden och bestod i större utsträckning av lövskog. Majoriteten av skogsägarna avsatte skogen långsiktigt för kommande generationer. När skogsägarna fick rangordna syftet med sin skogsfastighet prioriterades virke i första hand, naturvård värderades betydligt lägre. En mätning av kunskaper i tillämpad ekologi och artkännedom visade att skogsägarnas kunskaper i regel var bristfälliga när det gällde igenkänning av indikatorarter samt viktiga trädslag för artbevarande. Majoriteten av de som var negativa till att göra frivilliga avsättningar kunde tänka sig att ändra åsikt vid ”skälig ersättning”. Mer omfattande studier behövs för att avgöra om mina resultat var representativa och om de frivilliga avsättningarna verkligen hyser fastighetens högsta naturvärden och lever upp till miljömålet levande skogar.

  • 218.
    Pettersson, Rickard
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Structural variation across food webs as a measure of biodiversity at the ecosystem level2013Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Biodiversity can be measured in several ways and on several levels. In this study a framework is developed to use topological differences in the food webs describing ecosystems to quantify differences between ecosystems. This is then used in an attempt to describe biodiversity at the ecosystem level. Empirical food webs were analysed to find out if distance between systems in a multidimensional space where network characteristics are used as axes can be used to give an indication of variation among the systems. To test if some class of systems is more varied the systems were classified in several ways, according to type of system, location of system and size of the food web describing the system. Among the analysed systems some classes had a larger proportion of large distances, which indicates that there were more dissimilar systems within those classes. The classes showing larger variation were lakes, freshwater systems, temperate systems and systems with a larger number of nodes.

  • 219.
    Poelstra, J. W.
    et al.
    Uppsala University, Sweden.
    Vijay, N.
    Uppsala University, Sweden.
    Hoeppner, M. P.
    Linköpings universitet. Uppsala, Sweden.
    Wolf, J. B. W.
    Uppsala University, Sweden; Science Life Lab, Sweden.
    Transcriptomics of colour patterning and coloration shifts in crows2015Inngår i: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 24, nr 18, s. 4617-4628Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Animal coloration is one of the most conspicuous phenotypic traits in natural populations and has important implications for adaptation and speciation. Changes in coloration can occur over surprisingly short evolutionary timescales, while recurrence of similar colour patterns across large phylogenetic distances is also common. Even though the genetic basis of pigment production is well understood, little is known about the mechanisms regulating colour patterning. In this study, we shed light on the molecular elements regulating regional pigment production in two genetically near-identical crow taxa with striking differences in a eumelanin-based phenotype: black carrion and grey-coated hooded crows. We produced a high-quality genome annotation and analysed transcriptome data from a 2 3 2 design of active melanogenic feather follicles from head (black in both taxa) and torso (black in carrion and grey in hooded crow). Extensive, parallel expression differences between body regions in both taxa, enriched for melanogenesis genes (e.g. ASIP, CORIN, and ALDH6), indicated the presence of cryptic prepatterning also in all-black carrion crows. Meanwhile, colour-specific expression (grey vs. black) was limited to a small number of melanogenesis genes in close association with the central transcription factor MITF (most notably HPGDS, NDP and RASGRF1). We conclude that colour pattern differences between the taxa likely result from an interaction between divergence in upstream elements of the melanogenesis pathway and genes that provide an underlying prepattern across the body through positional information. A model of evolutionary stable prepatterns that can be exposed and masked through simple regulatory changes may explain the phylogenetically independent recurrence of colour patterns that is observed across corvids and many other vertebrate groups.

  • 220.
    Price-Rees, Samantha J.
    et al.
    University of Sydney, Australia.
    Lindström, Tom
    University of Sydney, Australia.
    Brown, Gregory P.
    Shine, Richard
    The effects of weather conditions on dispersal behaviour of free-ranging lizards (Tiliqua, Scincidae) in tropical Australia2014Inngår i: Functional Ecology, Vol. 28, nr 2, s. 440-449Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Summary Animals may switch between alternative modes of movement (e.g. philopatry vs. dispersal) in response to complex interactions between internal state, landscape characteristics, dispersal capacity and navigational capacity. In this study, we use an extensive data set from GPS telemetry of free-ranging lizards (bluetongue skinks, Tiliqua spp.) in the Australian wet-dry tropics, to examine how abiotic conditions (temperature, air pressure, precipitation, humidity and wind speed) influence lizard dispersal. The GPS transmitters provided >60,000 records of lizard location from 49 individuals (41 T. scincoides intermedia, 8 T. multifasciata) monitored for a mean of 65 days each. We used a maximum likelihood analytical tool to objectively distinguish intra-patch movements from dispersive movements. Threshold levels of dispersal to differentiate between these two movement phases averaged 36–42 m displacement per hour, depending on species and site. Whether bluetongue lizards within the study population dispersed (rather than remained encamped) was highly associated with weather variables, notably air temperature and atmospheric pressure. Fine-scale (hourly) weather conditions were better predictors of lizard dispersal than daily mean values. Lizards primarily dispersed between widely scattered patches of core-habitat under fine, hot, clear weather conditions. Air pressure tended to predict lizard dispersal more accurately than did more commonly analysed variables such as temperature and precipitation.

  • 221.
    Quinn, Laura
    et al.
    North-West University, South Africa.
    Polder, Anuscka
    Veterinary Institute, Norway.
    Roos, Claudine
    North-West University, South Africa.
    Kylin, Henrik
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Løken, K
    Veterinary Institute, Norway.
    Skaare, Janneche Utne
    Veterinary Institute, Norway.
    Pieters, Rialet
    North-West University, South Africa.
    Bouwman, Henk
    North-West University, South Africa.
    Levels and Implications of Persistent Organic Pollutants and Other Contaminants in South Africa. Results from the "LIPOPSA" Project2011Konferansepaper (Annet vitenskapelig)
  • 222.
    Rael, Rosalyn C.
    et al.
    Univ Michigan, MI 48109 USA; Tulane Univ, LA 70118 USA.
    D'Andrea, Rafael
    Univ Michigan, MI 48109 USA; Univ Illinois, IL 61801 USA.
    Barabas, György
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten. Univ Michigan, MI 48109 USA.
    Östling, Annette
    Univ Michigan, MI 48109 USA.
    Emergent niche structuring leads to increased differences from neutrality in species abundance distributions2018Inngår i: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 99, nr 7, s. 1633-1643Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Species abundance distributions must reflect the dynamic processes involved in community assembly, but whether and when specific processes lead to distinguishable signals is not well understood. Biodiversity and species abundances may be shaped by a variety of influences, but particular attention has been paid to competition, which can involve neutral dynamics, where competitor abundances are governed only by demographic stochasticity and immigration, and dynamics driven by trait differences that enable stable coexistence through the formation of niches. Key recent studies of the species abundance patterns of communities with niches employ simple models with pre-imposed niche structure. These studies suggest that species abundance distributions are insensitive to the relative contributions of niche and neutral processes, especially when diversity is much higher than the number of niches. Here we analyze results from a stochastic population model with competition driven by trait differences. With this model, niche structure emerges as clumps of species that persist along the trait axis, and leads to more substantial differences from neutral species abundance distributions than have been previously shown. We show that heterogeneity in between-niche interaction strength (i.e., in the strength of competition between species in different niches) plays the dominant role in shaping the species abundances along the trait axis, acting as a biotic filter favoring species at the centers of niches. Furthermore, we show that heterogeneity in within-niche interactions (i.e., in the competition between species in the same niche) counteracts the influence of heterogeneity in between-niche interactions on the SAD to some degree. Our results suggest that competitive interactions that produce niches can also influence the shapes of SADs.

  • 223.
    Rahm, Lars
    et al.
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Humborg, C.
    Smedberg, E.
    Mörth, M.
    Danielsson, Åsa
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Dissolved silicate dynamics in boreal and subarctic rivers - vegetation control over temperature?2006Inngår i: The Silicon Cycle: Human Perturbations and Impacts on aquatic systems / [ed] Venugopalan Ittekkot,Daniela Unger ,Christoph Humborg and Nguyen Tac An, New York: Island Press , 2006, 1, s. 53-69Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Silicon is among the most abundant elements on earth. It plays a key but largely unappreciated role in many biogeochemical processes, including those that regulate climate and undergird marine food webs. The Silicon Cycle is the first book in more than 20 years to present a comprehensive overview of the silicon cycle and issues associated with it. The book summarizes the major outcomes of the project Land-Ocean Interactions: Silica Cycle, initiated by the Scientific Community on Problems of the Environment (SCOPE) of the International Council of Scientific Unions (ICSU). It tracks the pathway of silicon from land to sea and discusses its biotic and abiotic  modifications in transit as well as its cycling in the coastal seas. Natural geological processes in combination with atmospheric and hydrological processes are discussed, as well as human perturbations of the natural controls of the silicon cycle.

  • 224.
    Rapp, Malin
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Betydelsen av bebyggelse, barksprickedjup och solexponering för eklavfloran i Linköpings stad med omnejd2011Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Lichens have long been used as indicators for monitoring air pollution, due to the fact that they are sensitive for changes in air quality. Other factors that influence the lichens growth is sun exposure and substrate age. Several studies in other countries show that the lichen diversity is larger in the outline region of larger cities than in the city center.

        The purpose of this study was to study the effect of urban areas, sun exposure, tree age and tree perimeter on lichen flora. The fieldwork was done on 211 oaks, half of which where located in an urban environment and the other half in a rural environment. In total, 19 species of lichens where studied and half of them where red-listed species or rare, like Chaenotheca phaeocephala, Cliostomum corrugatum and Calicium adspersum. The total number of species and the presence of the specific species were noted. The analysis showed that the majority of the species were negatively affected by the urban environment. The results also show that the occurrence of rare lichen species was higher on older oaks.

  • 225.
    Rinta, Paeivi
    et al.
    University of Bern, Switzerland.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Schilder, Jos
    University of Bern, Switzerland.
    Van Hardenbroek, Maarten
    University of Bern, Switzerland.
    Stoetter, Tabea
    University of Bern, Switzerland.
    Heiri, Oliver
    University of Bern, Switzerland.
    Higher late summer methane emission from central than northern European lakes2017Inngår i: Journal of limnology, ISSN 1129-5767, E-ISSN 1723-8633, Vol. 76, nr 1, s. 52-67Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Quantifying methane (CH4) emissions from lakes is important for regional and global greenhouse gas emission inventories. However, regional and global estimates suffer from methodologically inconsistent data sets and from the situation that systematic flux measurements are presently available only for some regions in the world. In particular, many temperate regions dominated by agricultural land use, like central Europe, lack regional multi-lake studies of lacustrine CH4 emissions. We compare estimates of diffusive and ebullitive flux from 30 small central European and 17 small boreal lakes based on standardized measurements during a single visit per lake in late summer. Furthermore, we assess the amount of CH4 accumulated in the hypoxic deep-water layers in late summer. This provides an estimate of the potential release of CH4 from these lakes during autumn mixing (storage flux). The results show that emissions per unit area of lake surface from central European lakes are significantly higher than those from boreal lakes, with average estimates of diffusive and ebullitive flux being as much as six and 27 times higher, respectively. CH4 concentration in the surface water was significantly related with lake area and maximum depth in the boreal lakes. However, no significant relationships between diffusive and ebullitive fluxes and lake basin morphometry were found in central European or boreal lakes, as proposed in earlier studies, although the short measurement period (6h) may not have been adequate for reliably quantifying ebullition in our study. As expected, storage flux was related to relative depth and relative volume of the hypoxic water layer in both regions. We discuss the relevance of the higher observed diffusive and ebullitive fluxes for regional estimates in central Europe based on an example of previous emission estimates from small lakes in Switzerland. Our results suggest that diffusive and ebullitive CH4 emissions from these lakes may be considerably higher than estimated based on widely applied relationships for predicting lacustrine CH4 emissions developed in northern European and North American regions. The results also confirm that modifications are necessary when applying these relationships to central European lakes. Our study highlights the inter-regional variability in lacustrine CH4 emissions and the need for regionally developed calibration data for validating and developing predictive models for estimating CH4 emissions from lakes at the landscape scale.

  • 226.
    Riskin, Shelby
    et al.
    Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, USA / Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA, USA.
    Small, Gaston
    Department of Biology, University of St. Thomas, USA.
    Mikkelsen, Robert
    IPNI, Western North America Region, California, USA.
    Metson, Genevieve
    Arizona State University, USA.
    Bateman, Anna
    Department of Civil Engineering, University of Birmingham, Edgbaston, Birmingham, UK.
    Cooper, James
    Department of Civil Engineering, University of Birmingham, Edgbaston, Birmingham, UK.
    Hanserud, Ola
    Norwegian Institute for Agricultural and Environmental Research (Bioforsk), Norway.
    Haygarth, Philip
    The Lancaster Environment Centerm, Lancaster University, England, UK.
    Laspoumaderes, Cecilia
    Laboratorio de Limnología, INIBIOMA, CONICET‐UN, Comahue, Bariloche, Argentina.
    McCrackin, Michelle
    Washington State University-Vancouver, Vancouver, WA / National Research Council, Research Associateship Program, Washington DC, USA.
    Remington, Sonya
    School of Stustainability, Arizona State University, Tempe, USA.
    Phosphorus in Urban and Agricultural Landscapes2013Inngår i: Phosphorus, Food, Our Futures / [ed] Karl A. Wyant, Jessica R. Corman, and James J. Elser, Oxford University Press, 2013, s. 86-111Kapittel i bok, del av antologi (Fagfellevurdert)
  • 227.
    Saarinen Claesson, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Fisk- och fågelpredations påverkan på den bentiska makroevertebratfaunans sammansättning under tidig vår i Tåkern2012Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Predation is one of many factors that form the structure of the macroinvertebrate community in lakes, wetlands and watercourses. Earlier studies lack an examination concerning how fish- and waterfowl predation affect macroinvertebrates during shorter periods in the spring. I performed an exclosure study in the shallow eutrophic Lake Tåkern which is located in the western part of Östergötland County, Sweden. The experiment was performed during a three week period (1-21 April 2012) when the water temperature was low and the density of migrating diving ducks was high. The experimental cages used included three out of four different treatments; general predation (open cages), bird exclusion (net with mesh size 90*45mm) and no predation (net with mesh size 1*1mm). In the fourth treatment, which was used to control for cage effects, samples were collected outside the cages. The cages where placed in blocks three and three, one for each the three treatments, on eight different locations in the experiment area. No significant difference was detected between the different treatments concerning diversity (Shannon diversity index: F3,25=1,39; P=0,27 and Simpson diversity index: F3,25=1,47; P=0,25), taxonomic richness (F3,25=1,74; P=0,19) nor density (F2,25=0.41; P=0,75) of the macroinvertebrate fauna. The lack of effect from predation of fish is most likely explained by the low water temperature during the experiment period. The lack of effect from waterfowl predation is most likely due to a low density of diving ducks, despite the season.

  • 228.
    Saarinen Claesson, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Survival of brown trout fry in nature: effects of activity, body size and starvation2014Independent thesis Advanced level (degree of Master (Two Years)), 40 poäng / 60 hpOppgave
    Abstract [en]

    The first year of life is one of the main survival bottlenecks for many fish species. Individual traits affecting survival can be morphological, physiological or behavioural. Body size, growth rate and activity have all been found to affect fitness in different organisms. However, the effects of these traits on fitness in natural conditions and for underyearlings are poorly investigated. In this study we attempted to induce compensatory growth in laboratory conditions in natural populations of brown trout fry (Salmo trutta). It was performed by exposing the fry to a period of restricted resources followed by a period of refeeding. Two behavioural trials were conducted on each individual where activity level was scored. All fish were subsequently released in their native stream and recaptured after a month to check for survival. We found that high individual activity level in an open field context increased the probability of survival under natural conditions. The importance of body size for survival decreased over time, and thus, with fish size. Full compensation was detected in body condition, while only partly compensation in weight and no compensation in length were detected during the experimental periods. Our results suggest that a brown trout fry’s individual activity level is repeatable and can be an important trait for selection in nature. The instable interactions between activity and life-history traits indicate environmental effects on these interactions. Furthermore, if body size is not the only trait affecting survival, compensation in body structures may not be a fast response to increase fitness after a period of growth depression.

  • 229.
    Sarin, Camilla
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Habitat utilisation of  burnet moths (Zygaena spp.) in southern Sweden: a multi-stage and multi-scale perspective2009Independent thesis Advanced level (degree of Master (Two Years)), 40 poäng / 60 hpOppgave
    Abstract [en]

    Three species of burnet moths (Zygaena filipendulae, Z. lonicerae and Z. viciae) were studied on the Baltic island Öland, Sweden, in order to reveal the habitat requirements of different life stages. Larvae were found among a higher cover of their most important host plant, Lotus corniculatus, Trifolium medium/pratense or Vicia spp., than were pupae or imagines, and were also observed on plants larger than randomly examined plants. Imagines actively selected nectar plants of Centaurea and Cirsium, growing in sunny conditions, but other red and violet Asteraceae flowers were also favoured. Pupae of Z. filipendulae appeared in taller vegetation than larvae and imagines, probably because the cocoons are spun high on stems of grasses and other plants. The chance of finding such suitable substrates rises with increasing vegetation height. A large scale analysis of occupancy patterns was also made, evaluating the relationship between burnet presence or absence and the area of meadows and pastures within 10 x 10 km grid cells in southern Sweden. All three species showed a positive relationship with increasing area of semi-natural grassland. Thresholds for the amount of habitat, below which the likelihood of occurrence declined more rapidly, could be distinguished around a 40-50 % probability of occurrence. Conservational work should aim at preserving and restoring open and sunny areas, rich in the respective host plants and nectar sources, but vegetation management must be executed with great care or late in the season to not harm unhatched pupae and to maintain substrates suitable for Z. filipendulae pupation.

  • 230.
    Scharis, Inger
    et al.
    Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Rasmussen, Gregory S. A.
    Painted Dog Conservation, Hwange National Park, PO Box 72, Dete, Zimbabwe.
    Laska, Matthias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Using morphometrics to quantitatively differentiateAfrican wild dog footprints from domestic dogfootprints – a pilot study2016Inngår i: African Journal of Ecology, ISSN 0141-6707, E-ISSN 1365-2028, Vol. 54, nr 1Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Reliable population estimation and species inventories areimportant for wildlife conservation, but such estimationsare often difficult due to unreliable identification of thespecies in question. Furthermore, for predator conflictresolution, it is essential to be able to reliably identify thepredator. This study presents a new method to quantitativelydistinguish African wild dog (Lycaon pictus) footprintsfrom feral domestic dog (Canis lupus familiaris)footprints. Footprint photographs were digitally processedusing Photoshop and the NIH image processing softwareImageJ, and total pad area and angles between thecentroids of the backpad and the digits of the paw weremeasured. Pad angles showed statistically significantdifferences between the two species and, with the exceptionthat there was no significant difference in pad areabetween African wild dog females and domestic dog males,total pad areas were also diagnostic. Consequently, thecombination of total pad area and the angle betweenbackpad and digits are useful discriminators to reliablyidentify the species from an unknown footprint.

  • 231.
    Sellman, Stefan
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Ecologically viable population sizes: Determining factors2010Independent thesis Advanced level (degree of Master (Two Years)), 40 poäng / 60 hpOppgave
    Abstract [en]

    The minimum ecologically viable population size (MEVP) of a species describes the minimum size at which the species itself or another species in the same ecosystem goes extinct as a result of the loss of inter-specific interactions. The MEVP shows a good potential for use as a tool for exploring the mechanisms behind species extinctions, but presently only a small amount of research has been done that takes advantage of this. In this study the MEVP is used to investigate what properties of species can be used as good indicators of ecological importance. 100 large computer generated food webs were created with an assembly model and the reduction in density that was necessary to induce an extinction event in the web was subsequently determined for each species within the webs. This change in density was then correlated with 28 different properties, measured for each species. The results show that properties that measure how well connected a species is, as well as measures of the species role as a prey item in the web are the ones with the greatest potential to find species with high MEVP. Further, the results put emphasis on the importance of regarding the web as a whole when working with species extinctions, while also highlighting the usefulness of the MEVP concept.

  • 232.
    Sellman, Stefan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Quantifying Risk in Epidemiological and Ecological Contexts2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The rates of globalization and growth of the human population puts ever increasing pressure on the agricultural sector to intensify and grow more complex, and with this intensification comes an increased risk of outbreaks of infectious livestock diseases. At the same time, and for the same reasons, the detrimental effect that humans have on other species with which we share the environment has never been more apparent, as the current rates of species loss from ecological communities rival those of ancient mass extinction events. In order to find ways to lessen the effects of and eventually solve such problems we need ways to quantify the risks involved, something that can be difficult when for instance the sheer size or sensitivity of the systems makes practical experimentation unsuitable. For these situations mathematical models have become invaluable tools due to their flexibility and noninvasiveness. This thesis presents four works involving the quantification of risk in livestock epidemic and ecological contexts using mathematical models. Two of them deal with extinctions of species within model ecological communities, and how species interactions play a role in the identity of the lost species following perturbations to specific species (Papers I and II). The other two regard how the spatial layout of the underlying population of livestock premises affect the risk of foot and mouth disease outbreaks among farms in the USA, and how models of such outbreaks can be optimized to improve their usefulness (Papers III and IV).

    Ecological communities consist of species and the often intricate pattern of interactions between them. These interspecies connections can propagate effects caused by disturbances in one end of the network, through the community via the links, to other parts of the network. In some cases, a reduction in the abundance of one species can cause the extinction of a second species before the first species disappears, something called functional extinction. Despite this, many conservation efforts revolve around simply keeping populations of single species at a high enough level for their own survival. In a model setting, the study of Paper I explores and attempts to quantify how common such functional extinctions are in relation to the alternative outcome that a perturbed species itself becomes extinct. This is done by first constructing stable model food webs describing predator-prey interactions of up to 50 species, parameterized through allometric relationships between metabolic processes and body size. Then the smallest amount of extra mortality that can be applied to each and every species in the web before any species become extinct is determined. The study shows that in these model communities, more often than not (>80%) another species, rather than the species that is subjected to the additional mortality will be the one to become extinct first.

    The approach of Paper I is taken further in Paper II by applying the same methodology to ecological networks that include mixtures of both antagonistic (predator-prey) and mutualistic (e.g. pollination and seed dispersal) interactions. The results further reinforce the findings of Paper I, and show that ecological networks containing a mixture of antagonistic and mutualistic interactions are more sensitive to functional extinctions than purely antagonistic or purely mutualistic ones, an important finding considering the diversity of interaction types in natural systems. Furthermore, the type of species found to have the lowest threshold before becoming functionally extinct were those with a mixture of interaction types, such as pollinating insects. Both Paper I and II consolidate the notion that when doing conservation work it is important to have the entire community in mind by considering the population sizes that are viable from a multi-species perspective, rather than just focusing on the minimum population sizes that are viable for the individual species.

    In Papers III and IV the focus changes somewhat, from models of ecological systems to models of how infectious livestock disease spread between farms in spatially explicit contexts. For this kind of model, information about the spatial distribution of the hosts is of course crucial, but not always readily available. In the USA, the only available information about livestock premises demography is aggregated at the county scale, meaning that the spatial distribution of the premises within each county is unknown. However, a method exists to simulate realistic stochastic spatial configurations of premises using a set of predictor variables, such as topology, climate and roads. An alternative approach that have been used previously is to assume a uniformly random spatial distribution of premises within each county. But to what extent does the choice between these two methods affect the model’s evaluation of the risk of disease outbreaks? In Paper III, this is analyzed specifically for foot and mouth disease. Through simulated outbreaks and by looking at the reproductive ratio of the disease, the outbreak dynamics within the two different spatial configurations of premises are compared. The results show that there is a clear difference in the risk of outbreaks between them, with the non-uniform distributions showing a general pattern of higher outbreak risk. However this difference is dependent on the size and geographic location of the county that the outbreak start in with larger counties in the west of the US showing a stronger effect.

    When running numerical simulations with large scale models such as the one used in Paper III, a considerable amount of replication is usually necessary in order to account for the high degree of stochasticity inherent to the problem. Even further replication is required when performing sensitivity analyses of model parameters or when exploring different scenarios, for instance when trying to determine the optimal control strategy for a disease. For this reason, the amount and quality of results that can be produced by such studies can quickly become limited by the availability of computational resources. Finding ways to optimize the computations involved with regard to simulation time is therefore of great value as it can be directly related to the robustness of the results. In Paper IV, an efficient optimization method for the kind of kernel-based local disease spread model used in paper III is presented. The method revolves around constructing a grid structure that is overlaid on top of the farm landscape and dividing the infection process into two steps, first evaluating if any farms within one of the grid squares can become infected given an over-estimation of the probability of infection, and then only if so, evaluate actual infection of a subset of the farms within the receiving square. The method is compared to similar published methods and is shown to be more efficient in most cases, while also being easy to implement and understand. Furthermore, while other methods often involve approximations of the transmission process in order to improve computational speed, the method of Paper IV is shown to be exact. This is a major advantage, since with an approximative method the extent to which the results are affected by the simplification is unknown unless the effect of the approximation is explicitly quantified. In most cases, such quantification would require extensive simulations with the unsimplified approach, something which of course may not be feasible.

    Delarbeid
    1. High frequency of functional extinctions in ecological networks
    Åpne denne publikasjonen i ny fane eller vindu >>High frequency of functional extinctions in ecological networks
    2013 (engelsk)Inngår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 499, nr 7459, s. 468-+Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Intensified exploitation of natural populations and habitats has led to increased mortality rates and decreased abundances of many species(1,2). There is a growing concern that this might cause critical abundance thresholds of species to be crossed(1,3-5), with extinction cascades and state shifts in ecosystems as a consequence(4,6,7). When increased mortality rate and decreased abundance of a given species lead to extinction of other species, this species can be characterized as functionally extinct even though it still exists. Although such functional extinctions have been observed in some ecosystems(3,4,8), their frequency is largely unknown. Here we use a new modelling approach to explore the frequency and pattern of functional extinctions in ecological networks. Specifically, we analytically derive critical abundance thresholds of species by increasing their mortality rates until an extinction occurs in the network. Applying this approach on natural and theoretical food webs, we show that the species most likely to go extinct first is not the one whose mortality rate is increased but instead another species. Indeed, up to 80% of all first extinctions are of another species, suggesting that a species ecological functionality is often lost before its own existence is threatened. Furthermore, we find that large-bodied species at the top of the food chains can only be exposed to small increases in mortality rate and small decreases in abundance before going functionally extinct compared to small-bodied species lower in the food chains. These results illustrate the potential importance of functional extinctions in ecological networks and lend strong support to arguments advocating a more community-oriented approach in conservation biology, with target levels for populations based on ecological functionality rather than on mere persistence(8-11).

    sted, utgiver, år, opplag, sider
    Nature Publishing Group, 2013
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-96709 (URN)10.1038/nature12277 (DOI)000322157900038 ()
    Merknad

    Funding Agencies|Linkoping University||

    Tilgjengelig fra: 2013-08-23 Laget: 2013-08-23 Sist oppdatert: 2018-02-18
    2. Pattern of functional extinctions in ecological networks with a variety of interaction types
    Åpne denne publikasjonen i ny fane eller vindu >>Pattern of functional extinctions in ecological networks with a variety of interaction types
    2016 (engelsk)Inngår i: Theoretical Ecology, ISSN 1874-1738, E-ISSN 1874-1746, Vol. 9, nr 1, s. 83-94Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    There is a strong trend of declining populations in many species of both animals and plants. Dwindling numbers of species can eventually lead to their functional extinction. Functional, or ecological, extinction occurs when a species becomes too rare to fulfill its ecological, interactive role in the ecosystem, leading to true (numerical) extinction of other depending species. Recent theoretical work on food webs suggests that the frequency of functional extinction might be surprisingly high. However, little is known about the risk of functional species extinctions in networks with other types of interactions than trophic ones. Here, we explore the frequency of functional extinctions in model ecological networks having different proportions of antagonistic and mutualistic links. Furthermore, we investigate the topological relationship between functionally and numerically extinct species. We find that (1) the frequency of functional extinctions is higher in networks containing a mixture of antagonistic and mutualistic interactions than in networks with only one type of interaction, (2) increased mortality rate of species having both mutualistic and antagonistic links is more likely to lead to extinction of another species than to extinction of the species itself compared to species having only mutualistic or antagonistic links, and (3) trophic distance (shortest path) between functionally and numerically extinct species is, on average, longer than one, indicating the importance of indirect effects. These results generalize the findings of an earlier study on food webs, demonstrating the potential importance of functional extinction in a variety of ecological network types.

    sted, utgiver, år, opplag, sider
    Springer Netherlands, 2016
    Emneord
    Functional extinction, Declining populations, Interaction type, Interaction strength, Ecological network
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-121570 (URN)10.1007/s12080-015-0275-7 (DOI)000373308600009 ()
    Merknad

    Funding agencies: Linkoping University

    Tilgjengelig fra: 2015-09-25 Laget: 2015-09-25 Sist oppdatert: 2018-02-18bibliografisk kontrollert
  • 233.
    Sellman, Stefan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Säterberg, Torbjörn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Ebenman, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Pattern of functional extinctions in ecological networks with a variety of interaction types2016Inngår i: Theoretical Ecology, ISSN 1874-1738, E-ISSN 1874-1746, Vol. 9, nr 1, s. 83-94Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is a strong trend of declining populations in many species of both animals and plants. Dwindling numbers of species can eventually lead to their functional extinction. Functional, or ecological, extinction occurs when a species becomes too rare to fulfill its ecological, interactive role in the ecosystem, leading to true (numerical) extinction of other depending species. Recent theoretical work on food webs suggests that the frequency of functional extinction might be surprisingly high. However, little is known about the risk of functional species extinctions in networks with other types of interactions than trophic ones. Here, we explore the frequency of functional extinctions in model ecological networks having different proportions of antagonistic and mutualistic links. Furthermore, we investigate the topological relationship between functionally and numerically extinct species. We find that (1) the frequency of functional extinctions is higher in networks containing a mixture of antagonistic and mutualistic interactions than in networks with only one type of interaction, (2) increased mortality rate of species having both mutualistic and antagonistic links is more likely to lead to extinction of another species than to extinction of the species itself compared to species having only mutualistic or antagonistic links, and (3) trophic distance (shortest path) between functionally and numerically extinct species is, on average, longer than one, indicating the importance of indirect effects. These results generalize the findings of an earlier study on food webs, demonstrating the potential importance of functional extinction in a variety of ecological network types.

  • 234.
    Senior, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Catchment factors affecting particle and phosphorus retention in constructed wetlands receiving agricultural runoff2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Eight agricultural catchments in south Sweden were investigated for factors that may affect phosphorus (P) load and retention in the downstream situated wetlands (WL). P load is known to affect retention, and is determined by hydrological and geographical catchment characteristics. The wetlands were small (0.02-0.88%) in relation to their catchments (CA) and varied in design. Net sedimentation and P retention was determined with sedimentation plates during one year. The variables that best explained differences in particles and TP retention were the hydraulic load (q), TP load and the wetland length to width ratio. Contrary to expectations there was no correlation between factors that could be associated with erosion (i.e. slope and soil clay content) and retention of neither particles nor TP. Generally, the highest amounts of settled particles and P were found close to the wetland inlets, but soil disturbance (i.e. tillage) and high q increased the settling distance. It was likely that the smallest clay particles were too unaggregated to settle within these wetlands. Factors not included, such as wetland vegetation and bioturbation may have a large impact on P retention and this should be further investigated. The study also points to the difficulties in scaling down geological and P loss data from a regional to a local scale, as there can be large local deviations from the regional standard values. An easy method for identification of local “hotspots” for P losses should be of value for planning the location of future wetlands.

  • 235.
    Sentis, Arnaud
    et al.
    University of South Bohemia, Czech Republic; Biol Centre AS CR, Czech Republic; University of Toulouse III, France.
    Binzer, Amrei
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten. Max Planck Institute Evolutionary Biol, Germany.
    Boukal, David S.
    University of South Bohemia, Czech Republic; Biol Centre AS CR, Czech Republic.
    Temperature-size responses alter food chain persistence across environmental gradients2017Inngår i: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 20, nr 7, s. 852-862Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Body-size reduction is a ubiquitous response to global warming alongside changes in species phenology and distributions. However, ecological consequences of temperature-size (TS) responses for community persistence under environmental change remain largely unexplored. Here, we investigated the interactive effects of warming, enrichment, community size structure and TS responses on a three-species food chain using a temperature-dependent model with empirical parameterisation. We found that TS responses often increase community persistence, mainly by modifying consumer-resource size ratios and thereby altering interaction strengths and energetic efficiencies. However, the sign and magnitude of these effects vary with warming and enrichment levels, TS responses of constituent species, and community size structure. We predict that the consequences of TS responses are stronger in aquatic than in terrestrial ecosystems, especially when species show different TS responses. We conclude that considering the links between phenotypic plasticity, environmental drivers and species interactions is crucial to better predict global change impacts on ecosystem diversity and stability.

  • 236.
    Shahin, Lara
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle.
    Analysis of some Chlorinated Pesticides in Jordanian Ground- and Surface Waters by Solid-Phase Extraction and Mass Spectrometric Detection- A Method development2004Independent thesis Advanced level (degree of Magister)Oppgave
    Abstract [en]

    A solid-phase extraction (SPE) method was developed for the determination of organochlorine pesticides, namely aldrin, alpha-BHC, beta-BHC, delta-BHC, dieldrin, endosulfan I, endosulfan II, endosulfan sulfate, endrin, endrin aldehyde, lindane, heptachlor, heptachlor epoxide, 4,4’-DDD, 4,4’-DDE and 4,4’- DDT in water. The effect of extraction conditions, such as the addition of sodium chloride and methanol to the sample prior to loading was studied. The sample was concentrated by a plain polystyrene-divinylbenzene resin, and the extract was eluted by ethyl acetate. Qualification and quantification of the target pesticides were performedby gas chromatography/ mass spectrometry (GC/MS) in the full-scan and selected ion-monitoring mode, respectively, and for better detection of pesticides in field samples the mass spectrometer was altered from electron ionization (EI) to chemical ionization mode (CI). The repeatability of the method for MilliQ-water fortified with pesticides at a level of 0.1 to 0.6 µg/l ranged from 8 to 18%, and the obtained recoveries ranged from 67 to 135%.

    The method was evaluated for the determination of organochlorine pesticides in fourteen surface- and groundwater samples taken from locations along King Talal Dam, King Abdullah Canal and Zarqa River in the Jordan Valley. The limit of detection of the pesticides residues in 500-ml field water samples ranged from 0.0009 to 15.7 ng/l. The obtained results confirmed the presence of trace amounts of some organochlorine pesticides in the analyzed samples, i.e. lindane and endosulfan compounds.

  • 237.
    Shilla, Dativa
    et al.
    Dar es Salaam University, Tanzania.
    Routh, Joyanto
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Using biochemical and isotopic tracers to characterise organic matter sources and their incorporation into estuarine food webs (Rufiji delta, Tanzania)2017Inngår i: Chemistry in ecology, ISSN 0275-7540, E-ISSN 1029-0370, Vol. 33, nr 10, s. 893-917Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fatty acid biomarkers and stable isotope signatures were used to identify the sources of particulate and sedimentary organic matter and its input into the food web through the dominant consumer within the mangrove-dominated Rufiji estuary, Tanzania. Specific fatty acids were used to identify the preferred basal sources of dominant fauna (i.e. filter feeder bivalves, snails, crabs, shrimps, and three fish species), and their presence in the water and sediment samples in the estuary. Both fatty acid and stable isotope results revealed that food web in the Rufiji estuary depended on a variety of carbon sources (mangroves, allochthonous terrestrial inputs, macroalgae, and phytoplankton), contributing to a different degree into the diets of primary consumers and members of near-shore fish, but none of them were obligatory for the survival of these species. The delta N-15 values of major primary producers and consumers/predators revealed a trend for delta N-15 enrichment with increasing trophic level. The ratio of docosahexaenoic acid to eicosapentaenoic acid (DHA:EPA) decreased from pelagic to benthic feeding fish. This indicated that fish with different feeding modes derived their fatty acids from different primary sources of nutrition, and suggested that the DHA: EPA ratio may be a useful indicator of feeding mode.

  • 238.
    Signori, Camila N.
    et al.
    Univ Sao Paulo, Brazil.
    Pellizari, Vivian H.
    Univ Sao Paulo, Brazil.
    Enrich Prast, Alex
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten. Univ Fed Rio De Janeiro UFRJ, Brazil.
    Sievert, Stefan M.
    WHOI, MA 02543 USA.
    Spatiotemporal dynamics of marine bacterial and archaeal communities in surface waters off the northern Antarctic Peninsula2018Inngår i: Deep-sea research. Part II, Topical studies in oceanography, ISSN 0967-0645, E-ISSN 1879-0100, Vol. 149, s. 150-160Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Seasonal changes in taxonomic and functional diversity of microbial communities in polar regions are commonly observed, requiring strategies of microbes to adapt to the corresponding changes in environmental conditions. These natural fluctuations form the backdrop for changes induced by anthropogenic impacts. The main goal of this study was to assess the seasonal and temporal changes in bacterial and archaeal diversity and community structure off the northern Antarctic Peninsula over several seasons (spring, summer, autumn) from 2013 to 2015. Ten monitoring stations were selected across the Gerlache and Bransfield Straits and nearby Elephant Island, and archaeal and bacterial communities examined by amplicon sequencing of 16S rRNA genes. Alpha-diversity indices were higher in spring and correlated significantly with temperature. Spring was characterized by the presence of SAR11, and microbial communities remaining from winter, including representatives of Thaumarchaeota (Nimosopurnilus), Euryarchaeota, members of Oceanospirillales, SAR324. Summer and autumn were characterized by a high prevalence of Flavobacteria (NS5 marine group and Polaribacter), Alphaproizobacteria (Rhodobacterales and SAR11 Glade) and Gammaproteobacteria (Oceanospirillales/Balneatrix and Celivibrionales), generally known to be associated with organic matter degradation. Relatively higher abundance of phytoplankton groups occurred in spring, mainly characterized by the presence of the haptophyte Phaeocystis and the diatom Corethron, influencing the succession of heterotrophic bacterial communities. Microbial diversity and community structure varied significantly over time, but not over space, i.e., were similar between monitoring stations for the same time. In addition, the observed interannual variability in microbial community structure might be related to an increase in sea surface temperature. Environmental conditions related to seasonal variation, including temperature and most likely phytoplankton derived organic matter, appear to have triggered the observed shifts in microbial communities in the waters off the northern Antarctic Peninsula.

    Fulltekst tilgjengelig fra 2019-12-20 00:01
  • 239.
    Simmons, Benno I.
    et al.
    Univ Cambridge, England.
    Cirtwill, Alyssa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Baker, Nick J.
    Univ Canterbury, New Zealand.
    Wauchope, Hannah S.
    Univ Cambridge, England.
    Dicks, Lynn V.
    Univ East Anglia, England.
    Stouffer, Daniel B.
    Univ Canterbury, New Zealand.
    Sutherland, William J.
    Univ Cambridge, England.
    Motifs in bipartite ecological networks: uncovering indirect interactions2019Inngår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 128, nr 2, s. 154-170Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Indirect interactions play an essential role in governing population, community and coevolutionary dynamics across a diverse range of ecological communities. Such communities are widely represented as bipartite networks: graphs depicting interactions between two groups of species, such as plants and pollinators or hosts and parasites. For over thirty years, studies have used indices, such as connectance and species degree, to characterise the structure of these networks and the roles of their constituent species. However, compressing a complex network into a single metric necessarily discards large amounts of information about indirect interactions. Given the large literature demonstrating the importance and ubiquity of indirect effects, many studies of network structure are likely missing a substantial piece of the ecological puzzle. Here we use the emerging concept of bipartite motifs to outline a new framework for bipartite networks that incorporates indirect interactions. While this framework is a significant departure from the current way of thinking about bipartite ecological networks, we show that this shift is supported by analyses of simulated and empirical data. We use simulations to show how consideration of indirect interactions can highlight differences missed by the current index paradigm that may be ecologically important. We extend this finding to empirical plant-pollinator communities, showing how two bee species, with similar direct interactions, differ in how specialised their competitors are. These examples underscore the need to not rely solely on network- and species-level indices for characterising the structure of bipartite ecological networks.

  • 240.
    Sjöberg, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    The Effect of Extra Food Stimulation on Asian Elephants (Elephas maximus) Kept at Kolmården Zoo2011Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Stereotypic behaviors in all animals are more often than not associated with poor welfare. Limited access to perform species specific behaviors is often a reason for the development of stereotypies. Elephants with their great intelligence and need of social contact, coupled with a destructive a behavior are especially difficult to house in captivity. To decrease the occurrence of stereotypic behaviors in elephants, environmental enrichment in form of food enrichment is a good option, since elephants have a great need of foraging. The aim of this study was to investigate if an extra supply of food enrichment could decrease the presence of stereotypic behaviors at night in three Asian elephants at Kolmården zoo. Already existing hay nets attached to wires in the roof were used and connected to a timer. The hay nets were lowered to vision trunk reach between 6:00 am and 6:30 am during five days and the frequencies of selected behaviors were compared with the frequencies of the same behaviors during five preceding baseline nights. The animals were filmed using mounted cameras with IR lights. There was a significant decrease of stereotypic behavior for one of the elephants, but all three showed an increase in foraging whereof the increases were significant for two of them. One of the elephants showed no stereotypic behaviors at all during the study. To keep in mind is that the elephants have different backgrounds and experiences which might have influenced the results.

  • 241.
    Sonelin, Sarah
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Effekter av luftföroreningar på lavar och grönalger på lind i Norrköpings kommun2012Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [sv]

    Syftet med denna studie var att undersöka vilka effekter luftföroreringar har på lavar och grönalger som växer på lindar, genom att jämföra lavfloran i urban miljö och i landsbygdsmiljö. Mer specifikt var syftet att utreda hur avstånd till närmaste väg, trafikintensitet och trädets exponerade respektive icke-exponerade sida gentemot en väg påverkar lavfloran i urban miljö. 18 utvalda lavarter samt grönalger eftersöktes på 86 lindar i urban miljö och 37 i landsbygdsmiljö inom Norrköpings kommun. Resultaten visade att artantalet, samt förekomsten och täckningsgraden för flertalet lavar var större i landsbygdsmiljö jämfört med urban miljö. Kortare avstånd till närmaste väg och hög trafikintensitet hade negativ effekt på flertalet lavar. I båda fallen visades det motsatta för grönalger. Det fanns ingen skillnad i förekomster av lavar om de exponerades utåt mot vägen eller bort från vägen.

  • 242.
    Strano, Cinzia P.
    et al.
    University of Mediterranea Reggio Calabria, Italy.
    Malacrinò, Antonino
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten. University of Mediterranea Reggio Calabria, Italy.
    Campolo, Orlando
    University of Mediterranea Reggio Calabria, Italy.
    Palmeri, Vincenzo
    University of Mediterranea Reggio Calabria, Italy.
    Influence of Host Plant on Thaumetopoea pityocampa Gut Bacterial Community2018Inngår i: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 75, nr 2, s. 487-494Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Microbial communities associated to the gut of insects are attracting an increasing interest, mainly because of their role in influencing several host life-traits. The characterization of the gut microbial community is pivotal for understanding insect ecology and, thus, to develop novel pest management strategies. The pine processionary moth, Thaumetopoea pytiocampa (Denis amp; Schiff.) (Lepidoptera: Thaumetopoeidae), is a severe defoliator of pine forests, able to feed on several pine species. In this work, we performed a metabarcoding analysis to investigate, for the first time, the diversity of the gut bacterial community of pine processionary larvae associated with three different host pine species (Pinus halepensis, Pinus nigra subsp. laricio, and Pinus pinaster). We found that the gut microbial community of T. pityocampa larvae collected on P. halapensis was different from that associated with larvae collected from P. nigra and P. pinaster. Moreover, the high presence of bacteria belonging to the genera Modestobacter, Delftia, and unidentified Methylobacteriaceae retrieved in larvae feeding on P. halapensis suggested that specific interactions can occur. Our results provide the evidence that different host plant differently impact on the microbiota diversity of T. pityocampa larvae, contributing to the general knowledge of this pest with information that could be useful in shaping the next generation of pest control strategies.

  • 243.
    Sundin, Fia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Occurrence of insects in relation to short term forest fire history2014Independent thesis Advanced level (degree of Master (Two Years)), 40 poäng / 60 hpOppgave
    Abstract [en]

    Several boreal insect species are pyrophilic and are more or less dependent on recently burned forest. Many pyrophilic species are attracted to potential substratum-rich recently burned forest by smoke and heat. Modern forestry has dramatically reduced the amount and size of forest fires in northern Europe during the last century and as a result several of the pyrophilic species are now threatened. The aim of this study was to analyse how the occurrence of insects such as Diptera of the pyrophilic genus Microsania, pyrophilic Coleoptera, obligate saproxylic Coleoptera and Coleoptera with unknown fire-dependency were affected by the forest fire history during the last 14 years. The aim was also to analyse what effect the spatial and temporal scales of the forest fire history has on the occurrence of these insects. This was done using smoke attraction traps, a unique method for catching pyrophilic insects without an actual forest fire, and analysing the results with a unique regional short term forest fire history dataset, containing all fires between the years of 1998-2011 in Östergötland county in Sweden. The forest fires were clustered and more abundant in the eastern parts of the county. Seven out of eleven pyrophilic beetles were positively correlated with recent forest fires, mostly for the smaller spatial scales, 100 m – 5000 m. The abundance of many beetles with unknown fire-dependency were associated with recent forest fires. The general ecology for many of these species is not well known but some of these beetles might be favoured by different substrates that are created by fires. Strategically placed conservation burns can help to increase the spatial and temporal connectivity of forest fires to conserve both fire dependent and generally associated insects in the future.

  • 244.
    Sundman, Ann-Sofie
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Personality in piglets: Is there a difference in personality traits between pigs from different teat order positions?2011Independent thesis Basic level (degree of Bachelor), 15 poäng / 22,5 hpOppgave
    Abstract [en]

    The objective of this study was to determine whether piglets from different positions in the teat order differ inpersonality. Teat order is established within the first days after birth and from that time, piglets basically suckle fromthe same teat pair until weaning. Three piglets from each of 21 litters (n = 63) were chosen for their place in teatorder; one from anterior teats (A), one from middle teats (B), and one from rear teats (C). The piglets were observedduring suckling, undisturbed behaviour, a novel object test and a straw test. A total of 13 behaviours were registered.A significant difference (P < 0.05) between A, B and C piglets was found in the frequency of disputes duringsuckling, where B piglets were most involved in disputes and C piglets least involved, and a tendency (P < 0.1) wasfound in frequency of undisturbed playing and exploration. A piglets played and explored most, and C piglets least.Four interesting components were found with principal component analysis, explaining 62.4 % of the total variation.These represent personality traits tentatively named exploration, playfulness, food interest and straw interest. Therewere no significant differences in personality type between A, B and C piglets although a tendency that A pigletswere most playful and C piglets were least playful was found. Hence, this study suggests that there might be acorrelation between teat order position and personality.

  • 245.
    Svalberg, Andrea
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Estimating Detection Probability and Abundance for the Black Caiman (Melanosuchus niger) and the Yacare Caiman (Caiman yacare)2016Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    The black caiman (Melanosuchus niger) and the yacare caiman (Caiman yacare) have in the past been exposed to overexploitation due to the economic profit for their hides, and therefore suffered from great declines in population sizes, especially black caimans. Legal regulation efforts made it possible for these two species to recover and today they are widely distributed in South America. Evaluation of protection and management of populations of top predators like these caimans depend on the ability to detect the animals. The probability of detecting a crocodile, or any animal, is affected by several factors such as habitat complexity and behaviour why it is of importance to acknowledge such matter in order to obtain reliable results for further implications. This study aims to investigate the detection probability and abundances in these two species as a contribution to the monitoring efforts at a local scale. Night counts were performed in Cedral lagoon located in the Beni region in Bolivia. By using the relation between marked animals and resightings of them, as well as the abundance estimate produced by the Lincoln-Petersen estimator, estimates of detection probabilities could be accounted for the total caiman population (black plus yacare caimans) and the black caiman population. Very low sighting probabilities (p = 0.03) were obtained when based on marked animals who tend to be more wary after a capture event. Those based on the L-P output were higher (total caiman population p = 0.15, black caimans p = 0.15). Population sizes were estimated to 25 ± 8.5 black caimans and 34 ± 12 caimans in total. The population size based on marked animals was 12 ± 25.4 caimans.

  • 246.
    Svennar, Erica
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ekologi. Linköpings universitet.
    Metoder för att undersöka effekterna av naturvårdshänsynen i skogsbruket efter den nya skogsvårdslagen2010Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    In 1994 a new Forestry Act was accepted in Sweden. One of its aims was to raise the consideration for preservation of biodiversity. Since this happened over 15 years ago there is now an interest in analyzing if the law has been effective in its purpose. In this study methods suitable for analysis are being investigated. The study contents a pilot study of methods for five parameters that can validate if the law has been followed. The fieldstudy were executed in Orsa, Dalarna, Sweden in a managed forest and where last clearcut was done after 1994. The work consisted of measuring the parameters in the field and to compare them with data from before 1994. The benefits of the parameters and the current and previous Forestry Act and their differences are discussed in the report. The parameters examined were the distribution of tree species, standing dead wood, smaller areas saved for preservation, big trees and trees with cavities/cavernous trees. All of these plus a few other variables favourable for the diversity of species in the forest are dealt with in the 30 § in the Forestry Act of 1994. The study implied that the variables reported to be favourable for biodiversity, and possible to investigate within the restrictions of this study, seemed to have increased. The results should however be interpreted with care since the study is small and the reference values sometimes were missing or covering larger areas than the field data.

  • 247.
    Svensson, Teresia
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Measurements and fluxes of volatile chlorinated organic compounds (VOCl) from natural terrestrial sources: Measurement techniques and spatio-temporal variability of flux estimates2019Rapport (Annet vitenskapelig)
    Abstract [no]

    Flyktiga organiska föreningar (VOC) och i synnerhet klorerade VOCs (VOCls) betraktas som miljö­farliga ämnen i vattenmiljöer på grund av sina toxiska egenskaper, men även i atmosfären eftersom de har en stor inverkan på atmosfärskemin, t ex genom att påverka ozonskiktet. Ett antal studier har hittat flera naturliga källor för VOCl och därmed förändrat synen på VOCls som endast producerade av människor. Trots det så saknas kunskaperna fortfarande om utsläpp de naturliga flödena av VOCls, särskilt när det gäller variation i tid och rum från terrestra miljöer. I kärnkraftsindustrin är Cl­36 en dosdominerande radionuklid för en del avfallströmmar. Därför behövs en bättre förståelse för omsättningen av klor i ytnära ekosystem.

    Klormetan är den mest studerade av VOCl och den näst mest studerade är kloroform. Några andra studier har uppskattat flöde av andra VOCl som tetraklormetan (CCl4), metylkloroform (CH3CCl3), tetrakloretan (C2H2Cl4), freoner (CFC), kloretan (C2H5Cl), bromodiklormetan (CHBrCl2). Studier genomfördes i klimat och markbaserade ekosystem som sträcker sig från arktisk tundra till tropisk regnskog, men de flesta studier fokuserar på tempererat klimatområde. Våtmarker och kustsystem är de studerande dominerande ekosystemen. Kammare är den vanligaste metoden för att uppskatta flöden av av VOCls, men det finns också några studier med koncentrationsgradienter i markprofiler, och en form av mikrometeorologimetodik. De metodologiska osäkerheterna som diskuteras kretsar i första hand kring kontamination, få replikat, design av fältmätningar och fältmätningarnas påverkan på markprocesser och därmed indirekt på flödena. Trots de många utmaningarna för att mäta VOCls och uppskatta flödena är det klart att flödet av klor till atmosfären är ett viktigt flöde i klors biogeo­kemiska cykel i terrestra ekosystem. Skogsekosystem kan avge så mycket som 0.1 g m–2, vilket är 40 % av våtdepositionen av klorid och det finns studier som tyder på att våtmarker är en långt mycket större källa till klor i atmosfären än man tidigare trott.

  • 248.
    Säterberg, Torbjörn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Functional Extinctions of Species in Ecological Networks2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Current rates of extinctions are estimated to be around 1000 times higher than background rates that would occur without anthropogenic impacts. These extinction rates refer to the traditional view of extinctions, i.e. numerical extinctions. This thesis is about another type of extinctions: functional extinctions. Those occur when the abundance of a species is too small to uphold the species’ ecologically interactive role. I have taken a theoretical approach and used dynamical models to investigate functional extinctions and threshold values for species’ mortality rates in ecological networks. More specifically, I have derived threshold values for focal species mortality rates at which another species or the focal species itself goes numerically extinct (Paper I-II), or transgresses some predefined threshold abundance (Paper III). If an increased mortality rate of a focal species causes another species to go numerically extinct, the focal species can be regarded as functionally extinct, since its abundance is no longer large enough to uphold its ecologically interactive role. Such functional extinctions are investigated in the first papers (Paper I-II). In the following paper, limits for both increased and decreased mortality rates of species are explored (Paper III). Paper III also extends the basic theoretical idea developed in paper I-II into a more applied setting. In this paper I develop a time series approach aimed at estimating fishing mortalities associated with a low risk that any species in a community transgresses some predefined critical abundance threshold. In the last paper (Paper IV) the community wide effect of changes in the abundance of species is investigated.

    In the first paper (Paper I) I investigate threshold levels for the mortality rate of species in ecological networks. When an increased mortality rate of a focal species causes another species to go extinct, the focal species can be characterized as functional extinct, even though it still exists. Such functional extinctions have been observed in a few systems, but their frequency and general patterns have been unexplored. Using a new analytical method the patterns and frequency of functional extinctions in theoretical and empirical ecological networks are explored. It is found that the species most likely to be the first to go extinct is not the species whose mortality rate is increased, but instead another species in the network. The species which goes extinct is often not even directly linked to the species whose mortality rate is increased, but instead indirectly linked. Further, it is found that large-bodied species at the top of food chains can only be exposed to small increases in mortality rate and small decreases in abundance before going functionally extinct compared to small-bodied species lower in the food chains. These results illustrate the potential importance of functional extinctions in ecological networks and lend support to arguments advocating a more community-oriented approach in conservation biology, with target levels for populations based on ecological functionality rather than the mere persistence of species.

    In Paper II I use the approach developed in Paper I to explore the frequency and patterns of functional extinctions in ecological networks with varying proportions of mutualistic and antagonistic (predator-prey) interactions. The general results from Paper I are also found in Paper II; that is, an increased mortality rate of one focal species often first leads to an extinction of another species rather than to an extinction of the focal species itself.

    Further, the frequency of functional extinctions is higher in networks containing a mixture of interaction types than in networks with only antagonistic interactions. Overall, this study generalize the findings of paper I for networks containing a variety of interaction types.

    To make the theoretical approaches developed in paper I-II operational in a management setting I develop a time series approach aimed at estimating ecologically sustainable fishing mortalities in a multispecies fisheries context (Paper III). An ecologically sustainable fishing mortality is here defined as a long-term fishing mortality associated with a multispecies objective which infers a low risk that any species, either the focal species itself or another species, in a community transgresses a critical biomass limit, below which the risk of recruitment failure is high. The approach is exemplified using a statistical food web model of the dominating fish stocks in the Baltic Sea. For the most abundant fish stock a counterintuitive result is found; it is more likely that the multispecies objective is met if its mortality caused by fishing is increased compared to if it is decreased. Further, simultaneous changes of the fishing mortality of a number of interacting species in the food web model shows a much narrower region of possible sustainable fishing mortalities than a single species approach, something that is not captured by current stock assessment models. Altogether these results are governed by indirect effects propagating in the community and pinpoints the need to adopt community dynamical approaches in fisheries management.

    The population sizes of many species in the world are declining. Negative population trends are particular pronounced in large-bodied herbivores and carnivores, species known to play important regulatory roles in many ecosystems. Although this indicates that the ecological consequence of declining populations of species might be profound, its impact on ecosystem stability remains largely unexplored. In paper IV it is therefore explored how declining populations of rare and common species affects the resilience – recovery rate – of ecological networks. An analytical approximation shows that network resilience is a function of the harmonic mean of the species’ abundances. This means that network resilience is especially sensitive to declining abundances of rare species. Consistent with this analytically derived result, a clear and positive relationship between resilience and the abundance of the rarest species in a broad spectrum of dynamical models of ecological networks is found. Together these results illustrate the potentially negative consequences of declining populations of rare species for the stability of the ecological systems in which they are embedded, and provide ecological arguments for the protection and management of rare species.

    Delarbeid
    1. High frequency of functional extinctions in ecological networks
    Åpne denne publikasjonen i ny fane eller vindu >>High frequency of functional extinctions in ecological networks
    2013 (engelsk)Inngår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 499, nr 7459, s. 468-+Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Intensified exploitation of natural populations and habitats has led to increased mortality rates and decreased abundances of many species(1,2). There is a growing concern that this might cause critical abundance thresholds of species to be crossed(1,3-5), with extinction cascades and state shifts in ecosystems as a consequence(4,6,7). When increased mortality rate and decreased abundance of a given species lead to extinction of other species, this species can be characterized as functionally extinct even though it still exists. Although such functional extinctions have been observed in some ecosystems(3,4,8), their frequency is largely unknown. Here we use a new modelling approach to explore the frequency and pattern of functional extinctions in ecological networks. Specifically, we analytically derive critical abundance thresholds of species by increasing their mortality rates until an extinction occurs in the network. Applying this approach on natural and theoretical food webs, we show that the species most likely to go extinct first is not the one whose mortality rate is increased but instead another species. Indeed, up to 80% of all first extinctions are of another species, suggesting that a species ecological functionality is often lost before its own existence is threatened. Furthermore, we find that large-bodied species at the top of the food chains can only be exposed to small increases in mortality rate and small decreases in abundance before going functionally extinct compared to small-bodied species lower in the food chains. These results illustrate the potential importance of functional extinctions in ecological networks and lend strong support to arguments advocating a more community-oriented approach in conservation biology, with target levels for populations based on ecological functionality rather than on mere persistence(8-11).

    sted, utgiver, år, opplag, sider
    Nature Publishing Group, 2013
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-96709 (URN)10.1038/nature12277 (DOI)000322157900038 ()
    Merknad

    Funding Agencies|Linkoping University||

    Tilgjengelig fra: 2013-08-23 Laget: 2013-08-23 Sist oppdatert: 2018-02-18
    2. Pattern of functional extinctions in ecological networks with a variety of interaction types
    Åpne denne publikasjonen i ny fane eller vindu >>Pattern of functional extinctions in ecological networks with a variety of interaction types
    2016 (engelsk)Inngår i: Theoretical Ecology, ISSN 1874-1738, E-ISSN 1874-1746, Vol. 9, nr 1, s. 83-94Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    There is a strong trend of declining populations in many species of both animals and plants. Dwindling numbers of species can eventually lead to their functional extinction. Functional, or ecological, extinction occurs when a species becomes too rare to fulfill its ecological, interactive role in the ecosystem, leading to true (numerical) extinction of other depending species. Recent theoretical work on food webs suggests that the frequency of functional extinction might be surprisingly high. However, little is known about the risk of functional species extinctions in networks with other types of interactions than trophic ones. Here, we explore the frequency of functional extinctions in model ecological networks having different proportions of antagonistic and mutualistic links. Furthermore, we investigate the topological relationship between functionally and numerically extinct species. We find that (1) the frequency of functional extinctions is higher in networks containing a mixture of antagonistic and mutualistic interactions than in networks with only one type of interaction, (2) increased mortality rate of species having both mutualistic and antagonistic links is more likely to lead to extinction of another species than to extinction of the species itself compared to species having only mutualistic or antagonistic links, and (3) trophic distance (shortest path) between functionally and numerically extinct species is, on average, longer than one, indicating the importance of indirect effects. These results generalize the findings of an earlier study on food webs, demonstrating the potential importance of functional extinction in a variety of ecological network types.

    sted, utgiver, år, opplag, sider
    Springer Netherlands, 2016
    Emneord
    Functional extinction, Declining populations, Interaction type, Interaction strength, Ecological network
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-121570 (URN)10.1007/s12080-015-0275-7 (DOI)000373308600009 ()
    Merknad

    Funding agencies: Linkoping University

    Tilgjengelig fra: 2015-09-25 Laget: 2015-09-25 Sist oppdatert: 2018-02-18bibliografisk kontrollert
  • 249.
    Säterberg, Torbjörn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. Swedish Univ Agr Sci, Sweden.
    Casini, Michele
    Swedish Univ Agr Sci, Sweden.
    Gardmark, Anna
    Swedish Univ Agr Sci, Sweden.
    Ecologically Sustainable Exploitation Rates-A multispecies approach for fisheries management2019Inngår i: Fish and Fisheries, ISSN 1467-2960, E-ISSN 1467-2979Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fisheries management is slowly evolving from its traditional single-species focus to a more holistic ecosystem-based approach. Yet, limits for exploitation are almost always set based on single-species models, treating species as isolated entities. This is problematic since the sustainability of a fishery hinges on its effects on the exploited community as a whole. Here, we develop a novel analytical approach of estimating exploitation rates that are sustainable with respect to the state of whole fish communities. Our approach simultaneously addresses species interactions, environmental covariates and natural variability of population sizes, yet it is framed around a simple and accessible objective. We derive Ecologically Sustainable Exploitation Rates, that is exploitation rates associated with a maximum acceptable probability (determined by management) that any interacting species decreases to an unacceptably low population size. Using models fitted to an exploited fish community, we show how accounting for species interactions constrains the possibilities for ecologically sustainable exploitation. The conventional omission of species interactions may thus result in overestimated exploitation limits. Moreover, our application rendered a counterintuitive result: it suggests that the exploitation of one species should increase, as compared to mean historical levels, for the purpose of conservation of the community as a whole. Such insights could impossibly be gained using single-species approaches, illustrating the need to adopt multispecies models in fisheries management. Analytical derivation of Ecologically Sustainable Exploitation Rates offers a mean to do so.

  • 250.
    Säterberg, Torbjörn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. Swedish Univ Agr Sci, Sweden.
    Jonsson, Tomas
    Swedish Univ Agr Sci, Sweden; Skovde Univ, Sweden.
    Yearsley, Jon
    Univ Coll Dublin, Ireland; UCD Earth Inst, Ireland.
    Berg, Sofia
    Skovde Univ, Sweden.
    Ebenman, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten. Stockholm Univ, Sweden.
    A potential role for rare species in ecosystem dynamics2019Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, artikkel-id 11107Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ecological importance of common species for many ecosystem processes and functions is unquestionably due to their high a bundance.Yet, the importance of rare species is much less understood. Here we take a theoretical approach, exposing dynamical models of ecological networks to small perturbations, to explore the dynamical importance of rare and common species. We find that both species types contribute to the recovery of communities following generic perturbations (i.e. perturbations affecting all species).Yet, when perturbations are selective (i.e. affects only one species), perturbations to rare species have the most pronounced effect on community stability. We show that this is due to the strong indirect effects induced by perturbations to rare species. Because indirect effects typically set in at longer timescales, our results indicate that the importance of rare species may be easily overlooked and thus underrated. Hence, our study provides a potential ecological motive for the management and protection of rare species.

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