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  • 51.
    Cirtwill, Alyssa
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten. Stockholm Univ, Sweden.
    Eklöf, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Roslin, Tomas
    Swedish Univ Agr Sci, Sweden.
    Wootton, Kate
    Swedish Univ Agr Sci, Sweden.
    Gravel, Dominique
    Univ Sherbrooke, Canada.
    A quantitative framework for investigating the reliability of empirical network construction2019Inngår i: Methods in Ecology and Evolution, ISSN 2041-210X, E-ISSN 2041-210X, Vol. 10, nr 6, s. 902-911Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Descriptions of ecological networks typically assume that the same interspecific interactions occur each time a community is observed. This contrasts with the known stochasticity of ecological communities: community composition, species abundances and link structure all vary in space and time. Moreover, finite sampling generates variation in the set of interactions actually observed. For interactions that have not been observed, most datasets will not contain enough information for the ecologist to be confident that unobserved interactions truly did not occur. Here, we develop the conceptual and analytical tools needed to capture uncertainty in the estimation of pairwise interactions. To define the problem, we identify the different contributions to the uncertainty of an interaction. We then outline a framework to quantify the uncertainty around each interaction by combining data on observed co-occurrences with prior knowledge. We illustrate this framework using perhaps the most extensively sampled network to date. We found significant uncertainty in estimates for the probability of most pairwise interactions. This uncertainty can, however, be constrained with informative priors. This uncertainty scaled up to summary measures of network structure such as connectance and nestedness. Even with informative priors, we are likely to miss many interactions that may occur rarely or under different local conditions. Overall, we demonstrate the importance of acknowledging the uncertainty inherent in network studies, and the utility of treating interactions as probabilities in pinpointing areas where more study is needed. Most importantly, we stress that networks are best thought of as systems constructed from random variables, the stochastic nature of which must be acknowledged for an accurate representation. Doing so will fundamentally change network analyses and yield greater realism.

  • 52.
    Cirtwill, Alyssa
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten. University of Canterbury, New Zealand; University of Otago, New Zealand.
    Lagrue, Clement
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Poulin, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Stouffer, Daniel B.
    University of Canterbury, New Zealand.
    Host taxonomy constrains the properties of trophic transmission routes for parasites in lake food webs2017Inngår i: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 98, nr 9, s. 2401-2412Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Some parasites move from one host to another via trophic transmission, the consumption of the parasite (inside its current host) by its future host. Feeding links among free-living species can thus be understood as potential transmission routes for parasites. As these links have different dynamic and structural properties, they may also vary in their effectiveness as trophic transmission routes. That is, some links may be better than others in allowing parasites to complete their complex life cycles. However, not all links are accessible to parasites as most are restricted to a small number of host taxa. This restriction means that differences between links involving host and non-host taxa must be considered when assessing whether transmission routes for parasites have different food web properties than other links. Here we use four New Zealand lake food webs to test whether link properties (contribution of a link to the predators diet, prey abundance, prey biomass, amount of biomass transferred, centrality, and asymmetry) affect trophic transmission of parasites. Critically, we do this using both models that neglect the taxonomy of free-living species and models that explicitly include information about which free-living species are members of suitable host taxa. Although the best-fit model excluding taxonomic information suggested that transmission routes have different properties than other feeding links, when including taxonomy, the best-fit model included only an intercept. This means that the taxonomy of free-living species is a key determinant of parasite transmission routes and that food-web properties of transmission routes are constrained by the properties of host taxa. In particular, many intermediate hosts (prey) attain high biomasses and are involved in highly central links while links connecting intermediate to definitive (predator) hosts tend to be dynamically weak.

  • 53.
    Cirtwill, Alyssa
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Eklöf, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Feeding environment and other traits shape species roles in marine food webs2018Inngår i: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 21, nr 6, s. 875-884Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Food webs and meso-scale motifs allow us to understand the structure of ecological communities and define species roles within them. This species-level perspective on networks permits tests for relationships between species traits and their patterns of direct and indirect interactions. Such relationships could allow us to predict food-web structure based on more easily obtained trait information. Here, we calculated the roles of species (as vectors of motif position frequencies) in six well-resolved marine food webs and identified the motif positions associated with the greatest variation in species roles. We then tested whether the frequencies of these positions varied with species traits. Despite the coarse-grained traits we used, our approach identified several strong associations between traits and motifs. Feeding environment was a key trait in our models and may shape species roles by affecting encounter probabilities. Incorporating environment into future food-web models may improve predictions of an unknown network structure.

  • 54.
    Dahl, Kristoffer
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Management effects on butterfly and bumblebee abundance in Swedish semi-natural grasslands2015Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    The amount of semi-natural grasslands has decreased in the agricultural landscape and because of this many grassland species are declining. Semi-natural grasslands are dependent on management, but different studies suggest that different management methods are most favorable to species richness and abundance. The aim of this study was to compare the effects of mowing and grazing on butterfly and bumblebee abundance in Swedish semi-natural grasslands. We used data collected through the Swedish environmental monitoring program NILS. We identified 31 comparable meadows and chose 1-10 pastures in the area surrounding each meadow. For six different species groups we calculated the number of individuals found per 100 m. By standardizing the values of the difference between the means for meadows and pastures we were able to compare the effects of the two methods on abundance in each species group. No species group showed a preference for pastures. A significant preference for meadows was found for two butterfly species groups. The four other groups showed a trend to prefer meadows before pastures. According to our study the recommended management method should be mowing, considering protection of butterflies and bumblebees.

  • 55.
    Dahlerup, Nina
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Effects of site quality and surrounding landscape on bryophytes and brackets on logs in woodland key habitats2010Independent thesis Advanced level (degree of Master (One Year)), 30 poäng / 45 hpOppgave
    Abstract [en]

    A tool for management and conservation of valuable forests in Sweden are WKH:s. In this study WKH:s different in size, connectivity, amount of dead wood and quality of logs were investigated for species richness of bryophytes and brackets on coniferous logs. The aim was to clarify which scales and features that was important for the diversity of species as well as for individual species. The results showed that the amount of dead wood was most important on the site scale, and some species were affected at the landscape scale, a positive effect of valuable tracts. On the scale of individual logs, factors such as diameter, sun exposure, succession stage, contact with ground and ground bryophytes cover was most important. Red-listed species preferred logs with large diameter and late successional stages. The conclusion was that the quality of the substrate and the amount of dead wood was most important, but the amount of WKH:s on the landscape scale was also important for some species.

  • 56.
    Danielsson, Elsa
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Carlsson, Evelina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    En jämförande studie av skogsstrukturer i olika skogstyper i Östergötland: – och ett förslag på hur ett biologiprojekt som behandlar detta kan genomföras i gymnasiekursen Biologi 12017Independent thesis Advanced level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Syftet med denna studie är att undersöka vilka skillnader i skogsstrukturer det finns mellan olika skogstyper i Östergötland, samt att diskutera hur dessa skillnader kan påverka den biologiska mångfalden. De skogstyper vi besökt är; hyggen, skogar som är ungefär 40 år gamla, avverkningsanmälda skogar samt naturskogar som är bevarade som naturreservat. De skogsstrukturer vi undersökt är; trädarter, diameter på träd och död ved, nedbrytningsstadie på död ved, spår av brand samt antal håligheter i träd och död ved. Vår studie visade att alla skogstyper hade åtminstone någon av de strukturer som kännetecknar en skog med höga naturvärden och därmed högre biologisk mångfald. Naturreservat var den skogstyp som hade flest skogsstrukturer som kännetecknar skogar med höga naturvärden. Detta tyder på att de hade en större biologisk mångfald gentemot de andra skogstyperna. Hyggen var den skogstyp som uppvisade minst skogsstrukturer som kännetecknar skogar med höga naturvärden vilket tyder på att den biologiska mångfalden var minst på hyggen. Syftet med studien är även att utforma en skoluppgift som liknar vår studie men är anpassad till biologiundervisningen i gymnasieskolan. För att göra detta har vi valt att återskapa vårt arbete som ett biologiprojekt för gymnasiekursen Biologi 1. Detta biologiprojekt innefattar en exkursion med förberedelser och efterarbete.

  • 57.
    Dorozynska, Dorota
    Linköpings universitet.
    En studie av retentionen i floden Oder och dess avrinningsområden, Polen.2004Independent thesis Advanced level (degree of Magister)Oppgave
    Abstract [en]

    Nutrient enrichment is the main cause of the increasing eutrophication process in the Baltic Sea during last century. A prerequisite counteract this process the load of nutrients to the Sea must be investigated. The large contribution of nutrients to the Sea is caused by emission from the rivers within the drainage basin. For the total emission of nutrient into the Sea the retention process in the rivers has big influence. This process in the river system has been assumed as a not important part of the nutrient cycle. However some investigators have pointed out that the retention process occurs in the river and be an important part of the nutrient dynamics in the river. For the object of investigation the Odra River Basin was chosen, as an example of a large river basin in the Baltic Sea Drainage Basin. The Odra River is mainly localized in Poland and contributes substantially to the eutrophication of the Baltic Proper. The Odra River is one of the least dammed major rivers of the Baltic Proper and as such of especial interest in retention studies. The phosphorus was chosen as an example of nutrient in the eutrophication process. The purpose of the investigation is to determine the phosphorus retention within the river. Two different models were used to calculate the retention process in the river. The"Multiple Regression Model"turned out to be insignificant, therefore the results were computed by using a “similarity model”, based on similarities between load from monitored tributary basins and the rest of the sub-basin. The retention in the Odra River in the amounted to -4608 t yr-1, which is 43% of the total phosphorus emission to the Odra River. There is also stated that in the Notec and the Warta rivers the retention process occur in the amount of -1940 t yr-1 and -3007 t yr-1 respectively.

  • 58.
    du Preez, Marinus
    et al.
    North-West University, South Africa.
    Govender, Danny
    South African National Parks, South Africa.
    Kylin, Henrik
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Bouwman, Hindrik
    North-West University, South Africa.
    Metallic elements in Nile Crocodile eggs from the Kruger National Park, South Africa2018Inngår i: Ecotoxicology and Environmental Safety, ISSN 0147-6513, E-ISSN 1090-2414, Vol. 148, s. 930-941Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Nile Crocodile is the largest predator on the African continent. Recent mass mortalities in the Kruger National Park (KNP) raised concerns about possible influence of pollution. We analysed eggs and their eggshells collected from nests inside the KNP and from a crocodile farm for metallic elements. We found that mercury, selenium, and copper occurred at levels of concern. Eggshells had very high concentrations of iron. Apart from toxicological implications associated with elevated concentrations in eggs, we found iron possibly contributing towards thicker eggshells. Thicker shells may act as a barrier to gas and water exchange, as well as possibly increasing the effort required for the hatchling to emerge from tightly packed shells under sand. Pollutants are transported into the KNP via rivers, and possibly via air. Mercury and copper pollution are waste-, industrial- and mining-related; ecotoxicological concern should therefore be extended to all areas where the four African crocodile species occur. Reptiles are under-represented in ecotoxicological literature in general, and especially from Africa. We know of only one previous report on metals and metalloids in crocodile eggs from Africa (Zimbabwe), published 30 years ago. Reduced fitness, endocrine disruption and effects on behaviour are other possible sub-lethal effects associated with metallic elements that may only become apparent decades later in a long-lived species such as the Nile Crocodile. In the face of habitat destruction, pollution, human population increases, and climate change, further research is needed regarding pollutant concentrations and effects in all African reptiles . The rivers that carry water from outside the park sustain its aquatic life, but also transport pollutants into the KNP. Therefore, improved source mitigation remains an important task and responsibility for all involved.

    Fulltekst tilgjengelig fra 2019-12-19 15:57
  • 59.
    Ebeman, Bo
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Lennart, PerssonUmeå universitet.
    Size-structured populations: ecology and evolution1988Collection/Antologi (Annet vitenskapelig)
  • 60.
    Ebenman, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Dynamics of age- and size-structured populations: intraspecific competition1988Inngår i: Size-structured populations: ecology and evolution / [ed] Bo Ebenman, Lennart Persson, Berlin: Springer Berlin/Heidelberg, 1988, s. 127-139Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 61.
    Edenborg, Fanny
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Artificial light at night causes advanced initiation of dawn song in songbirds in Linköping, Sweden2018Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
  • 62.
    Ekholm, Sebastian
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Betydelsen av återskapade våtmarkers ålder, area och fiskförekomst för simfåglar: En biologistudie ur ett lärarperspektiv2015Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Återskapade våtmarker är av stor vikt för den biologiska mångfalden och särskilt viktiga för hotade simfåglar. För att öka kunskapen kring hur faktorer som våtmarkers area, ålder och fiskförekomst påverkar simfåglar i återskapade våtmarker studerades fyra våtmarker i Tinnerö naturreservat, Linköpings kommun. Av speciellt intresse var svarthakedoppingen (Podiceps auritus). Antalet svarthakedoppingar i de studerade våtmarkerna hade en positiv utveckling under våtmarkernas första år. Dock minskade antalet svarthakedoppingar i området mellan år 2009 och 2011. År 2011, efter anläggandet av Ekängsdalsgångens våtmarker, stabiliserades antalet igen. Slutsatsen är att nyskapade, fiskfria våtmarker ger goda förutsättningar för hotade arter såsom svarthakedoppingen. Utöver detta undersöktes även de didaktiska möjligheter, utifrån Skolverkets ämnes- och kursplaner för biologi, som exkursioner erbjuder.

  • 63.
    Eklöf, Anna
    et al.
    University of Chicago, Illinois, USA.
    Allesina, Stefano
    University of Chicago, Illinois, USA.
    Networks, Ecological2012Inngår i: Encyclopedia of Theoretical Ecology / [ed] Alan Hastings, Louis Gross, University of California Press, 2012, 1, s. 470-478Kapittel i bok, del av antologi (Fagfellevurdert)
  • 64.
    Eklöf, Anna
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Stouffer, Daniel B.
    Centre for Integrative Ecology, School of Biological Sciences, University of Canterbury, Christchurch 8140, New Zealan.
    The phylogenetic component of food web structure and intervality2016Inngår i: Theoretical Ecology, ISSN 1874-1738, E-ISSN 1874-1746, Vol. 9, nr 1, s. 107-115Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Despite the exceptional complexity formed byspecies and their interactions in ecological networks, such asfood webs, regularities in the network structures are repeat-edly demonstrated. The interactions are determined by thecharacteristics of a species. The characteristics are in turndetermined by the species’ phylogenetic relationships, butalso by factors not related to evolutionary history. Here, wetest whether species’ phylogenetic relationships provides asignificant proxy for food web intervality. We thereafterquantify the degree to which different species traits remainvaluable predictors of food web structure after the base-line effect of species’ relatedness has been removed. Wefind that the phylogenetic relationships provide a significantbackground from which to estimate food web intervalityand thereby structure. However, we also find that thereis an important, non-negligible part of some traits, e.g.,body size, in food webs that is not accounted for by thephylogenetic relationships. Additionally, both these rela-tionships differ depending if a predator or a prey perspectiveis adopted. Clearly, species’ evolutionary history as well astraits not determined by phylogenetic relationships shapes predator-prey interactions in food webs, and the underly-ing evolutionary processes take place on slightly differenttime scales depending on the direction of predator-preyadaptations.

  • 65.
    Eklöf, Anna
    et al.
    Department of Ecology & Evolution, University of Chicago, Chicago, IL, USA; and.
    Tang, Si
    Department of Ecology & Evolution, University of Chicago, Chicago, IL, USA; and.
    Allesina, Stefano
    Department of Ecology & Evolution, University of Chicago, Chicago, IL, USA; and Computatio n Institute, University of Chicago, Chicago, IL, USA.
    Secondary extinctions in food webs: a Bayesian network approach2013Inngår i: Methods in Ecology and Evolution, ISSN 2041-210X, E-ISSN 2041-210X, Vol. 4, nr 8, s. 760-770Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]
    1. Ecological communities are composed of populations connected in tangled networks of ecological interactions. Therefore, the extinction of a species can reverberate through the network and cause other (possibly distantly connected) species to go extinct as well. The study of these secondary extinctions is a fertile area of research in ecological network theory.
    2. However, to facilitate practical applications, several improvements to the current analytical approaches are needed. In particular, we need to consider that (i) species have different ‘a priori’ probabilities of extinction, (ii) disturbances can simultaneously affect several species, and (iii) extinction risk of consumers likely grows with resource loss. All these points can be included in dynamical models, which are, however, difficult to parameterize.
    3. Here we advance the study of secondary extinctions with Bayesian networks. We show how this approach can account for different extinction responses using binary – where each resource has the same importance – and quantitative data – where resources are weighted by their importance. We simulate ecological networks using a popular dynamical model (the Allometric Trophic Network model) and use it to test our method.
    4. We find that the Bayesian network model captures the majority of the secondary extinctions produced by the dynamical model and that consumers’ responses to species loss are best modelled using a nonlinear sigmoid function. We also show that an approach based exclusively on food web structure loses power when species at higher trophic levels are preferentially lost. Because the loss of apex predators is unfortunately widespread, the results highlight a serious limitation of studies on network robustness.
  • 66.
    Ekman Söderholm, Agnes
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Påverkan av Asellus aquaticus (sötvattensgråsugga) på resuspension av partiklar i våtmarker2011Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Anlagda våtmarker i avrinningsområden från jordbruksmarker mottar ofta vatten med höga halter av partikelbunden fosfor. Den viktigaste processen för avskiljning av inkommande partikelbunden fosfor är sedimentation. Resuspension är en process som motverkar netto-sedimentationen av partiklar och kan således minska våtmarkers förmåga att hålla kvar fosfor. Syftet med den här studien var att undersöka om A. aquaticus påverkar resuspensionen av partiklar, och om större tätheter av A. aquaticus orsakar större turbiditet i vattenmassan. Två försök genomfördes i plastakvarier med sediment insamlat från våtmarker anlagda på lerjord. Varje försöksuppställning bestod av en behandling och en kontroll utan några djur. I det första försöket innehöll behandlingen A. aquaticus motsvarande en täthet på 2083 individer m-2 och i det andra försöket en täthet på 500 individer m-2. Turbiditeten mättes med en turbidimeter en gång per dag under sju dygn. Aktiviteten hos A. aquaticus orsakade en signifikant högre turbiditet i vattenmassan i behandlingen än i kontrollen. Turbiditeten var i genomsnitt 161 NTU i akvarier med 2083 individer m-2 och 37 NTU i akvarier med 500 individer m-2. Slutsatsen som drogs är att förekomst av A. aquaticus skulle kunna öka resuspensionen av partiklar i våtmarker. Detta kan i sin tur ha en påverkan på våtmarkers förmåga att hålla kvar fosfor som är bundet till lerpartiklar.

  • 67.
    Engel, Philipp
    et al.
    Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland.
    Kwong, Waldan K.
    Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, USA; Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA.
    McFrederick, Quinn
    Department of Entomology, University of California, Riverside, California, USA.
    Anderson, Kirk E.
    USDA, Carl Hayden Bee Research Center, Tucson, Arizona, USA.
    Barribeau, Seth Michael
    Department of Biology, East Carolina University, Greenville, North Carolina, USA.
    Angus Chandler, James
    Department of Microbiology, California Academy of Sciences, San Francisco, California, USA.
    Cornman, R. Scott
    U.S. Geological Survey, Fort Collins Science Center, Fort Collins, Colorado, USA.
    Dainat, Jacques
    Linköpings universitet, Nationellt superdatorcentrum (NSC). Department of Medical Biochemistry and Microbiology Uppsala University, Uppsala, Sweden.
    de Miranda, Joachim R.
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Doublet, Vincent
    Institute for Biology, Martin Luther University Halle-Wittenberg, Halle, Germany; German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany.
    Emery, Olivier
    Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland.
    Evans, Jay D.
    USDA, ARS Bee Research Laboratory, Beltsville, Maryland, USA.
    Farinelli, Laurent
    Fasteris SA, Switzerland.
    Flenniken, Michelle L.
    Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, Montana, USA.
    Granberg, Fredrik
    Department of Biomedical Sciences and Veterinary Public Health, Virology, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Grasis, Juris A.
    Department of Biology, North Life Sciences, San Diego State University, San Diego, California, USA.
    Gauthier, Laurent
    Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland; Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, USA.
    Hayer, Juliette
    Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Koch, Hauke
    Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA; Royal Botanic Gardens, Kew, Richmond, Surrey, United Kingdom.
    Kocher, Sarah
    Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge , Massachusetts , USA.
    Martinson, Vincent G.
    Department of Biology, University of Rochester, Rochester, New York, USA.
    Moran, Nancy
    Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA.
    Munoz-Torres, Monica
    Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley , California , USA.
    Newton, Irene
    Department of Biology, Indiana University, Bloomington, Indiana, USA.
    Paxton, Robert J.
    Institute for Biology, Martin Luther University Halle-Wittenberg, Halle, Germany; German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany.
    Powell, Eli
    Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA.
    Sadd, Ben M.
    School of Biological Sciences, Illinois State University, Normal, Illinois, USA.
    Schmid-Hempel, Paul
    ETHZ Institut für Integrative Biologie, Zurich, Switzerland.
    Schmid-Hempel, Regula
    ETHZ Institut für Integrative Biologie, Zurich, Switzerland.
    Jin Song, Se
    University of Colorado at Boulder, Boulder, Colorado, USA.
    Schwarz, Ryan S.
    USDA, ARS Bee Research Laboratory, Beltsville, Maryland, USA.
    vanEngelsdorp, Dennis
    Department of Entomology, University of Maryland, College Park, Maryland, USA.
    Dainat, Benjamin
    Agroscope, Swiss Bee Research Centre, Bern, Switzerland; Bee Health Extension Service, Apiservice, Bern , Switzerland.
    The Bee Microbiome: Impact on Bee Health and Model for Evolution and Ecology of Host-Microbe Interactions2016Inngår i: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 7, nr 2, artikkel-id e02164-15Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    As pollinators, bees are cornerstones for terrestrial ecosystem stability and key components in agricultural productivity. All animals, including bees, are associated with a diverse community of microbes, commonly referred to as the micro biome. The bee micro biome is likely to be a crucial factor affecting host health. However, with the exception of a few pathogens, the impacts of most members of the bee microbiome on host health are poorly understood. Further, the evolutionary and ecological forces that shape and change the microbiome are unclear. Here, we discuss recent progress in our understanding of the bee microbiome, and we present challenges associated with its investigation. We conclude that global coordination of research efforts is needed to fully understand the complex and highly dynamic nature of the interplay between the bee micro biome, its host, and the environment. High-throughput sequencing technologies are ideal for exploring complex biological systems, including host-microbe interactions. To maximize their value and to improve assessment of the factors affecting bee health, sequence data should be archived, curated, and analyzed in ways that promote the synthesis of different studies. To this end, the BeeBiome consortium aims to develop an online database which would provide reference sequences, archive metadata, and host analytical resources. The goal would be to support applied and fundamental research on bees and their associated microbes and to provide a collaborative framework for sharing primary data from different research programs, thus furthering our understanding of the bee microbiome and its impact on pollinator health.

  • 68.
    Ericsson, Maria
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Social behaviour responses in red junglefowl (Gallus gallus) selected for tameness2010Independent thesis Advanced level (degree of Master (Two Years)), 40 poäng / 60 hpOppgave
    Abstract [en]

    Historically during domestication of animals, tameness towards humans was likely the most desired trait and therefore bred on. The red junglefowl (Gallus gallus) is the wild progenitor of all domestic chicken breeds and earlier studies present clear morphological, physiological and behavioural differences between domesticated breeds and the non-domesticated red junglefowl. These changes may be the result of altered gene expression - pleiotropy or linked genes. The aim of this thesis was to evaluate (1) effects of tameness selection on social behaviour towards conspecifics and (2) social behaviour differences between the sexes. Two generations of red junglefowl, P0 and its offspring F1, were studied. Both generations were divided into three selection lines (tame, intermediate or fearful), depending on their results in a fear of humans test.  A novel type of social reinstatement test was set up, containing a non-social area without stimulus, and a social area containing a mirror serving as stimulus animals. The social and aggressive behaviours performed towards the mirror were recorded, so was the time spent in the social versus non-social part. An undisturbed behaviour test was performed, as well as a standardized social reinstatement test. The P0-females performed significantly more social behaviour (p=0.008) at 26 weeks than males in the mirror test, and females also displayed significantly more social (p=0.04) and agonistic behaviour (p<0.001) than males in the undisturbed behaviour test. The social reinstatement test displayed a significant effect between the selection lines with regards to sociality. This suggests that there are immediate selection responses in early domestication.

  • 69.
    Eriksson, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Biodiversity at the ecosystem level: structural variation among food webs in temperate and tropical areas2014Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Biodiversity is a fundamental part of the functioning of ecosystems and their ability to provide ecosystem services. It has been shown that a high biodiversity increases the robustness of an ecosystem according to the insurance hypothesis. I propose that a similar effect can be seen on a higher scale, where a high diversity of ecosystem types might stabilize the ecological functionality of a region. By comparing eleven network characters in 70 tropical and temperate ecosystems, their diversity was measured as Euclidean distance between the systems in the 11-dimensional room defined by these characters.  The diversity of ecosystems was shown to be significantly higher in tropical latitudes than in temperate. A possible explanation to this result could be that the higher species diversity in the tropics allows for more types of ecosystems. A higher diversity of ecosystems in a region might indicate a larger amount and variation of possible ecosystem goods and services as well as provide the region with an increased robustness. The measurement of ecosystem diversity between regions might also be of importance in a conservation perspective, where unique and vulnerable ecosystems can be discovered and protected.

  • 70.
    Eriksson, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Diversity of ecosystems: Variation in network structure among food webs2016Independent thesis Advanced level (degree of Master (Two Years)), 40 poäng / 60 hpOppgave
    Abstract [en]

    Biodiversity loss is one of the major threats to humanity. This has led to an increasing amount of research on biodiversity on genetic and species levels. Studies of diversity at the ecosystem level has however been neglected. An important aspect of ecosystems is food webs that describe the predation-prey interactions between species. Properties explaining the topological structure of food webs can be used to compare and highlight differences between ecosystems. In the present study, topological network properties are used to compare the diversity of network structures between groups of empirical food webs. Differences between 45 aquatic and 45 terrestrial food webs are compared as well as the effects of species richness on lake network structure diversity. Network structure diversity is measured as the average Euclidean distance from food webs to their group centroid in a multidimensional space of network properties. While the average network structure differs between aquatic and terrestrial food webs, no significant difference in variation is found. For 128 Swedish and 48 North American lake food webs, increasing species richness is shown to decrease network structure diversity. A higher diversity of network structures could potentially indicate a more ways to cope with disturbances or provisions of a higher variety of ecosystem services. Preliminary tests of ecosystem diversity effects on stability were conducted but proved inconclusive.

  • 71.
    Eriksson, Victor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Effect of land-use history and site-specific environmental factors on solitary bees and flower beetles in clear-cuts of boreal coniferous forest2015Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Land-use history has been recognized as an important factor in shaping biological communities in clear-cuts. Many solitary bees and flower beetles (Cerambycidae: Lepturinae) are commonly found in clear-cuts, which serve as early successional habitats. I analyzed the effect of land-use history on the abundance and species richness, as well as the preference for land-use history in specific species, of solitary bees and flower beetles in coniferous clear-cuts in southern Sweden. Additionally, the effect of site-specific environmental factors was examined. Insects were caught with blue, white and yellow pan-traps in 48 clear-cuts, of which half were meadow and half were forest in the 1870s. With few exceptions, the species found did not show preference for any land-use history. Furthermore, land-use history had no significant effect on the abundance or species richness of solitary bees or flower beetles. This may be due to pan-traps being less attractive in flower-rich locations, a bias in the sampling method. However, species richness and abundance of solitary bees was higher in young clear-cuts (2-4 years old), probably best explained by more exposed soil and higher frequencies of flowering plants in newer clear-cuts. Abundance of flower beetles was higher in old clear-cuts (6-8 years old). This may be due to larger amounts of more strongly decomposed wood in older clear-cuts, which is used in the flower beetles´ larval development. I conclude that solitary bees are likely to benefit if clear-cuts, particularly with meadow history, are kept more open by introducing disturbance regimes, as suggested by previous studies.

  • 72.
    Erkosar, Berra
    et al.
    Univ Lausanne, Switzerland.
    Yashiro, Erika
    Univ Lausanne, Switzerland.
    Zajitschek, Felix
    Uppsala Univ, Sweden; Univ New South Wales, Australia.
    Friberg, Urban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Maklakov, Alexei A.
    Uppsala Univ, Sweden.
    van der Meer, Jan R.
    Univ Lausanne, Switzerland.
    Kawecki, Tadeusz J.
    Univ Lausanne, Switzerland.
    Host diet mediates a negative relationship between abundance and diversity of Drosophila gut microbiota2018Inngår i: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 8, nr 18, s. 9491-9502Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nutrient supply to ecosystems has major effects on ecological diversity, but it is unclear to what degree the shape of this relationship is general versus dependent on the specific environment or community. Although the diet composition in terms of the source or proportions of different nutrient types is known to affect gut microbiota composition, the relationship between the quantity of nutrients supplied and the abundance and diversity of the intestinal microbial community remains to be elucidated. Here, we address this relationship using replicate populations of Drosophila melanogaster maintained over multiple generations on three diets differing in the concentration of yeast (the only source of most nutrients). While a 6.5-fold increase in yeast concentration led to a 100-fold increase in the total abundance of gut microbes, it caused a major decrease in their alpha diversity (by 45-60% depending on the diversity measure). This was accompanied by only minor shifts in the taxonomic affiliation of the most common operational taxonomic units (OTUs). Thus, nutrient concentration in host diet mediates a strong negative relationship between the nutrient abundance and microbial diversity in the Drosophila gut ecosystem.

  • 73.
    Eroukhmanoff, F
    et al.
    Section for Animal Ecology, Lund University, Lund, Sweden.
    Hargeby, Anders
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Arnberg, N N
    Department of Ecology & Evolutionary Biology, University of California, Santa Cruz, CA, USA.
    Hellgren, O
    The EGI, Department of Zoology, Oxford, UK.
    Bensch, S
    Section for Animal Ecology, Lund University, Lund, Sweden.
    Svensson, E I
    Section for Animal Ecology, Lund University, Lund, Sweden.
    Parallelism and historical contingency during rapid ecotype divergence in an isopod2009Inngår i: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 22, nr 5, s. 1098-1110Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent studies on parallel evolution have focused on the relative role of selection and historical contingency during adaptive divergence. Here, we study geographically separate and genetically independent lake populations of a freshwater isopod (Asellus aquaticus) in southern Sweden. In two of these lakes, a novel habitat was rapidly colonized by isopods from a source habitat. Rapid phenotypic changes in pigmentation, size and sexual behaviour have occurred, presumably in response to different predatory regimes. We partitioned the phenotypic variation arising from habitat (selection: 81-94%), lake (history: 0.1-6%) and lake x habitat interaction (unique diversification: 0.4-13%) for several traits. There was a limited role for historical contingency but a strong signature of selection. We also found higher phenotypic variation in the source populations. Phenotype sorting during colonization and strong divergent selection might have contributed to these rapid changes. Consequently, phenotypic divergence was only weakly influenced by historical contingency.

  • 74.
    Eroukhmanoff, Fabrice
    et al.
    Section for Animal Ecology, Ecology Building, Lund University, Lund, Sweden.
    Hargeby, Anders
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Svensson, Erik I
    Section for Animal Ecology, Ecology Building, Lund University, Lund, Sweden.
    Rapid adaptive divergence between ecotypes of an aquatic isopod inferred from F-ST-Q(ST) analysis2009Inngår i: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 18, nr 23, s. 4912-4923Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Divergent natural selection is often thought to be the principal factor driving phenotypic differentiation between populations. We studied two ecotypes of the aquatic isopod Asellus aquaticus which have diverged in parallel in several Swedish lakes. In these lakes, isopods from reed belts along the shores colonized new stonewort stands in the centre of the lakes and rapid phenotypic changes in size and pigmentation followed after colonization. We investigated if selection was likely to be responsible for these observed phenotypic changes using indirect inferences of selection (F-ST-Q(ST) analysis). Average Q(ST) for seven quantitative traits were higher than the average F-ST between ecotypes for putatively neutral markers (AFLPs). This suggests that divergent natural selection has played an important role during this rapid diversification. In contrast, the average Q(ST) between the different reed ecotype populations was not significantly different from the mean F-ST. Genetic drift could therefore not be excluded as an explanation for the minor differences between allopatric populations inhabiting the same source habitat. We complemented this traditional F-ST-Q(ST) approach by comparing the F-ST distributions across all loci (n = 67-71) with the Q(ST) for each of the seven traits. This analysis revealed that pigmentation traits had diverged to a greater extent and at higher evolutionary rates than size-related morphological traits. In conclusion, this extended and detailed type of F-ST-Q(ST) analysis provides a powerful method to infer adaptive phenotypic divergence between populations. However, indirect inferences about the operation of divergent selection should be analyzed on a per-trait basis and complemented with detailed ecological information.

  • 75.
    Eroukhmanoff, Fabrice
    et al.
    Section for Animal Ecology, Ecology Building, Lund University, Lund, Sweden.
    Hargeby, Anders
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Svensson, Erik I.
    Section for Animal Ecology, Ecology Building, Lund University, Lund, Sweden.
    THE ROLE OF DIFFERENT REPRODUCTIVE BARRIERS DURING PHENOTYPIC DIVERGENCE OF ISOPOD ECOTYPES2011Inngår i: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 65, nr 9, s. 2631-2640Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The question of how diverging populations become separate species by restraining gene flow is a central issue in evolutionary biology. Assortative mating might emerge early during adaptive divergence, but the role of other types of reproductive barriers such as migration modification have recently received increased attention. We demonstrate that two recently diverged ecotypes of a freshwater isopod (Asellus aquaticus) have rapidly developed premating isolation, and this isolation barrier has emerged independently and in parallel in two south Swedish lakes. This is consistent with ecological speciation theory, which predicts that reproductive isolation arises as a byproduct of ecological divergence. We also find that in one of these lakes, habitat choice acts as the main barrier to gene flow. These observations and experimental results suggest that migration modification might be as important as assortative mating in the early stages of ecological speciation. Simulations suggest that the joint action of these two isolating barriers is likely to greatly facilitate adaptive divergence, compared to if each barrier was acting alone.

  • 76.
    Evans, Stephen
    et al.
    North-West University, South Africa; University of Venda, South Africa.
    Cole, Nick
    Durrel Wildlife Conservation Trust, Jersey, Channel Islands;Mauritian Wildlife Foundation, Mauritius.
    Kylin, Henrik
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten. North-West University, South Africa.
    Choong Kwet Yive, Nee Sun
    University of Mauritius, Mauritius.
    Tatayah, Vikash
    Mauritian Wildlife Foundation, Mauritius.
    Merven, Jacques
    Raphaël Fishin Corp., Mauritius.
    Bouwman, Hindrik
    North-West University, South Africa.
    Protection of marine birds and turtles at St Brandon’s Rock, Indian Ocean,requires conservation of the entire atoll2016Inngår i: African Journal of Marine Science, ISSN 1814-232X, Vol. 38, nr 3, s. 317-327Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A survey of seabirds and turtles at St Brandon’s Rock, 400 km north of Mauritius, was undertaken in 2010. We estimated that 1.1 million seabirds comprising seven breeding species and excluding non-breeders were present at the archipelago and we counted 279 turtle tracks and nesting pits of green turtles Chelonia mydas. Hawksbill turtles Eretmochelys imbricata were also present. Analyses of 30 different islets that make up the atoll showed that the seabird species mostly partitioned their use of islets based on islet size, with four species preferring larger islets and two species preferring smaller islets. Alien species introduced historically are still present and other threats, such as shipwrecks, remain. We propose conservation and other measures that should adequately protect the birds, turtles and coral reef by treating the atoll as a system.

  • 77.
    Fischer, Helmut
    et al.
    Limnology/Department of Ecology and Evolution, Uppsala University, Sweden.
    Bergfur, Jenny
    Department of Aquatic Sciences, Swedish Agricultural University, Sweden.
    Goedkoop, Willem
    Department of Aquatic Sciences, Swedish Agricultural University, Sweden.
    Tranvik, Lars
    Limnology/Department of Ecology and Evolution, Uppsala University, Sweden.
    Microbial leaf degraders in boreal streams: bringing together stochastic and deterministic regulators ofcommunity composition2009Inngår i: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 54, s. 2276-2289Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1. Leaves that fall into the water represent a new habitat for microorganisms to colonise in streams, providing an opportunity to study colonisation and the subsequent regulation of community structure. We explored community composition of bacteria and fungi on decomposing alder leaves in nine streams in central Sweden, and describe their relationship with environmental variables. Succession of the microbial community was studied in one of the streams for 118 days. Microbial community composition was examined by denaturing gradient gel electrophoresis on replicate samples of leaves from each stream.

    2. During succession in one stream, maximum taxon richness was reached after 34 days for bacteria and 20 days for fungi respectively. Replicate samples within this stream differed between each other earlier in colonisation, while subsequently such variation among replicate communities was low and remained stable for several weeks. Replicate samples taken from all the nine streams after 34 days of succession showed striking similarities in microbial communities within-streams, although communities differed more strongly between streams.

    3. Canonical analysis of microbial communities and environmental variables revealed that water chemistry had a significant influence on community composition. This influence was superimposed on a statistical relationship between the properties of stream catchments and microbial community composition.

    4. The catchment regulates microbial communities in two different ways. It harbours the species pool from which the in-stream microbial community is drawn and it governs stream chemistry and the composition of organic substrates that further shape the communities. We suggest that there is a random element to colonisation early in succession, whereas other factors such as species interactions, stream chemistry and organic substrate properties, result in a more deterministic regulation of communities during later stages.

  • 78.
    Fjellander, Gabriella
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Bumblebee abundance decreases with growing amount of arable land at a landscape level2017Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Society depends on bumblebees for the ecosystem service in the pollination of crops. Bumblebee declines have been documented, mostly due to intensification of agriculture and loss of species-rich semi-natural grasslands, an important bumblebee habitat. To conserve bumblebee diversity and the ecosystem service of pollination, it is important to do analyses on multiple spatial scales to see how the intensification of agriculture affects bumblebees at a landscape level. In this study, I related abundance of bumblebees in 476 sites in southern Sweden (total abundance and abundance of declining/non-declining, long-tongued/short-tongued, and species preferring open terrain vs. forest boundaries) to amount of land use types (semi-natural grassland, arable land, forest, water and “other land use”) at 34 spatial scales (radii 100 to 40,000 m). Arable land had a negative effect on total bumblebee abundance at scales from 464 to 10,000 m and forest had a negative effect at scales from 2929 to 5412 m. Semi-natural grassland showed no clear effects – however, the partial regression coefficients were consistently negative. Arable land had a negative effect on non-declining species, long- and short-tongued species and on species preferring forest boundaries at larger scales, e.g. regions dominated by agriculture. Forest had a positive effect at smaller scales on species preferring forest boundaries and a negative effect at larger scales on species preferring open terrain and on declining species. The results suggest that arable land is a non-habitat for bumblebees and that semi-natural grassland does not affect bumblebee abundance at a landscape level.

  • 79.
    Fjälling, Arne
    Linköpings universitet, Institutionen för fysik och mätteknik. Linköpings universitet, Tekniska högskolan.
    Assessment and reduction of the conflicts between commercial fisheries and grey seals (Halichoerus grypus) in Swedish waters2004Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Along with the recovery of the Baltic Sea grey seal population from very low figures in the late 1970 's, there were clear signs of a rapidly increasing conflict between grey seals and fisheries. The set trap fisheries for salmonids seemed to be suffering the worst, but such data as were available were bard to evaluate. This lack of usable data fuelled a heated debate between commercial fishermen and seal biologists; it also made it difficult to take administrative decisions on compensatory programs to fishermen and inhibited research into mitigation methods. Available methods for the calculation of lost catches were imperfect. It was evident that the usual procedure, of simply counting the number of damaged fish found, would not reveal the total losses. It seemed likely that as well as the damaged and stolen fish, there could be other factors which would be negative for the outcome of the fishing operation. Finally, mitigation methods described were few and were said to be largely ineffective.

    A database was therefore built with detailed information on catches and seal disturbance from contracted commercial fishermen. A model was developed for the calculation of seal-induced Josses in salmon set traps. The mode] compared catches on consecutive days, i.e. in day-pairs. It was found that the total catch losses in set traps were high, at above 50% of the potential catch. A significant part of these losses was 'hidden', for example in the form of fish wholly removed from the gear. The mode! was also used for an analysis of the damage process. It was found that there were negative after-effects of seal visits and that increasing seal damage coincided with rising catches. It was suggested that the traditional estimation of damage by counting fish remains should be calibrated when used and that the new mode! with day-pairs should be tried in analyses of seal interference in other fishing operations. Data from the new model, together with logbook data, was then used in an estimation of seal damages to the Swedish fisheries as a whole. The overall losses, of catch plus gear damages, were estimated at over 40 million SEK in 2003.

    An attempt was then made to design a seal-safe salmon trap on the basis of previous observations of seal behaviour. In this experiment a set trap for salmonids was built using a larger mesh than the standard design and then compared with a standard trap. The basic idea was to use meshes small enough to guide an undisturbed fish further into the gear, towards the fish chamber, but large enough to allow a panicking fish being chased by a seal into the net panel to pass through, leaving the seal behind. Seal activity in and around the test trap was found to be only 6% of what it was around the standard trap; the activity level decreased further the following year when only large-meshed traps were used in the area. An estimate indicated that 65% of the potential catch was lost in the standard trap owing to seal predation, while the escape rate through the large meshes in the test trap was 52%. The standard trap had a total of 269 holes owing to seal damage, while only six holes were found in the test trap. A strategy that deprives seals of a reward makes the gear uninteresting to seals and may have long-term mitigation effects.

  • 80.
    Flink, Maria
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ekologi.
    Död ved och förekomsten av två mossor som indikerar skoglig kontinuitet2011Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [sv]

    Studiens syfte är att undersöka arterna Buxbaumia viridis och Nowellia curvifolia för att kunna förutse var man hittar dessa signalarter. Detta gjordes genom att död liggande ved undersöktes i Ycke naturreservat samt en närliggande brukas skog, Östergötlands län.

    Resultaten visar att faktorerna som är avgörande för B. virids är markkontakt och nedbrytningsklass. B. viridis föredrar att växa på lågor i de högre nedbrytningsklasserna (4-7) och med stor andel markkontakt, över 80 %. N. curvifolia beror på diameter (över 60cm), nedbrytningsklass (3-4) och längd (över 30m). Baserat på dessa resultat, kan signalarter lättare upptäckas utan en fullskalig inventering av skogen.

  • 81.
    Florentine, SK
    et al.
    Centre for Environmental Management, Faculty of Science and Technology, Federation University Australia, PO Box 663, Victoria 3350, Australia.
    Milberg, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten. per.milberg@liu.se.
    di Stefani, Julian
    Department of Ecosystem and Forest Sciences, University of Melbourne, 4 Water St Creswick, Victoria 3363, Australia.
    Westbrooke, Martin
    Centre for Environmental Management, Faculty of Science and Technology, Federation University Australia, PO Box 663, Victoria 3350, Australia.
    Graz, Patrick
    Centre for Environmental Management, Faculty of Science and Technology, Federation University Australia, PO Box 663, Victoria 3350, Australia.
    Decade-long response of arid-land mallee vegetation to fire, flooding and grazing in south-eastern Australia2015Inngår i: Journal of Arid Environments, ISSN 0140-1963, E-ISSN 1095-922X, Vol. 121, s. 7-14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Australian arid vegetation has evolved within highly variable environments characterised by low rainfall and sporadic fire events. Episodic high rainfall events are a significant factor in plant species recruitment, but their unpredictability makes them difficult to study. We report on the response of vascular plants to a major rainfall event and flood in an arid region of south-eastern Australia. Fire that occurred two months before the flood was incorporated into the study. Paired fenced and unfenced plots were established at control locations and also in areas that had been either flooded, burnt, or flooded and burnt. Objectives were to quantify the long-term effects of fire, flood and vertebrate herbivory, and their interactions, on vegetation composition, plant life forms and species diversity. We found that relative to controls (i) there was a significant effect of flooding on vegetation composition, (ii) changes in life form abundance were driven by flooding and grazing, (iii) there was a strong positive relationship between grazer exclusion and species diversity that was maintained over time and (iv) there was little effect of fire. Understanding the long-term effects of both natural disturbances and vertebrate herbivory will benefit plant conservation in the arid zone.

  • 82.
    Forsman, Hanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Hur påverkas kransalgen Chara globularis, vattengråsugga, Asellus aquaticus och påväxtalger av kalkning i en eutrof sjö?2018Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [sv]

    Grunda, näringsrika sjöar förekommer i två stadier: antingen ett med grumligt vatten och hög biomassa av växtplankton, eller ett med klart vatten och riklig undervattensvegetation. Det klara stadiet är eftersträvansvärt eftersom det skapar goda förutsättningar för en rad ekosystemtjänster, inklusive vattenkvalitet, rekreation och förutsättningar för biodiversitet. Vid eutrofiering, d v s ökat tillskott av näringsämnen, kvarstår det klara stadiet tills näringsbelastningen blir så hög att sjön övergår till ett grumligt stadium. Sjön Tåkern, i Östergötland, har under de senaste åren blivit alltmer eutrofierad och kalkning av vattnet har diskuterats som en möjlig åtgärd för att bevara det klara stadiet som sjön numera befinner sig i. Undersökningar om kalkning av eutrofierade sjöar har gjorts tidigare, men det har varit få studier av effekterna av kalkning på undervattensvegetation, substratlevande djur och påväxtalger. För att undersöka detta, gjordes ett fält- och ett laboratorieexperiment inriktade på effekter på överlevnad av vattengråsugga, Asellus aquaticus, fysiologisk status (halten klorofyll a) i kransalgen Chara globularis och tillväxt av nyetablerade påväxtalger i sjön Tåkern. Resultaten visar att A. aquaticus hade lägre överlevnad efter kalkning till pH 10 i laboratorieexperiment, men i fältförsöket hade kalkning till detta pH inte någon inverkan. C. globularis hade en högre halt klorofyll a efter kalkning till pH 10 i laboratorieexperimentet, men i fältexperimentet hade kalkning ingen effekt på halten klorofyll a. Påväxtalger hade en lägre tillväxthastighet efter kalkning i fältexperimentet. Slutsatsen är att kalkning kan vara en metod för att motverka eutrofiering av sjön Tåkern. Några inkonsekvenser mellan mesokosm- och laborationsresultaten tyder på att fler studier behövs göras för att undersöka hur kalkning till pH 10 påverkar bentiska organismer. 

  • 83.
    Fraissard, camille
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Zoologi.
    Experimental release of hand-reared wolf pups in Tver region (Russia): food habits, movement patterns and fear of humans.2011Independent thesis Advanced level (degree of Master (Two Years)), 60 poäng / 90 hpOppgave
    Abstract [en]

    Studying the reintroduction of hand-raised wolves may embrace several interests such as deepening knowledge on wolf biology and allowing a controlled release in isolated populations in need of genetic influx. Studies on hand-raised wild animals, showing successful reintroduction, suggested that young released wolves might be able to survive in the wild without previous fastidious training. Most of their survival behaviours would be instinctive. In this study, nine young wolves were reintroduced in Tver region (Russia) and followed in order to evaluate their fear of humans, their movement patterns, thanks to GPS-Argos collars fitted to three of the animals, and assess their diet via four methods of scats analysis. We analyzed 46 wolf scats collected from August 2010 to January 2011. We determined the frequency of occurrences of items per scats and per items, and used the Relative Estimated Bulk to estimate the biomass of prey species consumed. Statistics were conducted to test for significance of method comparisons. The results showed that half of the wolves remained near the enclosure weeks to months after release, occasionally leaving the vicinity. The individual wolves behaved differently, they adopted various movement patterns and had diverse home ranges (from 15 km2 to 40 km2). Released wolves preyed more on ungulates, especially moose and on other wild mammals such as mountain hare. They also sporadically hunted domestic animals and regularly consumed vegetal matter along with smaller animals as alternative prey. Finally, all scat-analysis methods significantly assessed (p < 0.01) the relative importance of the main food types.

  • 84.
    Fredriksson, Karin
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Landskap, förvaltning ochbiologisk mångfald: - En studie av styrd okument och insektsochfågeldiversitet, i två naturreservat med olika ägare.2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Det finns tydliga bevis på att jorden idag är dominerad av människor(Vitousek et al. 1997). Den biologiskamångfalden i tätortsnära naturområden är beroende av att befintliga habitat fortsätter att existera samt attpopulationskorridorer mellan olika habitatområden bevaras eller återställs. I denna studie undersöks kopplingenmellan biologisk mångfald i tätortsnära naturreservat och dokumentation avsedd att styra förvaltningen av dessaområden. Skillnader i biologisk mångfald, samt skillnader i utformningen av styrdokument mellan naturreservatenNorrköpings ekbackar och Tinnerös eklandskapundersöktes. För att uppnå detta, genomfördes fältinventering avinsekts- och fågelpopulationer, samt en innehållsanalys av styrdokument för naturreservaten. Studien utfördes i tvåliknande naturreservat i Östergötland, av naturtyp eklandskap. De undersökta områdena har en likartad historisktmarkanvändning. Båda undersökningsområden är tätortsnära med mänsklig aktivitet runt och inom området.Resultaten från fältinventeringarna visade ingen statistisk signifikant skillnad mellan områdena i tre olikadiversitetsmått; antal arter, Simpsons diversitetsindex samt Shannon-Wieners diversitetsindex gällandeinsektspopulationer. Fågelinventeringarna visade en statistisk signifikant skillnad i antal arter, men ingen statistisksignifikant skillnad i Simpsons diversitetsindex eller Shannon-Wieners diversitetsindex mellanundersökningsområdena. Resultatet från innehållsanalysen av styrdokument visade skillnader i hur värden inomområden framställs och vilka hänsynstaganden som föreslagen utveckling anses bör ta till dessa. Studien visar att ettindirekt samband finns mellan styrdokument och biologisk mångfald samt att skillnader i utformning av styrdokumentkan ge konsekvenser för framtida biologisk mångfald.

  • 85.
    Friberg, Nikolai
    et al.
    Department of Bioscience, Aarhus University, Silkeborg, Denmark.
    Bergfur, Jenny
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Rasmussen, Jes
    Department of Bioscience, Aarhus University, Silkeborg, Denmark.
    Sandin, Leonard
    Changing Northern catchments: Is altered hydrology, temperature or both going to shape future stream communities and ecosystem processes?2013Inngår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 27, nr 5, s. 734-740Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Global change is predicted to increase temperature substantially in the North as well as altering run-off regimes with less synchronicity as the importance of snow melt declines. River biota and ecosystem processes will be influenced across all levels of organization, both in concert and individually. It is of vital importance that the impacts, and their likely magnitude, can be identified in order to deploy suitable adaptation strategies at the catchment scale. In this paper, we re-analyse four data sets from studies conducted in Greenland (66–69oN), Iceland (64oN), Sweden (60oN) and Denmark (55–57oN) to try and tease out the likely impacts of water temperature and hydrology in shaping the stream communities and ecosystem processes in high-latitude catchments. Water temperature was the environmental variable that best explained macroinvertebrate community composition across latitudes. In contrast, no significant relationship between macroinvertebrate community composition and measures of hydraulic stability (or nutrients) was found. We found a strong linear relationship between decay rate of leaf litter and water temperature (r2 = 0.68; p < 0.0001) independent of latitudes. Our study suggests that temperature could be the primary driver of ecosystem change in future with northern catchments likely to be especially vulnerable.

  • 86.
    Fridström, Malin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ekologi.
    Betydelsen av anlagda våtmarkers area och ålder för förekomst av sjöfågel inom Linköpings kommun2011Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    The aim of this study was to examine what impact restored and constructed pounds and wetlands have on waterfowls in the area of Linköping. The birdlife in five constructed wetlands werechosen to investigate if specific factors like age, size and vegetation affected the avian diversity in wetlands. Also, extra focus has been given to the threatened Horned Grebe (Podiceps Auritus), breeding in the studied area. The results showed that the number of species as well as individuals of waterfowl and Horned Grebe changed over time in what might be a result of succession in the wetlands. Comparing the number of birds to the size of the wetlands showed a clear correlation. Larger areas inhabited greater numbers of species and individuals. However, the Horned Grebe showed a reverse result, as they seem to prefer smaller wetlands. Finally, a correlation between the numbers of observed Black-headed gulls and Horned Grebes could be found. When there was a greater number of Horned Grebes observed there was also a greater numbers of gulls present. Possibly the Horned Grebe takes advantage of the Black-headed gull-colony for protection against predators. 

  • 87.
    Galin, Isolde
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    How former arable fields with permanent grazing differ from managed semi-natural pastures in Sweden2019Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    New farming needs and innovations have, over time, led to changes in land use. Arable fields have been turned into pastures and semi-natural pastures into arable fields. Due to the ecological value of continually grazed semi-natural pastures in Sweden the aim of this study is to find out how former arable fields that are permanently grazed differ from semi-natural pastures. In this study I selected appropriate semi-natural pastures from a national monitoring program on seminatural- pastures and meadows. Plots continuously grazed were compared with grazed plots on former arable fields. Pair-wise differences in the Ellenberg indicator values Light (L), Soil moisture (F), soil pH (R) and soil nitrogen (N), vertical coverage of trees, bushes and vegetation, species richness and species composition were tested. Except for species composition there were only small differences between former arable fields that are permanently grazed and semi-natural pastures. That means former arable fields can with time and grazing gain many of the values continuously grazed semi-natural pastures have.

  • 88.
    Generó, Magalí Martí
    et al.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Juottonen, Heli
    MEM-group, Department of Biosciences, University of Helsinki, Helsinki, Finland.
    Robroek, Bjorn J.M.
    Ecology and Biodiversity Group, Institute of Environmental Biology, Utrecht University, CH Utrecht, The Netherlands.
    Yrjälä, Kim
    MEM-group, Department of Biosciences, University of Helsinki, Helsinki, Finland.
    Danielsson, Åsa
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Lindgren, Per-Eric
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för mikrobiologi och molekylär medicin. Linköpings universitet, Hälsouniversitetet.
    Svensson, Bo
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Nitrogen and methanogen community composition within and among three Sphagnum dominated peatlands in Scandinavia2015Inngår i: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 81, s. 204-211Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ombrotrophic raised bogs are nutrient poor acidic peatlands accumulating organic matter. They are widely spread on northern latitudes and are substantial sources of methane emissions to the atmosphere being of great concern from a climate change perspective. We investigated the methanogen community composition along microtopographic gradients within three bogs in Scandinavia, receiving different amounts of nitrogen precipitation. Methanogenic community analyses by terminal restriction fragment length polymorphism of the mcrA gene showed different profiles among the three sites, while no in- fluence of the microtopographic gradients was observed. Peat temperature and dissolved organic carbon were the major edaphic variables explaining 38% of the variation of the methanogenic community di- versity among the bogs. The family Methanoregulaceae (hydrogenotrophic methanogens) showed the largest relative proportion and highest activity in all three sites. Quantitative PCR of the mcrA gene and transcripts showed that the most northern site, receiving the lowest atmospheric nitrogen load, had significantly lower abundance and activity of methanogens (4.7 106 and 2.4 104 mcrA copies per gram of soil, respectively), compared to the most southern site (8.2 107 and 4.6 105 mcrA copies per gram of soil, respectively), receiving the highest nitrogen load. No patterns of the mcrA gene and tran- script abundances were observed along the microtopography. The results indicated that the difference in occurrence of methanogens is mainly due to geoclimatological conditions rather than site intrinsic microtopographic variation. The study further suggests that environmental changes on the site intrinsic topography will not affect the methanogenic activity, while increasing average temperatures in Scan- dinavian ombrotrophic raised bogs might contribute to an increase of the methanogenic archaeal activity resulting in an increase of methane production. 

  • 89.
    Gero-Berndtzon, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Hur ser lavars fördelning ut runt stammen på ek, och påverkas den av trädets storlek och dess närmiljö?2013Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    The aim of this study was to describe preferences of geographic direction of ten, oak-living epiphytic lichen species and how they responded to sun exposure, nearby bushes and trees, bark fissure depth and circumference. The frequency of every species was recorded in arcs of ten degrees around the tree at a height of 130 to 180 cm above the ground. An estimation of the amount of every species in every arc was also recorded. To analyse how the distribution of the lichen species responded to the different factors their concentration for every tree was plotted against the four factors. The distribution of Cliostomum corrugatum had a positive response to high sun exposure and a negative response to a thick layer of bushes and trees. However the distribution of Lepraria incana had a negative response to high sun exposure and a positive response to a thick layer of bushes and trees. Only the distribution of Calicium viride had a significant response to the circumference of the tree. No species had a significant response to the bark fissure depth in this study. For the conservation of the rare C. corrugatum, oaks on which the species is growing should be cleansed from nearby bushes and trees to increase the sun exposure.

  • 90.
    Gilljam, David
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Metapopulation persistence of insects living in hollow oaks: effects of adding oaks in  the surrounding landscape2009Independent thesis Advanced level (degree of Master (Two Years)), 40 poäng / 60 hpOppgave
    Abstract [en]

    The oak district of Östergötland is one of the largest oak forests left in Europe and it harbours many threatened species dependent on old hollow trees. In this study, the saproxylic beetle Osmoderma eremita living in hollow oaks was used as a model species and parameterised for a metapopulation model (the incidence function model) at the level of individual trees. The aim was to set up a number of conservation management scenarios, where new oaks were added to increase the quality of the matrix and then simulate the resulting metapopulation occupancy, using three levels of dispersal. A real data set of hollow oaks was used as the base for modeling. Oaks were added to cells in a lattice covering the study landscape, where cell size, cell position and numbers of oaks per hectare were varied. The results show that a larger area of added oaks and a greater number of oaks per hectare will give a higher increase in total occupancy, no matter the dispersal, but the second smallest cell size used (3.4 km2 ) will give the highest response per effort for medium and high dispersal abilities, and smaller cells with greater number of oaks per area can be more effective. The spatial position of the increase in occupancy differs depending on dispersal ability of the focal species and should be considered in conservation management work. For unoccupied cells, the effort required to get the cell occupied will be smaller for cells having a greater number of oaks.

  • 91.
    Godoy, Erika
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Effects of the captive environment and enrichment on the daily activity of European Bison (Bison bonasus)2009Independent thesis Advanced level (degree of Master (Two Years)), 40 poäng / 60 hpOppgave
    Abstract [en]

    When breeding wild species in captivity, the animals may gradually become more adapted to captivity and therefore less suited for reintroduction which is the ultimate goal for some species. This study measured the activity budget of European bison (Bison bonasus) in six enclosures in Sweden with the aim to find out how the characteristics of the enclosures – with and without pasture - influenced the activity budget. The results show that there were significant differences in the activity budget, i.e. the activity was higher in the enclosures with pasture than in enclosures with barren ground. However, since barren enclosures were smaller than naturalistic, it was not possible to exclude the effect of size. Judged from observations of bison in the wild, there seems to be a direct correlation between food availability and ranging, indicating that enclosure characteristics affect activity more than size. The bison foraged differently in the two enclosure categories, but the total amount of time spent on feeding did not differ. A feeding enrichment experiment showed to have more positive effects in the barren enclosures than in the naturalistic ones, as the amount of time of inactivity decreased in the former. Since the genetic characteristics of all Swedish bison are very similar, the differences between the two enclosure groups indicate that the animals still have the ability to respond appropriately to improved environmental quality. Hence the next step in the assessment of the suitability of these bison for release would be to study them during an acclimatisation program.

  • 92.
    Goug, Leonie A.
    et al.
    Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, Aas NO-1432, Norway, Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, SL5 7PY, United Kingdom.
    Sverdrup-Thygeson, Anne
    Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, Aas NO-1432, Norway.
    Milberg, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Pilskog, Hanne E.
    Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, Aas NO-1432, Norway.
    Jansson, Nicklas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Jonsell, Mats
    Department of Ecology, Swedish University of Agricultural Sciences, Box 7044, Uppsala SE-750 07, Sweden.
    Birkemoe, Tone
    Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, P.O. Box 5003, Aas NO-1432, Norway.
    Specialists in ancient trees are more affected by climate than generalists2015Inngår i: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 5, nr 23, s. 5632-5641Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ancient trees are considered one of the most important habitats for biodiversityin Europe and North America. They support exceptional numbers of specializedspecies, including a range of rare and endangered wood-living insects. In thisstudy, we use a dataset of 105 sites spanning a climatic gradient along the oakrange of Norway and Sweden to investigate the importance of temperature andprecipitation on beetle species richness in ancient, hollow oak trees. We expectedthat increased summer temperature would positively influence all wood-livingbeetle species whereas precipitation would be less important with a negligible ornegative impact. Surprisingly, only oak-specialist beetles with a northern distributionincreased in species richness with temperature. Few specialist beetles and nogeneralist beetles responded to the rise of 4°C in summer as covered by our climaticgradient. The negative effect of precipitation affected more specialist speciesthan did temperature, whereas the generalists remained unaffected. In summary,we suggest that increased summer temperature is likely to benefit a few specialistbeetles within this dead wood community, but a larger number of specialists arelikely to decline due to increased precipitation. In addition, generalist species willremain unaffected. To minimize adverse impacts of climate change on this importantcommunity, long-term management plans for ancient trees are important.

  • 93.
    Grafström, Amanda
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Hur biodiversitet på ekosystemnivå skiljer sig mellan olika habitat2014Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Biodiversity can be described as the total variation of life forms, where diversity ranges from gene level up to the ecosystem level. The diversity can be calculated in a number of ways, and this study use one of these methods. In this study empirical food webs have been used and analyzed, where eleven characters are defined and used as parameters to calculate the Euclidean distances between food webs that describe the variation that may exist within classes of terrestrial, marine and freshwater habitats. The class who stood out and showed the greatest diversity at the ecosystem level was the marine food webs, which showed a high value of the average euclidean distance. The other networks were not as distinctive and the average of the euclidean distance in these classes was comparatively low.

  • 94.
    Grasset, Charlotte
    et al.
    Univ Fed Juiz de Fora, Brazil; Uppsala Univ, Sweden.
    Mendonca, Raquel
    Univ Fed Juiz de Fora, Brazil; Uppsala Univ, Sweden.
    Saucedo, Gabriella Villamor
    Univ Fed Juiz de Fora, Brazil; Uppsala Univ, Sweden.
    Bastviken, David
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Roland, Fabio
    Univ Fed Juiz de Fora, Brazil.
    Sobek, Sebastian
    Uppsala Univ, Sweden.
    Large but variable methane production in anoxic freshwater sediment upon addition of allochthonous and autochthonous organic matter2018Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 63, nr 4, s. 1488-1501Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An important question in the context of climate change is to understand how CH4 production is regulated in anoxic sediments of lakes and reservoirs. The type of organic carbon (OC) present in lakes is a key factor controlling CH4 production at anoxic conditions, but the studies investigating the methanogenic potential of the main OC types are fragmented. We incubated different types of allochthonous OC (alloOC; terrestrial plant leaves) and autochthonous OC (autoOC; phytoplankton and two aquatic plants species) in an anoxic sediment during 130 d. We tested if (1) the supply of fresh alloOC and autoOC to an anoxic refractory sediment would fuel CH4 production and if (2) autoOC would decompose faster than alloOC. The addition of fresh OC greatly increased CH4 production and the delta C-13-CH4 partitioning indicated that CH4 originated exclusively from the fresh OC. The large CH4 production in an anoxic sediment fueled by alloOC is a new finding which indicates that all systems with anoxic conditions and high sedimentation rates have the potential to be CH4 emitters. The autoOC decomposed faster than alloOC, but the total CH4 production was not higher for all autoOC types, one aquatic plant species having values as low as the terrestrial leaves, and the other one having values as high as phytoplankton. Our study is the first to report such variability, suggesting that the extent to which C fixed by aquatic plants is emitted as greenhouse gases or buried as OC in sediment could more generally differ between aquatic vegetation types.

  • 95.
    Gudmundson, Sara
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Species Responses to Environmental Fluctuations: impacts of food web interactions and noise color2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Species constantly experience changes in their environmental conditions owing to natural or human induces reasons. Understanding how species respond to these fluctuations are important for ecology, especially given the ongoing climate change. Empirical studies have shown that species respond differently to the same disturbance. However, our knowledge of what create these differences in the environmental response is limited and in most cases based on studies focusing on single species. In this thesis, I have taken a theoretical approach and used dynamical models to investigate how the population dynamics of species are affected by species-species interactions and environmental fluctuations.

     

    In the first paper (Paper I) I investigated how a species respond to environmental fluctuations when isolated or embedded in a food web. The study showed that species-species interactions had an effect in temporally positively autocorrelated environments (red noise) but not in uncorrelated environments (white noise). This was owing to species following their equilibrium densities in red environments which in turn enabled species-species interactions to come into play. Red environmental variables are more prominent in nature than white. Thus, these results show the importance of using a food web approach when analyzing species response to environmental fluctuations.

     

    The most commonly discussed effect of climate change is an elevated mean temperature. This shift is expected to affect the growth rate of many species. However, there is no robust theory of how we should expect species in food webs to respond to a rise in temperature. In the second paper (Paper II) I defined and studied the dynamic rate of food webs

    (DR) acting analogously to single species growth rate. I found that the higher DR the easier for species population densities to follow their equilibrium over time. Both DR and noise color changed the temporal relationship between the population and the environmental noise. Thus, it is of major importance to take the scale of time into consideration when investigating species response to environmental fluctuations.

     

    Another important factor which affect population dynamics is species spatial distributions. Dispersal between subpopulations enable individuals to rescue or prolong the time to extinction for the population seen as a whole. In the third paper (Paper III), I investigated how species in food webs respond to environments that varies both in time and space and compared the results with the one from single species. I found that single species were stabilized by an increased dispersal rate independent of the noise color. Species-species interactions had an effect for some of the species in these landscapes.

    At red asynchronous noise, one resource species in each food web had a local minimum in stability at low dispersal rate. Here, dispersal decoupled local population dynamics and prevented species from tracking their equilibriums. At high dispersal rates, all resource species and their single species counterparts were stabilized by dispersal as local patch dynamics lost its importance. Environmental noise together with the spatial dimension does seem to explain much of the stability properties of species on our planet.

     

    However, natural ecosystems are much more complex and species rich than the food web models I have used so far. Theoreticians have previously had a hard time describing stable complex systems that survive environmental fluctuations. Thus, in my fourth and last project (Paper

    IV) I investigated how species population dynamics are affected by environmental fluctuations when embedded in larger food webs. These systems were built by connecting food web modules with periodic boundary conditions (PBC). The PBC method has previously helped physicists to understand the nature of waves and particles by removing the edges in systems. I found that food web size does not have to have a negative effect on food web stability. I showed that by removing the destabilizing effect of edges it is possible to describe large stable food webs, more similar to natural ecosystems.

     

    Overall, the research presented here give new insights into species responses to environmental fluctuations. They especially highlight the importance of considering both species interactions and environmental noise color when studying population dynamics in a fluctuating environment. A food web approach is necessary when analyzing species population dynamics and planning for conservation actions, especially when studying the effects of climate change on biodiversity.

    Delarbeid
    1. Environmental variability uncovers disruptive effects of species interactions on population dynamics
    Åpne denne publikasjonen i ny fane eller vindu >>Environmental variability uncovers disruptive effects of species interactions on population dynamics
    2015 (engelsk)Inngår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 282, nr 1812, s. 67-75Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    How species respond to changes in environmental variability has been shown for single species, but the question remains whether these results are transferable to species when incorporated in ecological communities. Here, we address this issue by analysing the same species exposed to a range of environmental variabilities when (i) isolated or (ii) embedded in a food web. We find that all species in food webs exposed to temporally uncorrelated environments (white noise) show the same type of dynamics as isolated species, whereas species in food webs exposed to positively autocorrelated environments (red noise) can respond completely differently compared with isolated species. This is owing to species following their equilibrium densities in a positively autocorrelated environment that in turn enables species species interactions to come into play. Our results give new insights into species response to environmental variation. They especially highlight the importance of considering both species interactions and environmental autocorrelation when studying population dynamics in a fluctuating environment.

    sted, utgiver, år, opplag, sider
    ROYAL SOC, 2015
    Emneord
    environmental autocorrelation; environmental tracking; food webs; indirect effects; paradox of enrichment; population stability
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-122442 (URN)10.1098/rspb.2015.1126 (DOI)000362305500008 ()26224705 (PubMedID)
    Merknad

    Funding Agencies|Linkoping University

    Tilgjengelig fra: 2015-11-03 Laget: 2015-11-02 Sist oppdatert: 2017-12-01
  • 96.
    Gudmundson, Sara
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Institutionen för fysik, kemi och biologi, Ekologi.
    Stabilizing factors in spatially structured food webs2009Independent thesis Advanced level (degree of Master (Two Years)), 40 poäng / 60 hpOppgave
    Abstract [en]

    Ecological models have problems showing the positive relationship between diversity and stability found in nature. Theory states that complex food webs have high extinction risks and low stability. However, persistent food webs found in nature are large and complex containing many interconnections between species. There are many possible mechanisms enabling persistent food webs such as; complex interaction patterns, asynchronous fluctuations of species densities, environmental fluctuations and spatial distribution. These factors have not been used in classical models. In this study, coloured environmental 1/f noise and dispersal between subpopulations were incorporated into a diamond shaped food web based on a model by Vasseur and Fox 2007. Contradictions between theoretical and empirical results regarding food webs can be resolved by detailed analyses of models, withholding stabilizing mechanisms. Weak environmental 1/f noise generated an increased coefficient of stability but the stabilizing effect of noise can be questioned because of a decreased mean food web biomass and reduced stabilizing effect when reddened. However, detailed studies of the food web revealed that noise can redistribute density proportions between species, evading lowest species density and thereby increase food web resistance to demographic stochasticity and catastrophes. Noise induced density proportion shifts imply that large population sizes are no insurance towards future increase in environmental variance. Synchrony of species environmental responses and dispersal between subpopulations can both have major influences on stability and extinction risk of smaller food webs indicating that spatial structure could be one of the dominating factors stabilizing complex food webs found in nature.

  • 97.
    Gunneng, Vibeke
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Butterfly monitoring in Sweden reveals changes in occurrences over a five-year period2015Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Many of the European butterfly species have declined rapidly over the past decades. The cause is thought to be habitat loss due to factors such as increased tree cover, afforestation and intensified agriculture. I analyzed nation-wide data on butterfly occurrences in Sweden, to explore whether occurrences of individual species, grassland dependent species, grassland specialists, red-listed species, and moths, have increased or declined over a period of five years. I found that four species had significantly declined and eight had increased. The results were in accordance with other finds from Sweden, as well as from the UK, regarding the declining species. In contrast, the results regarding the increasing species only partly confirmed previous studies. I also found that grassland specialists and red-listed species had increased, possibly reflecting the fact that Sweden has a relatively large amount of boreal landscapes containing patches of clear-cuts and semi-natural grasslands.

  • 98.
    Gustafsson, Jannie Frida Linn
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Thermoregulatory behavior and habitat use of Liolaemus aparicioi at two different altitudes2015Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    The thermoregulation of lizards depends highly on the environment they inhabit. Thermoregulation is crucial for physiological processes and affects therefore the life history of the lizard. High altitudes are characterized by a colder climate than on lower altitudes, and these environmental factors affects the thermoregulation of lizards. Lizards can however adapt to colder climates by adjusting their physiology and/or behavior. In this study two populations of Liolaemus aparicioi, an endemic lizard inhabiting the valleys close to La Paz, were observed at two different altitudes to investigate any differences in behavior or habitat use that could compensate for the high altitude. The behavioral displays associated to thermoregulation and the use of habitat were recorded in order to assess how they allocated their time and how they used the habitat available. The mean values of most parameters measured indicated that the population on the high altitude do compensate for the high altitude by behavior and habitat use.

  • 99.
    Gustafsson, Jennie Frida Linn
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Traits and habitat specialization influence in future range shifts of butterflies in a warmer climate2017Independent thesis Advanced level (degree of Master (Two Years)), 40 poäng / 60 hpOppgave
    Abstract [en]

    Climate change is considered one of the greatest future threats against biodiversity. One predicted consequence of a global temperature increase is that biomes will move against the poles, which will force species to either adapt to an unsuitable habitat or follow their climatic range shift. A common way to assess the future geographical distribution of a species is to predict their future climatic range. However, this excludes factors that could interfere with the species ability to follow their range shift, such as dispersal ability. The importance of expansion-related traits are often assumed rather than quantified. This study investigated if the specialist butterfly Pyrgus armoricanus, living at its northern range limit in south Sweden, will be able to expand north as the temperature increases. The study also explored the importance of six traits on a butterfly’s range shift ability; habitat specialization, growth rate, emigration probability, establishment probability, dispersal vagrancy and dispersal probability. The study found that the butterfly Pyrgus armoricanus will not be able to expand north in Sweden due to low dispersal ability and habitat availability. The most important traits for a butterfly’s ability to expand north in Sweden was growth rate, dispersal ability and habitat generalisation. Specialized butterflies dependent on well managed meadows will have limited success in following their northern range limit, and restoration is necessary to avoid future biodiversity degradation.

  • 100.
    Gustavsson, Maria
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Kalkningseffekter på plankton: ett mesokosmexperiment i den kalkrika sjön Tåkern2015Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    One of today's major environmental issues is algal blooms linked to eutrophication of lakes and oceans. That is a result of anthropogenic influence with nutrient loads (including phosphorus) from agriculture and industry, which benefits primary production (phytoplankton). Studies have shown that phosphorus availability in the water column can be limited by liming, therefore could be a way to counteract eutrophication. This was tested in the agriculturally surrounded lake Tåkern in southern Sweden, which in its present state is an internationally important bird lake and therefore in several respects would be affected by eutrophication. The purpose of this study was to investigate whether liming would be a good solution to solve any future eutrophication problems in Lake Tåkern. Liming experiments were performed in mesocosms during April 2015 with a mixture of limestone and slaked lime. Quantity and diversity of plankton and water chemical variables were measured before and after liming. Moreover, samples of phytoplankton from a similar experiment conducted in July 2014 were analyzed. Liming did not show any effect on neither phyto- nor zooplankton when performed in spring of 2015. During summer of 2014, there was an increase in number of phytoplankton (ml-1 ) and chlorophyll in controls while the study showed constant levels in treated mesocosms. For zooplankton there was no significant effects of liming on neither quantity nor diversity. Results of this study suggest that liming is not the most appropriate method to resolve eutrophication in Lake Tåkern.

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