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  • 1.
    Agnvall, Beatrix
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Ali, A.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Olby, S.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology.
    Red Junglefowl (Gallus gallus) selected for low fear of humans are larger, more dominant and produce larger offspring2014In: animal, ISSN 1751-7311, Vol. 8, no 9, p. 1498-1505Article in journal (Refereed)
    Abstract [en]

    Many traits associated with domestication are suggested to have developed as correlated responses to reduced fear of humans. Tameness may have reduced the stress of living in human proximity and improved welfare in captivity. We selected Red Junglefowl (ancestors of all domestic chickens) for four generations on high or low fear towards humans, mimicking an important aspect of the earliest period of domestication, and tested birds from the third and fourth generation in three different social tests. Growth and plumage condition, as well as size of eggs and offspring were also recorded, as indicators of some aspects of welfare. Birds selected for low fear had higher weight, laid larger eggs and generated larger offspring, and had a better plumage condition. In a social dominance test they also performed more aggressive behaviour and received less of the same, regardless of whether the restricted resource was feed or not. Hence, dominance appeared to increase as a consequence of reduced fear of humans. Furthermore, egg size and the weight of the offspring were larger in the less fearful birds, and plumage condition better, which could be interpreted as the less fearful animals being better adapted to the environment in which they were selected.

  • 2.
    Agnvall, Beatrix
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Bélteky, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Brain size is reduced by selectionfor tameness in Red Junglefowl–correlated effects in vital organs2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 3306Article in journal (Refereed)
    Abstract [en]

    During domestication animals have undergone changes in size of brain and other vital organs. We hypothesize that this could be a correlated effect to increased tameness. Red Junglefowl (ancestors of domestic chickens) were selected for divergent levels of fear of humans for five generations. The parental (P0) and the fifth selected generation (S5) were culled when 48–54 weeks old and the brains were weighed before being divided into telencephalon, cerebellum, mid brain and optic lobes. Each single brain part as well as the liver, spleen, heart and testicles were also weighed. Brains of S5 birds with high fear scores (S5 high) were heavier both in absolute terms and when corrected for body weight. The relative weight of telencephalon (% of brain weight) was significantly higher in S5 high and relative weight of cerebellum was lower. Heart, liver, testes and spleen were all relatively heavier (% of body weight) in S5 high. Hence, selection for tameness has changed the size of the brain and other vital organs in this population and may have driven the domesticated phenotype as a correlated response.

  • 3.
    Agnvall, Beatrix
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Bélteky, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Katajamaa, Rebecca
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Is evolution of domestication driven by tameness? A selective review with focus on chickens2018In: Applied Animal Behaviour Science, ISSN 0168-1591, E-ISSN 1872-9045, Vol. 205, p. 227-233Article in journal (Refereed)
    Abstract [en]

    Domestication of animals offers unique possibilities to study evolutionary changes caused by similar selection pressures across a range of species. Animals from separate genera tend to develop a suite of phenotypic alterations referred to as "the domesticated phenotype". This involves changes in appearance, including loss of pigmentation, and alterations in body size and proportions. Furthermore, effects on reproduction and behaviour are typical. It is hypothesized that this recurring phenotype may be secondary effects of the increased tameness that is an inevitable first step in the domestication of any species. We first provide a general overview of observations and experiments from different species and then review in more detail a project attempting to recreate the initial domestication of chickens. Starting from an outbred population of Red Junglefowl, ancestors of all modem chickens, divergent lines were selected based on scores in a standardized fear-of-human test applied to all birds at 12 weeks of age. Up to the eighth selected generation, observations have been made on correlated effects of this selection on various phenotypes. The fear score had a significant heritability and was genetically correlated to several other behavioural traits. Furthermore, low-fear birds were larger at hatch, grew faster, laid larger eggs, had a modified metabolism and increased feed efficiency, had modified social behaviour and reduced brain size. Selection affected gene expression and DNA-methylation in the brains, but the genetic and epigenetic effects were not specifically associated with stress pathways. Further research should be focused on unraveling the genetic and epigenetic mechanisms underlying the correlated side-effects of reduced fear of humans.

  • 4.
    Agnvall, Beatrix
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Effects of Divergent Selection for Fear of Humans on Behaviour in Red Junglefowl2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 11, p. 1-12Article in journal (Refereed)
    Abstract [en]

    Domestication has caused a range of similar phenotypic changes across taxa, relating to physiology, morphology and behaviour. It has been suggested that this recurring domesticated phenotype may be a result of correlated responses to a central trait, namely increased tameness. We selected Red Junglefowl, the ancestors of domesticated chickens, during five generations for reduced fear of humans. This caused a marked and significant response in tameness, and previous studies have found correlated effects on growth, metabolism, reproduction, and some behaviour not directly selected for. Here, we report the results from a series of behavioural tests carried out on the initial parental generation (P0) and the fifth selected generation (S5), focusing on behaviour not functionally related to tameness, in order to study any correlated effects. Birds were tested for fear of humans, social reinstatement tendency, open field behaviour at two different ages, foraging/exploration, response to a simulated aerial predator attack and tonic immobility. In S5, there were no effects of selection on foraging/exploration or tonic immobility, while in the social reinstatement and open field tests there were significant interactions between selection and sex. In the aerial predator test, there were significant main effects of selection, indicating that fear of humans may represent a general wariness towards predators. In conclusion, we found only small correlated effects on behaviours not related to the tameness trait selected for, in spite of them showing high genetic correlations to fear of humans in a previous study on the same population. This suggests that species-specific behaviour is generally resilient to changes during domestication.

  • 5.
    Agnvall, Beatrix
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Jöngren, Markus
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Strandberg, Erling
    Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology. Linköping University, The Institute of Technology.
    Heritability and Genetic Correlations of Fear-Related Behaviour in Red Jungelfowl -Possible Implications for Early Domestication2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 4, p. e35162-Article in journal (Refereed)
    Abstract [en]

    Domesticated species differ from their wild ancestors in a number of traits, generally referred to as the domesticated phenotype. Reduced fear of humans is assumed to have been an early prerequisite for the successful domestication of virtually all species. We hypothesized that fear of humans is linked to other domestication related traits. For three generations, we selected Red Junglefowl (ancestors of domestic chickens) solely on the reaction in a standardized Fear of Human-test. In this, the birds were exposed for a gradually approaching human, and their behaviour was continuously scored. This generated three groups of animals, high (H), low (L) and intermediate (I) fearful birds. The birds in each generation were additionally tested in a battery of behaviour tests, measuring aspects of fearfulness, exploration, and sociality. The results demonstrate that the variation in fear response of Red Junglefowl towards humans has a significant genetic component and is genetically correlated to behavioural responses in other contexts, of which some are associated with fearfulness and others with exploration. Hence, selection of Red Junglefowl on low fear for humans can be expected to lead to a correlated change of other behavioural traits over generations. It is therefore likely that domestication may have caused an initial suite of behavioural modifications, even without selection on anything besides tameness.

  • 6.
    Agnvall, Beatrix
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Katajamaa, Rebecca
    Linköping University, Department of Physics, Chemistry and Biology, Biology.
    Altimiras, Jordi
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Is domestication driven by reduced fear of humans? Boldness, metabolism and serotonin levels in divergently selected red junglefowl (Gallus gallus)2015In: Biology Letters, ISSN 1744-9561, E-ISSN 1744-957X, Vol. 11, no 9, article id 20150509Article in journal (Refereed)
    Abstract [en]

    Domesticated animals tend to develop a coherent set of phenotypic traits. Tameness could be a central underlying factor driving this, and we therefore selected red junglefowl, ancestors of all domestic chickens, for high or low fear of humans during six generations. We measured basal metabolic rate (BMR), feed efficiency, boldness in a novel object (NO) test, corticosterone reactivity and basal serotonin levels (related to fearfulness) in birds from the fifth and sixth generation of the high- and low-fear lines, respectively (44-48 individuals). Corticosterone response to physical restraint did not differ between selection lines. However, BMR was higher in low-fear birds, as was feed efficiency. Low-fear males had higher plasma levels of serotonin and both low-fear males and females were bolder in an NO test. The results show that many aspects of the domesticated phenotype may have developed as correlated responses to reduced fear of humans, an essential trait for successful domestication.

  • 7.
    Albert, Frank W.
    et al.
    Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany, and Lewis Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America,.
    Somel, Mehmet
    Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany, CAS–MPG Partner Institute for Computational Biology SIBS, Shanghai, China.
    Carneiro, Miguel
    CIBIO, Centro de Investigac¸a˜o em Biodiversidade e Recursos Gene´ ticos, Vaira˜o, Portugal, and Departamento de Zoologia e Antropologia–Faculdade de Cieˆncias da Universidade do Porto, Porto, Po.
    Aximu-Petri, Ayinuer
    Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
    Halbwax, Michael
    Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany and Fernan Vaz Gorilla Project, Port-Gentil, Gabon.
    Thalmann, Olaf
    Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany and Department of Biology, University of Turku, Turku, Finland.
    Blanco-Aguiar, Jose A.
    CIBIO, Centro de Investigac¸a˜o em Biodiversidade e Recursos Gene´ ticos, Vaira˜o, Portugal, 5 Departamento de Zoologia e Antropologia–Faculdade de Cieˆncias da Universidade do Porto, Porto, Portugal and Instituto de Investigacio´n en Recursos Cinege´ticos, IREC (CSIC, UCLM, JCCM), Ciudad Real, Spain.
    Plyusnina, Irina Z.
    Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.
    Trut, Lyudmila
    Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.
    Villafuerte, Rafael
    Instituto de Investigacio´n en Recursos Cinege´ticos, IREC (CSIC, UCLM, JCCM), Ciudad Real, Spain.
    Ferrand, Nuno
    CIBIO, Centro de Investigac¸a˜o em Biodiversidade e Recursos Gene´ ticos, Vaira˜o, Portugal, and Departamento de Zoologia e Antropologia–Faculdade de Cieˆncias da Universidade do Porto, Porto, Portugal.
    Kaiser, Sylvia
    Department of Behavioural Biology, University of Mu¨ nster, Mu¨ nster, Germany.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology. Linköping University, The Institute of Technology.
    Pääbo, Svante
    Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
    A Comparison of Brain Gene Expression Levels in Domesticated and Wild Animals2012In: PLOS Genetics, ISSN 1553-7390, Vol. 8, no 9, p. e1002962-Article in journal (Refereed)
    Abstract [en]

    Domestication has led to similar changes in morphology and behavior in several animal species, raising the questionwhether similarities between different domestication events also exist at the molecular level. We used mRNA sequencing toanalyze genome-wide gene expression patterns in brain frontal cortex in three pairs of domesticated and wild species (dogsand wolves, pigs and wild boars, and domesticated and wild rabbits). We compared the expression differences with thosebetween domesticated guinea pigs and a distant wild relative (Cavia aperea) as well as between two lines of rats selectedfor tameness or aggression towards humans. There were few gene expression differences between domesticated and wilddogs, pigs, and rabbits (30–75 genes (less than 1%) of expressed genes were differentially expressed), while guinea pigs andC. aperea differed more strongly. Almost no overlap was found between the genes with differential expression in thedifferent domestication events. In addition, joint analyses of all domesticated and wild samples provided only suggestiveevidence for the existence of a small group of genes that changed their expression in a similar fashion in differentdomesticated species. The most extreme of these shared expression changes include up-regulation in domesticates of SOX6and PROM1, two modulators of brain development. There was almost no overlap between gene expression in domesticatedanimals and the tame and aggressive rats. However, two of the genes with the strongest expression differences betweenthe rats (DLL3 and DHDH) were located in a genomic region associated with tameness and aggression, suggesting a role ininfluencing tameness. In summary, the majority of brain gene expression changes in domesticated animals are specific tothe given domestication event, suggesting that the causative variants of behavioral domestication traits may likewise bedifferent.

  • 8.
    Anderson, Claes
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Shanmugam, Attur
    Wildlife SOS, Bannerghatta Bear Rescue Centre, Bannerghatta Biological Park, Bannerghatta, Bangalore, Karnataka, India.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Habituation to Environmental Enrichment in Captive Sloth Bears - Effect on Stereotypies2010In: Zoo Biology, ISSN 0733-3188, E-ISSN 1098-2361, Vol. 28, no 6, p. 1-10Article in journal (Refereed)
    Abstract [en]

    The benefits to captive animals of environmental enrichment (EE) are widely recognized. Few studies have, however, studied how to maximise the effect of EE. One issue with EE programs seems to be habituation to the enrichment device. To study the effect of habituation to EE, 14 captive sloth bears (Melursus ursinus) were subjected to two different EE treatments. Treatment one presented EE (logs with honey containing holes) for five consecutive days, whereas treatment two presented EE on intermittent days for five days. Intermittent presentations tended to reduce habituation toward the EE. Both consecutive and intermittent presentations significantly reduced stereotypies; however, the consecutive presentations had a longer-lasting effect. Explorative behaviors increased in both treatments, consistent with earlier findings that EE increase levels of natural behaviors. Other behaviors were unaffected by the EE presentations. The results show that intermittent presentation of EE objects may secure the interest of the animals, but continuous access to enrichment may be more efficient in reducing stereotypies in the long run.

  • 9.
    Andersson, Annelie
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Valros, Anna
    University of Helsinki, Faculty of Veterinary Medicine – Research Centre for Animal Welfare, Department of Production Animal Medicine,00014 Helsinki, Finland.
    Rombin, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Extensive infanticide in enclosed European wild boars (Sus scrofa)2011In: Applied Animal Behaviour Science, ISSN 0168-1591, E-ISSN 1872-9045, Vol. 134, no 3, p. 184-192Article in journal (Refereed)
    Abstract [en]

    Infanticidal behaviour is wide-spread among animals of various taxonomic groups, but has not previously been reported in European wild boars, which are commonly kept in enclosures in Sweden and Finland for meat and recreation purposes. We studied the behaviour of wild boars in one enclosure during three reproductive seasons. Non-maternal infanticide was documented in 14 out of 22 litters, causing the deaths of all piglets in all but one affected litters. Infanticide was typically performed during or shortly after parturition by a sow which was older and larger than the victimised sow, and we found no effect of relatedness. A questionnaire sent to 112 owners of enclosures in Sweden and Finland resulted in 62 responses. Although the owners were often not able to provide exact figures on reproduction and mortality, non-maternal infanticide was reported to be the most common cause of piglet mortality, which in total was estimated to 29.1%. The occurrence of infanticide was unrelated to size of enclosure and to variations in husbandry routines, which all together may suggest that the behaviour is part of the normal behavioural repertoire in European wild boars. The observed levels of infanticide constitute a major welfare problem in captive wild boars.

  • 10.
    Andersson, Annelie
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Äänismaa, Riikka
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Huusko, Jenni
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Behaviour of European wild boars (Sus scrofa) in connection with farrowing in an enclosure2011In: Mammalian Biology, ISSN 1616-5047, E-ISSN 1618-1476, Vol. 76, no 3, p. 332-338Article in journal (Other academic)
    Abstract [en]

    Wild boars (Sus scrofa) are often kept in enclosures for hunting or meat production purposes in Sweden. The sows are known to undergo behavioural changes in connection with farrowing and their natural behaviours may be compromised by the limited area of the enclosure. The aim of this study was to quantitatively describe wild boar sows’ behaviour when farrowing in an enclosure. A field study was carried out in a hunting enclosure, where 1200 hours of behavioural recordings and data from 22 farrowings were collected. According to the results, the farrowing period could be divided into 3 phases: pre-farrowing, isolation and sociality phases (in relation to farrowing: day -14 to -1, day 1 to 8, day 9 to 14 respectively). The activity decreased during isolation and increased in the sociality phase (p<0.05), whereas the average distance to other individuals increased during isolation and decreased in the sociality phase (p<0.05). Nose contacts with other individuals increased in the isolation phase (p<0.05) and habitat use changed towards more protective habitats after farrowing. 68 % of the nests were situated in edges between two habitats of different vegetation density and 73% had some kind of protection to the north. We conclude that farrowing induces a number of changes in the activity, social behaviour and habitat preference in captive European wild boars. This may need attention when enclosures for this species are designed.

  • 11.
    Beltéky, Johan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Eklund, Beatrix
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Gene expression of behaviorally relevant genes in the cerebral hemisphere changes after selection for tameness in Red Junglefowl.2017In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, no 5, article id e0177004Article in journal (Refereed)
    Abstract [en]

    The process of domestication in animals has led to alterations in behavior, physiology and phenotypic traits, changes that may be driven by correlations with reduced fear of humans. We used Red Junglefowl, ancestors of all domesticated chickens selected for either high or low fear of humans for five generations to study the effects of selection on gene transcription in the cerebral hemisphere, which is heavily involved in behaviour control. A total of 24 individuals from the parental generation as well as from the fifth selected generation were used. Twenty-two genes were significantly differentially expressed at p < 0.05 after false discovery rate (FDR) correction. Those genes that were upregulated in the low fearful animals were found to be involved in neural functions. Gene ontology and pathway analysis revealed enrichment for terms associated with behavioural processes. We conclude that five generations of divergent selection for high or low tameness has significantly changed gene expression patterns in the cerebral hemisphere in the Red Junglefowl population used here, which could underlie a range of changes in the domestic phenotype.

  • 12.
    Brunberg, E
    et al.
    Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Uppsala.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Isaksson, A
    Department of Medical Sciences, Uppsala University, Uppsala.
    Keeling, L
    Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Uppsala.
    Feather pecking behavior in laying hens: Hypothalamic gene expression in birds performing and receiving pecks2011In: POULTRY SCIENCE, ISSN 0032-5791, Vol. 90, no 6, p. 1145-1152Article in journal (Refereed)
    Abstract [en]

    Feather pecking (FP) is a welfare and economic problem in the egg production sector. Beak trimming, the current method used to reduce FP, is also criticized. The present study used gene expression to explore the biological mechanisms underlying this behavior, which could lead to a greater understanding of the cause and a tool to mitigate the problem. White Leghorn hens performing and receiving FP, as well as neutral control birds, were identified on a commercial farm. Hypothalamic RNA from 11 peckers, 10 victims, and 10 controls was hybridized onto GeneChip Chicken Genome Arrays (Affymetrix Inc., Santa Clara, CA) to compare gene expression profiles in the different groups. Eleven transcripts corresponding to 10 genes differed significantly between the 3 groups (adjusted P andlt; 0.05). Eight of these transcripts differed in the peckers compared with the controls, 1 was upregulated in the victims compared with the controls, and 6 differed significantly in the peckers compared with the victims. Additionally, 5 transcripts showed a trend (adjusted P andlt; 0.1) to differ in the pecker-victim comparison. Some of the products of the differently expressed genes are involved in disorders, such as intestinal inflammation and insulin resistance, which fit well with the previously proposed hypothesis that FP is an abnormal foraging behavior. Other findings may also support the proposal that FP is linked to immune mechanisms and may serve as an animal model for obsessive compulsive disorder in humans. In conclusion, this study provides a gene list that may be useful in further research on the mechanisms behind FP.

  • 13.
    Brunberg, E.
    et al.
    Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology. Linköping University, The Institute of Technology.
    Isaksson, A.
    Science for Life Laboratory, Department of Medical Sciences, Uppsala University, Uppsala, Sweden.
    Keeling, L.J.
    Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Brain gene expression differences are associated with abnormal tail biting behavior in pigs2013In: Genes, Brain and Behavior, ISSN 1601-1848, E-ISSN 1601-183X, Vol. 12, no 2, p. 275-281Article in journal (Refereed)
    Abstract [en]

    Knowledge about gene expression in animals involved inabnormal behaviors can contribute to the understandingof underlying biological mechanisms. This study aimedto explore the motivational background to tail biting,an abnormal injurious behavior and severe welfareproblem in pig production. Affymetrix microarrayswere used to investigate gene expression differencesin the hypothalamus and prefrontal cortex of pigsperforming tail biting, pigs receiving bites to the tailand neutral pigs who were not involved in the behavior.In the hypothalamus, 32 transcripts were differentiallyexpressed (P <0.05) when tail biters were comparedwith neutral pigs, 130 when comparing receiver pigswith neutrals, and two when tail biters were comparedwith receivers. In the prefrontal cortex, seven transcriptswere differently expressed in tail biters when comparedwith neutrals, seven in receivers vs. neutrals and nonein the tail biters vs. receivers. In total, 19 genesshowed a different expression pattern in neutral pigswhen compared with both performers and receivers.This implies that the functions of these may provideknowledge about why the neutral pigs are not involvedin tail biting behavior as performers or receivers.Among these 19 transcripts were genes associated withproduction traits in pigs (PDK4), sociality in humansand mice (GTF2I ) and novelty seeking in humans (EGF ).These are in line with hypotheses linking tail biting withreduced back fat thickness and explorative behavior.

  • 14.
    Brunberg, Emma I
    et al.
    NORSØK – Norwegian Centre for Organic Agriculture, Tingvoll, Norway; NIBIO – Norwegian Institute for Bioeconomy Research, Tingvoll, Norway.
    Rodenburg, T Bas
    Behavioural Ecology Group, Wageningen University, Wageningen, Netherlands.
    Rydhmer, Lotta
    Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Kjaer, Joergen B
    Federal Research Institute for Animal Health, Friedrich-Loeffler-Institut, Celle, Germany,.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Keeling, Linda J
    Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Omnivores Going Astray: A Review and New Synthesis of Abnormal Behavior in Pigs and Laying Hens2016In: Frontiers in veterinary science, ISSN 2297-1769, Vol. 3, p. 1-15, article id 57Article in journal (Refereed)
    Abstract [en]

    Pigs and poultry are by far the most omnivorous of the domesticated farm animals and it is in their nature to be highly explorative. In the barren production environments, this motivation to explore can be expressed as abnormal oral manipulation directed toward pen mates. Tail biting (TB) in pigs and feather pecking (FP) in laying hens are examples of unwanted behaviors that are detrimental to the welfare of the animals. The aim of this review is to draw these two seemingly similar abnormalities together in a common framework, in order to seek underlying mechanisms and principles. Both TB and FP are affected by the physical and social environment, but not all individuals in a group express these behaviors and individual genetic and neurobiological characteristics play an important role. By synthesizing what is known about environmental and individual influences, we suggest a novel possible mechanism, common for pigs and poultry, involving the brain-gut-microbiota axis.

  • 15.
    Brunberg, Emma
    et al.
    Swedish University of Agriculture Science, Sweden.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Isaksson, Anders
    Uppsala University, Sweden.
    Keeling, Linda J.
    Swedish University of Agriculture Science, Sweden.
    Behavioural and Brain Gene Expression Profiling in Pigs during Tail Biting Outbreaks – Evidence of a Tail Biting Resistant Phenotype2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 6Article in journal (Refereed)
    Abstract [en]

    Abnormal tail biting behaviour is a major welfare problem for pigs receiving the behaviour, as well as an indication of decreased welfare in the pigs performing it. However, not all pigs in a pen perform or receive tail biting behaviour and it has recently been shown that these ‘neutral’ pigs not only differ in their behaviour, but also in their gene expression compared to performers and receivers of tail biting in the same pen. To investigate whether this difference was linked to the cause or a consequence of them not being involved in the outbreak of tail biting, behaviour and brain gene expression was compared with ‘control’ pigs housed in pens with no tail biting. It was shown that the pigs housed in control pens performed a wider variety of pig-directed abnormal behaviour (belly nosing 0.95±1.59, tail in mouth 0.31±0.60 and ‘other‘ abnormal 1.53±4.26; mean±S.D) compared to the neutral pigs (belly nosing 0.30±0.62, tail in mouth 0.13±0.50 and “other“ abnormal 0.42±1.06). With Affymetrix gene expression arrays, 107 transcripts were identified as differently expressed (p<0.05) between these two categories of pigs. Several of these transcripts had already been shown to be differently expressed in the neutral pigs when they were compared to performers and receivers of tail biting in the same pen in an earlier study. Hence, the different expression of these genes cannot be a consequence of the neutral pigs not being involved in tail biting behaviour, but rather linked to the cause contributing to why they were not involved in tail biting interactions. These neutral pigs seem to have a genetic and behavioural profile that somehow contributes to them being resistant to performing or receiving pig-directed abnormal behaviour, such as tail biting, even when housed in an environment that elicits that behaviour in other pigs.

  • 16.
    Buller, Henry
    et al.
    Univ Exeter, England.
    Blokhuis, Harry
    Swedish Univ Agr Sci, Sweden.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Keeling, Linda
    Swedish Univ Agr Sci, Sweden.
    Towards Farm Animal Welfare and Sustainability2018In: Animals, ISSN 2076-2615, E-ISSN 2076-2615, Vol. 8, no 6, article id 81Article, review/survey (Refereed)
    Abstract [en]

    As farm animal welfare becomes an increasingly important component of contemporary global livestock production, animal welfare science and animal welfare policy-making need to find new ways of entering global debates over food security and sustainability. In this paper, we explore the means by which both animal welfare science and policy should articulate with these emerging global debates. Having first established the important gains in animal welfare policy and the maturity of animal welfare science, we identify and explore the potential impact of these current debates and argue that they have the potential for profound change in our understanding of, and our response to, the welfare of animals. We conclude the paper with a number of possible recommendations for how a scientifically informed, sustainable animal welfare policy might flourish.

  • 17.
    Bélteky, Johan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Agnvall, Beatrix
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Bektic, Lejla
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Höglund, Andrey
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Guerrero Bosagna, Carlos
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Epigenetics and early domestication: differences in hypothalamic DNA methylation between red junglefowl divergently selected for high or low fear of humans2018In: Genetics Selection Evolution, ISSN 0999-193X, E-ISSN 1297-9686, Vol. 50, article id 13Article in journal (Refereed)
    Abstract [en]

    Background: Domestication of animals leads to large phenotypic alterations within a short evolutionary time-period. Such alterations are caused by genomic variations, yet the prevalence of modified traits is higher than expected if they were caused only by classical genetics and mutations. Epigenetic mechanisms may also be important in driving domesticated phenotypes such as behavior traits. Gene expression can be modulated epigenetically by mechanisms such as DNA methylation, resulting in modifications that are not only variable and susceptible to environmental stimuli, but also sometimes transgenerationally stable. To study such mechanisms in early domestication, we used as model two selected lines of red junglefowl (ancestors of modern chickens) that were bred for either high or low fear of humans over five generations, and investigated differences in hypothalamic DNA methylation between the two populations. Results: Twenty-two 1-kb windows were differentially methylated between the two selected lines at p amp;lt; 0.05 after false discovery rate correction. The annotated functions of the genes within these windows indicated epigenetic regulation of metabolic and signaling pathways, which agrees with the changes in gene expression that were previously reported for the same tissue and animals. Conclusions: Our results show that selection for an important domestication-related behavioral trait such as tameness can cause divergent epigenetic patterns within only five generations, and that these changes could have an important role in chicken domestication.

  • 18.
    Bélteky, Johan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Agnvall, Beatrix
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Johnsson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Wright, Dominic
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Domestication and tameness: brain geneexpression in red junglefowl selected for less fear of humans suggests effects on reproduction and immunology2016In: Royal Society Open Science, E-ISSN 2054-5703, no 3, article id 160033Article in journal (Refereed)
    Abstract [en]

    The domestication of animals has generated a set of phenotypicmodifications, affecting behaviour, appearance, physiologyand reproduction, which are consistent across a range ofspecies. We hypothesized that some of these phenotypes couldhave evolved because of genetic correlation to tameness,an essential trait for successful domestication. Starting froman outbred population of red junglefowl, ancestor of alldomestic chickens, we selected birds for either high or lowfear of humans for five generations. Birds from the fifthselected generation (S5) showed a divergent pattern of growthand reproduction, where low fear chickens grew larger andproduced larger offspring. To examine underlying geneticmechanisms, we used microarrays to study gene expressionin thalamus/hypothalamus, a brain region involved in fearand stress, in both the parental generation and the S5. Whileparents of the selection lines did not show any differentiallyexpressed genes, there were a total of 33 genes with adjustedp-values below 0.1 in S5. These were mainly related to spermfunction,immunological functions, with only a few known tobe relevant to behaviour. Hence, five generations of divergentselection for fear of humans produced changes in hypothalamicgene expression profiles related to pathways associated withmale reproduction and to immunology. This may be linked to the effects seen on growth and size of offspring. These results support the hypothesis thatdomesticated phenotypes may evolve because of correlated effects related to reduced fear of humans.

  • 19.
    Campler, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Jöngren, Markus
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Fearfulness in red junglefowl and domesticated White Leghorn chickens2009In: BEHAVIOURAL PROCESSES, ISSN 0376-6357, Vol. 81, no 1, p. 39-43Article in journal (Refereed)
    Abstract [en]

    It may be hypothesised that reduced fearfulness has been a major target of selection during domestication. We tested 20 domesticated White Leghorn (WL) chickens and their ancestors, red junglefowl (RJF), in four different fear tests (Open Field, Novel Object. Aerial Predator, and Fear for Humans). The tests were designed to measure reactions to different types of potentially fearful stimuli. The correlations between durations of the same four variables from each of the tests (Stand/sit alert, Locomotion, Fly/jump, and Vocalisation) were analysed with principal components analysis (PCA). In the PCA, 33.5% of the variation in responses was explained by a single factor, interpreted as a general fear factor. Higher scores on this were related to stronger fear reactions. Red jungle fowl scored significantly higher than White Leghorns wet on this factor, and also had a longer latency to feed in the Fear of Humans-test, used as an independent measure of fear in the same tests. The results suggest that selection for low fearfulness has been an important element of domestication.

  • 20.
    Carlborg, Örjan
    et al.
    Swedish University of Agriculture Science, Uppsala.
    Kerje, Susanne
    Swedish University of Agriculture Science, Uppsala.
    Schutz, Karin
    Swedish University of Agriculture Science, Uppsala.
    Jacobsson, Lina
    Swedish University of Agriculture Science, Uppsala.
    Jensen, Per
    Swedish University of Agriculture Science, Uppsala.
    Andersson, Leif
    Swedish University of Agriculture Science, Uppsala.
    A global search reveals epistatic interaction between QTL for early growth in the chicken2003In: Genome Research, ISSN 1088-9051, E-ISSN 1549-5469, Vol. 13, no 3, p. 413-421Article in journal (Refereed)
    Abstract [en]

    We have identified quantitative trait loci (QTL) explaining a large proportion of the variation in body weights at different ages and growth between chronological ages in an F-2 intercross between red junglefowl and White Leghorn chickens. QTL were mapped using forward selection for loci with significant marginal genetic effects and with a simultaneous search for epistatic QTL pairs. We found 22 significant loci contributing to these traits, nine of these were only found by the simultaneous two-dimensional search, which demonstrates the power of this approach for detecting loci affecting complex traits. We have also estimated the relative contribution of additive, dominance, and epistasis effects to growth and the contribution of epistasis was more pronounced prior to 46 days of age, whereas additive genetic effects explained the major portion of the genetic variance later in life. Several of the detected loci affected either early or late growth but not both. Very few loci affected the entire growth process, which points out that early and late growth, at least to some extent, have different genetic regulation.

  • 21.
    Eklund, Beatrix
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Domestication effects on behavioural synchronization and individual distances in chickens ( Gallus gallus)2011In: Behavioural Processes, ISSN 0376-6357, E-ISSN 1872-8308, Vol. 86, no 2, p. 250-256Article in journal (Refereed)
    Abstract [en]

    Behavioural synchrony (allelomimetic behaviour), and inter-individual distances are aspects of social and anti-predator strategies which may have been affected by domestication. Chickens are known to adjust synchronization and inter-individual distances depending on behaviour. We hypothesized that White Leghorn (WL) chickens would show less synchronized behaviour than the ancestor, the red jungle fowl (RJF). Sixty birds, 15 female and 15 male WL and the same number of RJF (28 weeks old) were studied in groups of three in furnished pens (1 m × 2 m) for 24 consecutive hours per group, following 24 h of habituation. Video tapes covering 4 h per group (dawn, 9–10 am, 1–2 pm and dusk) were analysed. Red junglefowl perched significantly more, but there were no breed effects on the frequency or daily rhythm of any other activities, or on average inter-individual distances. Red junglefowl were more synchronized during perching and a tendency for the same was found for social behaviour. After performance of the two most synchronized behaviours, perching and comfort behaviour, individual distance increased more for RJF than WL. According to this study domestication of chickens appears not to have significantly altered the relative frequencies of different activities or average inter-individual distances, but have caused some changes in behavioural synchronization and maintenance of activity-specific inter-individual distances in chickens. The changes may indicate an adaptive response to captivity and domestication.

  • 22.
    Elfwing, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Fallahshahroudi, Amir
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Lindgren, Isa
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Altimiras, Jordi
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    The Strong Selective Sweep Candidate Gene ADRA2C Does Not Explain Domestication Related Changes In The Stress Response Of Chickens2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 8, p. e103218-Article in journal (Refereed)
    Abstract [en]

    Analysis of selective sweeps to pinpoint causative genomic regions involved in chicken domestication has revealed a strongselective sweep on chromosome 4 in layer chickens. The autoregulatory a-adrenergic receptor 2C (ADRA2C) gene is theclosest to the selective sweep and was proposed as an important gene in the domestication of layer chickens. The ADRA2Cpromoter region was also hypermethylated in comparison to the non-selected ancestor of all domesticated chicken breeds,the Red Junglefowl, further supporting its relevance. In mice the receptor is involved in the fight-or-flight response as itmodulates epinephrine release from the adrenals. To investigate the involvement of ADRA2C in chicken domestication, wemeasured gene expression in the adrenals and radiolabeled receptor ligand in three brain regions comparing the domesticWhite Leghorn strain with the wild ancestor Red Junglefowl. In adrenals ADRA2C was twofold greater expressed than therelated receptor gene ADRA2A, indicating that ADRA2C is the predominant modulator of epinephrine release but no straindifferences were measured. In hypothalamus and amygdala, regions associated with the stress response, and in striatum,receptor binding pIC50 values ranged between 8.1–8.4, and the level was not influenced by the genotyped allele. Becausechicken strains differ in morphology, physiology and behavior, differences attributed to a single gene may be lost in thenoise caused by the heterogeneous genetic background. Therefore an F10 advanced intercross strain between WhiteLeghorn and Red Junglefowl was used to investigate effects of ADRA2C alleles on fear related behaviors and fecundity. Wedid not find compelling genotype effects in open field, tonic immobility, aerial predator, associative learning or fecundity.Therefore we conclude that ADRA2C is probably not involved in the domestication of the stress response in chicken, and thestrong selective sweep is probably caused by selection of some unknown genetic element in the vicinity of the gene.

  • 23.
    Elfwing, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Lindgren, Isa
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Altimiras, Jordi
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Domestication Affected Heart Rate Regulation in Juvenile Chickens2015Manuscript (preprint) (Other academic)
    Abstract [en]

    The domestication process in chickens has involved strong selection for productive traits. There is a broad understanding of phenotypic differences between domestic breeds and their ancestor, the Red Junglefowl (RJF), on fear related behaviors, genetic architecture, physiology and productive traits. Some of these characters can potentially be explained by changes in the activity of the autonomic nervous system. To address these questions we measured heart rate as a proxy for autonomic activity in the Red Junglefowl and compared it with two domestic strains, a broiler (BRO) (meat production) and a White Leghorn strain (HY) (egg production) at two and six weeks of age. Autonomic tones were pharmacologically manipulated in broilers to assess heart rate regulation during maturation. To investigate the dynamics of  autonomic control animals were measured during baseline conditions and during acute stress.

    At two weeks of age baseline heart rate was high in all strains (RJF: 541.2±18.3, HY: 506.8±38.8, BRO: 456.0±22.3) and progressively decreased with age (RJF: 491.3±10.9, HY: 386.8±25.1, BRO:_296.8±26.9). BRO had a lower heart rate compared to RJF and HY, and the differences could not be explained by allometry alone. There was a domestication effect in BRO but not HY, which were in general more similar to RJF. These findings suggest that positive selection for somatic growth has changed heart rate regulation in broilers. During acute stress heart rate did not decrease with age in the same way than baseline values, which means that there is an increased scope for raising heart rate above baseline with age. At least in broilers the increased heart rate scope is due to a recruitment in adrenergic control in absence of a patent cholinergic tone.

  • 24.
    Elfwing, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Näsström, Åsa
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Altimiras, Jordi
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    The maturation of heart rate control in the Red Junglefowl (Gallus gallus)2015Manuscript (preprint) (Other academic)
    Abstract [en]

    Fetal development of autonomic cardiac control has been thoroughly investigated in chickens, but the maturation of the autonomic nervous system after hatching has gained little attention. At hatch the heart is under a feeble nervous control and there are indications suggesting a rapid maturation process during the first two weeks of postnatal life. We aimed to characterize the maturation by measuring heart rate at baseline and stressful conditions during the first 5 weeks of life in the Red Junglefowl and using autonomic antagonists to quantify the contribution of sympathetic and parasympathetic activity. We also compared the Red Junglefowl to the domestic broiler chickens at hatch to investigate the impact of domestication processes on heart rate regulation.

    During the first two postnatal weeks, baseline and stress heart rate progressively increased. After two weeks baseline heart rate decreased while heart rate during acute stress remained high. Adrenergic tone in Red Junglefowl increased as well early suggesting that the increase in heart rate was driven predominantly by adrenergic contributions. The adrenergic tone decreased by age after postnatal week one explaining the concomitant reduction in basal heart rate during this period. Broiler chickens possessed a strong cholinergic tone at hatch indicating that parasympathetic control has been favored perhaps due to heavy selection for somatic growth.

  • 25.
    Elfwing, Magnus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Nätt, Daniel
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Health Sciences.
    Goerlich-Jansson, Vivian C.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology. Department of Animals in Science and Society, University of Utrecht, Faculty of Veterinary Medicine, Utrecht, The Netherlands.
    Persson, Mia
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Hjelm, Jonas
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Early stress causes sex-specific, life-long changes in behaviour, levels of gonadal hormones, and gene expression in chickens2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 5, article id e0125808Article in journal (Refereed)
    Abstract [en]

    Early stress can have long-lasting phenotypic effects. Previous research shows that male and female chickens differ in many behavioural aspects, and respond differently to chronic stress. The present experiment aimed to broadly characterize long-term sex differences in responses to brief events of stress experienced during the first weeks of life. Chicks from a commercial egg-laying hybrid were exposed to stress by inducing periods of social isolation during their first three weeks of life, followed by a broad behavioural, physiological and genomic characterization throughout life. Early stressed males, but not females, where more anxious in an open field-test, stayed shorter in tonic immobility and tended to have delayed sexual maturity, as shown by a tendency for lower levels of testosterone compared to controls. While early stressed females did not differ from non-stressed in fear and sexual maturation, they were more socially dominant than controls. The differential gene expression profile in hypothalamus was significantly correlated from 28 to 213 days of age in males, but not in females. In conclusion, early stress had a more pronounced long-term effect on male than on female chickens, as evidenced by behavioral, endocrine and genomic responses. This may either be attributed to inherent sex differences due to evolutionary causes, or possibly to different stress related selection pressures on the two sexes during commercial chicken breeding.

  • 26.
    Ericsson, Maria
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Fallahsharoudi, Amir
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Bergquist, Jonas
    Uppsala University, Sweden.
    Kushnir, Mark M.
    Uppsala University, Sweden.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology. Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Domestication effects on behavioural and hormonal responses to acute stress in chickens2014In: Physiology and Behavior, ISSN 0031-9384, E-ISSN 1873-507X, Vol. 133, p. 161-169Article in journal (Refereed)
    Abstract [en]

    Comparative studies have shown that alterations in physiology, morphology and behaviour have arisen due tothe domestication. A driving factor behind many of the changes could be a shift in stress responses,withmodifiedendocrine and behavioural profiles. In the present study we compared two breeds of chicken (Gallus gallus), thedomesticWhite Leghorn (WL) egg laying breed and its ancestor, the Red Junglefowl (RJF). Birds were exposed toan acute stress event, invoked by 3 or 10 min of physical restraint. Theywere then continuouslymonitored for theeffects on a wide range of behaviours during a 60 min recovery phase. Blood samples were collected from thechicken at baseline, and after 10 and 60 min following a similar restraint stress, and the samples wereanalyzed for nine endogenous steroids of the HPA and HPG axes. Concentration of the steroids was determinedusing validated liquid chromatography tandem mass spectrometry methods. In RJF, an immediate behaviouralresponse was observed after release from restraint in several behaviours, with a relatively fast return to baselinewithin 1 h. In WL, somebehaviourswere affected for a longer period of time, and others not at all. Concentrationsof corticosterone increasedmore in RJF, but returned faster to baseline compared toWL. A range of baseline levelsfor HPG-related steroids differed between the breeds, and they were generally more affected by the stress in WLthan in RJF. In conclusion, RJF reacted stronger both behaviourally and physiologically to the restraint stress, butalso recovered faster. This would appear to be adaptive under natural conditions, whereas the stress recovery ofdomesticated birds has been altered by domestication and breeding for increased reproductive output.

  • 27.
    Ericsson, Maria
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Henriksen, Rie
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Bélteky, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Sundman, Ann-Sofie
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Shionoya, Kiseko
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Long-Term and Transgenerational Effects of Stress Experienced during Different Life Phases in Chickens (Gallus gallus)2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 4, article id e0153879Article in journal (Refereed)
    Abstract [en]

    Stress in animals causes not only immediate reactions, but may affect their biology for long periods, even across generations. Particular interest has been paid to perinatal stress, but also adolescence has been shown to be a sensitive period in mammals. So far, no systematic study has been performed of the relative importance of stress encountered during different life phases. In this study, groups of chickens were exposed to a six-day period of repeated stress during three different life phases: early (two weeks), early puberty (eight weeks) and late puberty (17 weeks), and the effects were compared to an unstressed control group. The short-term effects were assessed by behaviour, and the long-term and transgenerational effects were determined by effects on behavior and corticosterone secretion, as well as on hypothalamic gene expression. Short-term effects were strongest in the two week group and the eight week group, whereas long-term and transgenerational effects were detected in all three stress groups. However, stress at different ages affected different aspects of the biology of the chickens, and it was not possible to determine a particularly sensitive life phase. The results show that stress during puberty appears to be at least equally critical as the previously studied early life phase. These findings may have important implications for animal welfare in egg production, since laying hens are often exposed to stress during the three periods pinpointed here.

  • 28.
    Ericsson, Maria
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Domestication and ontogeny effects on the stress response inyoung chickens (Gallus gallus)2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 6_35818Article in journal (Refereed)
    Abstract [en]

    Domestication is thought to increase stress tolerance. The connection between stressor exposure,glucocorticoids and behavioural responses has been studied in adults, where domestication effectsare evident. Early stress exposure may induce detrimental effects both in short-and long term.Previous research has reported a lack of glucocorticoid response in newly hatched chickens (Gallusgallus), whereas others have found opposite results. Hence it remains unclear whether the HPA-axis isfunctional from hatch, and if domestication has affected the early post-hatch ontogeny of the stressresponse. Our aims were to investigate the early ontogeny of the HPA-axis and characterize behaviouraland hormonal stress responses in ancestral Red Junglefowl and in two domestic layer strains. Plasmacorticosteone and behavioural responses before and after physical restraint was measured on dayone, nine, 16 and 23 post hatch. The results showed significant increases of corticosterone after stressin all three breeds at all the different ages. The HPA-response decreased with age and was lower inRed Junglefowl. Behavioural responses also decreased with age, and tended to be stronger in RedJunglefowl. In summary, the HPA-axis is reactive from day one, and domestication may have affectedits development and reactivity, alongside with related behaviour responses.

  • 29.
    Eriksson, Jonas
    et al.
    Uppsala University.
    Larsson, Greger
    Uppsala University.
    Gunnarsson, Ulrika
    Uppsala University.
    Bedhom, Bertrand
    INRA AgroParisTech, France.
    Tixier-Boichard, Michele
    INRA AgroParisTech, France.
    Strömstedt, Lina
    Dep of Animal Breeding and Genetics Swedish University of Agricultural Sceinces.
    Wright, Dominic
    Uppsala University.
    Jungerius, Annemieke
    Hendrix Genetics Breeding Research Technology Centre, Netherlands.
    Vereijken, Addie
    Hendrix Genetics Breeding Research Technology Centre, Netherlands.
    Randi, Ettore
    Istituto Naxionale per la Fauna Selvatica Laboratorio di Genetica.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology. Linköping University, The Institute of Technology.
    Andersson, Leif
    Uppsala University.
    Identification of the Yellow Skin Gene Reveals a Hybrid Origin of the Domestic Chicken2008In: PLoS Genetics, ISSN 1553-7404, Vol. 4, no 2Article in journal (Refereed)
    Abstract [en]

    Yellow skin is an abundant phenotype among domestic chickens and is caused by a recessive allele (W*Y) that allows deposition of yellow carotenoids in the skin. Here we show that yellow skin is caused by one or more cis-acting and tissue-specific regulatory mutation(s) that inhibit expression of BCDO2 (beta-carotene dioxygenase 2) in skin. Our data imply that carotenoids are taken up from the circulation in both genotypes but are degraded by BCDO2 in skin from animals carrying the white skin allele (W*W). Surprisingly, our results demonstrate that yellow skin does not originate from the red junglefowl (Gallus gallus), the presumed sole wild ancestor of the domestic chicken, but most likely from the closely related grey junglefowl (Gallus sonneratii). This is the first conclusive evidence for a hybrid origin of the domestic chicken, and it has important implications for our views of the domestication process.

  • 30.
    Fallahshahroudi, Amir
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    de Kock, Neil
    Department of Chemistry, BMC, Analytical Chemistry and Neurochemistry, University of.
    Johnsson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Bektic, Lejla
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Ubhayasekera, S J Kumari A
    Department of Chemistry, BMC, Analytical Chemistry and Neurochemistry, University of.
    Bergquist, Jonas
    Department of Chemistry, BMC, Analytical Chemistry and Neurochemistry, University of.
    Wright, Dominic
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Genetic and Targeted eQTL Mapping Reveals Strong Candidate Genes Modulating the Stress Response During Chicken Domestication.2017In: G3: Genes, Genomes, Genetics, ISSN 2160-1836, E-ISSN 2160-1836, Vol. 7, no 2Article in journal (Refereed)
    Abstract [en]

    The stress response has been largely modified in all domesticated animals, offering a strong tool for genetic mapping. In chickens, ancestral Red Junglefowl react stronger both in terms of physiology and behavior to a brief restraint stress than domesticated White Leghorn, demonstrating modified functions of the hypothalamic-pituitary-adrenal (HPA) axis. We mapped quantitative trait loci (QTL) underlying variations in stress-induced hormone levels using 232 birds from the 12th generation of an advanced intercross between White Leghorn and Red Junglefowl, genotyped for 739 genetic markers. Plasma levels of corticosterone, dehydroepiandrosterone (DHEA), and pregnenolone (PREG) were measured using LC-MS/MS in all genotyped birds. Transcription levels of the candidate genes were measured in the adrenal glands or hypothalamus of 88 out of the 232 birds used for hormone assessment. Genes were targeted for expression analysis when they were located in a hormone QTL region and were differentially expressed in the pure breed birds. One genome-wide significant QTL on chromosome 5 and two suggestive QTL together explained 20% of the variance in corticosterone response. Two significant QTL for aldosterone on chromosome 2 and 5 (explaining 19% of the variance), and one QTL for DHEA on chromosome 4 (explaining 5% of the variance), were detected. Orthologous DNA regions to the significant corticosterone QTL have been previously associated with the physiological stress response in other species but, to our knowledge, the underlying gene(s) have not been identified. SERPINA10 had an expression QTL (eQTL) colocalized with the corticosterone QTL on chromosome 5 and PDE1C had an eQTL colocalized with the aldosterone QTL on chromosome 2. Furthermore, in both cases, the expression levels of the genes were correlated with the plasma levels of the hormones. Hence, both these genes are strong putative candidates for the domestication-induced modifications of the stress response in chickens. Improved understanding of the genes associated with HPA-axis reactivity can provide insights into the pathways and mechanisms causing stress-related pathologies.

  • 31.
    Fallahshahroudi, Amir
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    de Kock, Nick
    Department of Chemistry - Biomedical Center, Analytical Chemistry and Science for Life Laboratory, Uppsala University, Sweden.
    Johnsson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Ubhayasekera, S.J. Kumari A.
    Department of Chemistry - Biomedical Center, Analytical Chemistry and Science for Life Laboratory, Uppsala University, Sweden.
    Bergqvist, Jonas
    Department of Chemistry - Biomedical Center, Analytical Chemistry and Science for Life Laboratory, Uppsala University, Sweden.
    Wright, Dominic
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Domestication Effects on Stress Induced Steroid Secretion and Adrenal Gene Expression in Chickens2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, p. 1-10, article id 15345Article in journal (Refereed)
    Abstract [en]

    Understanding the genetic basis of phenotypic diversity is a challenge in contemporary biology. Domestication provides a model for unravelling aspects of the genetic basis of stress sensitivity. The ancestral Red Junglefowl (RJF) exhibits greater fear-related behaviour and a more pronounced HPA-axis reactivity than its domesticated counterpart, the White Leghorn (WL). By comparing hormones (plasmatic) and adrenal global gene transcription profiles between WL and RJF in response to an acute stress event, we investigated the molecular basis for the altered physiological stress responsiveness in domesticated chickens. Basal levels of pregnenolone and dehydroepiandrosterone as well as corticosterone response were lower in WL. Microarray analysis of gene expression in adrenal glands showed a significant breed effect in a large number of transcripts with over-representation of genes in the channel activity pathway. The expression of the best-known steroidogenesis genes were similar across the breeds used. Transcription levels of acute stress response genes such as StAR, CH25 and POMC were upregulated in response to acute stress. Dampened HPA reactivity in domesticated chickens was associated with changes in the expression of several genes that presents potentially minor regulatory effects rather than by means of change in expression of critical steroidogenic genes in the adrenal.

  • 32.
    Fallahsharoudi, Amir
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    de Kock, Neil
    Department of Chemistry e Biomedical Center, Analytical Chemistry and Neurochemistry - BMC, 75124 Uppsala, Sweden.
    Johnsson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Bektic, Lejla
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Ubhayasekera, S J Kumari A
    Department of Chemistry e Biomedical Center, Analytical Chemistry and Neurochemistry - BMC, 75124 Uppsala, Sweden.
    Bergquist, Jonas
    Department of Chemistry e Biomedical Center, Analytical Chemistry and Neurochemistry - BMC, 75124 Uppsala, Sweden.
    Wright, Dominic
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    QTL mapping of stress related gene expression in a cross between domesticated chickens and ancestral red junglefowl.2017In: Molecular and Cellular Endocrinology, ISSN 0303-7207, E-ISSN 1872-8057, Vol. 446, p. 52-58, article id S0303-7207(17)30090-4Article in journal (Refereed)
    Abstract [en]

    Domestication of animals is associated with numerous alterations in physiology, morphology, and behavior. Lower reactivity of the hypothalamic-pituitary-adrenal (HPA) axis and reduced fearfulness is seen in most studied domesticates, including chickens. Previously we have shown that the physiological stress response as well as expression levels of hundreds of genes in the hypothalamus and adrenal glands are different between domesticated White Leghorn and the progenitor of modern chickens, the Red Junglefowl. To map genetic loci associated with the transcription levels of genes involved in the physiological stress response, we conducted an eQTL analysis in the F12 generation of an inter-cross between White Leghorn and Red Junglefowl. We selected genes for further studies based on their known function in the regulation of the HPA axis or sympathoadrenal (SA) system, and measured their expression levels in the hypothalamus and the adrenal glands after a brief stress exposure (physical restraint). The expression values were treated as quantitative traits for the eQTL mapping. The plasma levels of corticosterone were also assessed. We analyzed the correlation between gene expression and corticosterone levels and mapped eQTL and their potential effects on corticosterone levels. The effects on gene transcription of a previously found QTL for corticosterone response were also investigated. The expression levels of the glucocorticoid receptor (GR) in the hypothalamus and several genes in the adrenal glands were correlated with the post-stress levels of corticosterone in plasma. We found several cis- and trans-acting eQTL for stress-related genes in both hypothalamus and adrenal. In the hypothalamus, one eQTL for c-FOS and one QTL for expression of GR were found. In the adrenal tissue, we identified eQTL for the genes NR0B1, RGS4, DBH, MAOA, GRIN1, GABRB2, GABRB3, and HSF1. None of the found eQTL were significant predictors of corticosterone levels. The previously found QTL for corticosterone was associated with GR expression in hypothalamus. Our data suggests that domestication related modification in the stress response is driven by changes in the transcription levels of several modulators of the HPA and SA systems in hypothalamus and adrenal glands and not by changes in the expression of the steroidogenic genes. The presence of eQTL for GR in hypothalamus combined with the negative correlation between GR expression and corticosterone response suggests GR as a candidate for further functional studies regarding modification of stress response during chicken domestication.

  • 33.
    Fallahsharoudi, Amir
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Løtvedt, Pia
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering. AVIAN Behavioural Genomics and Physiology Group, IFM Biology, Linköping University, 58183, Linköping, Sweden..
    Beltéky, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Altimiras, Jordi
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Changes in pituitary gene expression may underlie multiple domesticated traits in chickens.2019In: Heredity, ISSN 0018-067X, E-ISSN 1365-2540, Vol. 122, no 2, p. 195-204Article in journal (Refereed)
    Abstract [en]

    Domesticated animals share a unique set of morphological and behavioral traits, jointly referred to as the domesticated phenotype. Striking similarities amongst a range of unrelated domesticated species suggest that similar regulatory mechanisms may underlie the domesticated phenotype. These include color pattern, growth, reproduction, development and stress response. Although previous studies have focused on the brain to find mechanisms underlying domestication, the potential role of the pituitary gland as a target of domestication is highly overlooked. Here, we study gene expression in the pituitary gland of the domesticated White Leghorn chicken and its wild ancestor, the Red Junglefowl. By overlapping differentially expressed genes with a previously published list of functionally important genes in the pituitary gland, we narrowed down to 34 genes. Amongst them, expression levels of genes with inhibitory function on pigmentation (ASIP), main stimulators of metabolism and sexual maturity (TSHB and DIO2), and a potential inhibitor of broodiness (PRLR), were higher in the domesticated breed. Additionally, expression of 2 key inhibitors of the stress response (NR3C1, CRHR2) was higher in the domesticated breed. We suggest that changes in the transcription of important modulatory genes in the pituitary gland can account not only for domestication of the stress response in domestic chickens, but also for changes in pigmentation, development, and reproduction. Given the pivotal role of the pituitary gland in the regulation of multiple shared domesticated traits, we suggest that similar changes in pituitary transcriptome may contribute to the domesticated phenotype in other species as well.

  • 34.
    Favati, Anna
    et al.
    Department of Zoology, Stockholm University, Stockholm, Sweden.
    Zidar, Josefina
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Thorpe, Hanne
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Lovlie, Hanne
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    The ontogeny of personality traits in the redjunglefowl, Gallus gallus2016In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 27, no 2, p. 484-493Article in journal (Refereed)
    Abstract [en]

    Consistent behavioral differences among individuals, that is, personality, are described in numerous species. Nevertheless, thedevelopment of behavioral consistency over ontogeny remains unclear, including whether the personality of individuals is consistentthroughout life, and if adult personality can be predicted already at young age. We investigated the ontogeny of personality in thered junglefowl (Gallus gallus) by scoring personality of hatchlings at 5 time points through adulthood, including before and after themajor developmental stages of becoming independent and sexual mature. We use the conceptual framework laid out by Stamps andGroothuis (2010a) to holistically investigate the observed changes in behavioral response over ontogeny. We demonstrate that meanvalues of behavioral responses changed across ontogeny and stabilized after independence. Rank-order consistencies of behavioralresponses were overall low across independence and sexual maturation. Only in 1 case could low rank-order consistencies potentiallybe explained by different phenotypes displaying different amounts of change in behavior; more explorative individuals decreased inexploration after independence, while less explorative individuals remained so. Correlations among behavior varied across ontogenyand weakened after sexual maturation. Our results demonstrate that both absolute values and consistency of behavioral traits maychange across ontogeny and that individual developmental trajectories and adult personality only to some extent can be predictedearly in life. These results have implications for future studies on personality, highlighting that the life stage at which individuals arescored affects the observed consistency of behavioral responses.

  • 35.
    Fogelholm, Jesper
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Inkabi, Samuel
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Höglund, Andrey
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Abbey-Lee, Robin
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Johnsson, Martin
    Univ Edinburgh, Scotland; Swedish Univ Agr Sci, Sweden.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Henriksen, Rie
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Wright, Dominic
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Genetical Genomics of Tonic Immobility in the Chicken2019In: Genes, ISSN 2073-4425, E-ISSN 2073-4425, Vol. 10, no 5, article id 341Article in journal (Refereed)
    Abstract [en]

    Identifying the molecular mechanisms of animal behaviour is an enduring goal for researchers. Gaining insight into these mechanisms enables us to gain a greater understanding of behaviour and their genetic control. In this paper, we perform Quantitative Trait Loci (QTL) mapping of tonic immobility behaviour in an advanced intercross line between wild and domestic chickens. Genes located within the QTL interval were further investigated using global expression QTL (eQTL) mapping from hypothalamus tissue, as well as causality analysis. This identified five candidate genes, with the genes PRDX4 and ACOT9 emerging as the best supported candidates. In addition, we also investigated the connection between tonic immobility, meat pH and struggling behaviour, as the two candidate genes PRDX4 and ACOT9 have previously been implicated in controlling muscle pH at slaughter. We did not find any phenotypic correlations between tonic immobility, struggling behaviour and muscle pH in a smaller additional cohort, despite these behaviours being repeatable within-test.

  • 36.
    Foyer, Pernilla
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology. Swedish National Defence College, Stockholm, Sweden.
    Bjällerhag, Nathalie
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Wilsson, Erik
    Swedish Armed Forces Dog Instruct Centre, Sweden .
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Behaviour and experiences of dogs during the first year of life predict the outcome in a later temperament test2014In: Applied Animal Behaviour Science, ISSN 0168-1591, E-ISSN 1872-9045, Vol. 155, p. 93-100Article in journal (Refereed)
    Abstract [en]

    Early life experiences are known to shape the behavioural development of animals, and therefore events occurring during preadolescence and adolescence may have long-term effects. In dogs, this period of time may be important for later behaviour and thereby also the suitability of dogs for different working tasks. We used the breeding practice for Swedish military working dogs to investigate this possibility. German Shepherds were bred at a central facility and then kept in host families for about a year, before participating in a standardised test determining their temperament, behaviour, and suitability for further training. We surveyed the link between the behaviour of 71 prospective military working dogs in their home situations during the first year of life as assessed by an amended C-BARQ survey, and their performance in a temperament test (T-test) applied at about 17 months of age. Dogs which scored high for C-BARQ category "Trainability" showed a significantly higher success rate in the T-test (P less than 0.001), while dogs that scored high for "Stranger-directed fear", "Non-social fear" and "Dog-directed fear" showed a significantly lower success rate (all P less than 0.05). Also dogs with higher C-BARQ scores on "Hyperactivity/restlessness, difficulties in settling down" (P=0.028), and "Chasing/following shadows or light spots" (P=0.035) were more successful, as were dogs left longer times at home (2.97 +/- 0.32 vs. 2.04 +/- 0.33 h/day; P=0.050). Index value, describing the expected success rate in the T-test, was negatively correlated with "Non-social fear" (r = -0.35) and "Stranger directed fear" (r = -0.35). The combined effect of the significant C-BARQ categories explained 29.5% of the variance in the later T-test results (P=0.006). The results indicate that the experiences and behaviour of the dogs during their first year of life is crucial in determining their later behaviour and temperament, something that could potentially be used to improve selection procedures for working dogs. Furthermore, an unsuspected result was that success in the T-test was correlated with behaviours usually associated with problem behaviour, which calls for a deeper analysis of the selection criteria used for working dogs.

  • 37.
    Foyer, Pernilla
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering. Department of Military Studies, Military-Technology Division, Swedish Defence University, Stockholm, Sweden.
    Svedberg, Anna-Maria
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Nilsson, Emma
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Wilsson, Erik
    Swedish Armed Forces Dog Training Unit, Märsta, Sweden.
    Olsen Faresjö, Åshild
    Linköping University, Department of Medical and Health Sciences, Division of Community Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Behavior and cortisol responses of dogs evaluated in a standardized temperament test for military working dogs2016In: Journal of Veterinary Behavior: Clinical Applications and Research, ISSN 1558-7878, E-ISSN 1878-7517, Vol. 11, p. 7-12Article in journal (Refereed)
    Abstract [en]

    Military and police working dogs are often exposed to stressful or threatening events, and an improper response, e.g., fear, may implicate both reduced working efficiency and welfare. Therefore, identifying individuals that display a favorable response to potentially threatening situations is of great interest. In the present study, we investigated behavior responses of 85 prospective military working dogs in 4 subtests in a standardized temperament test used to select working dogs for the Swedish Armed Forces. Our goal was to evaluate behavioral responses in specific subtests and cortisol responses of candidate dogs. After dogs were rated as approved or nonapproved based on the test leader’s assessment of the full test result, we independently analyzed video recordings of 4 subtests. In addition, for 37 dogs, we analyzed pretest and posttest salivary cortisol levels. Dogs which were approved by the test leader for further training scored higher in the video recordings on emotionality and, in particular, fear-related behavior during a subset of the test and had higher levels of cortisol both before and after the test, than nonapproved dogs. Although this may actually reflect the desired traits, it could also indicate a bias in the selection procedure, which may pose limitations on the attempts to recruit the most suitable working dogs.

  • 38.
    Foyer, Pernilla
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology. Swedish National Defence College, Stockholm, Sweden.
    Wilsson, Erik
    Swedish Armed Forces Dog Instruction Centre, Märsta, Sweden.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Levels of maternal care in dogs affect adult off spring temperament2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6Article in journal (Refereed)
    Abstract [en]

    Dog puppies are born in a state of large neural immaturity; therefore, the nervous system is sensitive to environmental influences early in life. Early experiences, such as maternal care, have been shown to have a profound and lasting effect on the future behaviour and physiology of offspring in rodents and primates. We hypothesised that this would also be the case for dogs with important implications for the breeding of working dogs. In the present study, variation in the mother--‐offspring interactions of German Shepherd dogs within the Swedish breeding program for military working dogs was studied by video recording 22 mothers with their litters during the first three weeks postpartum. The aim was to classify mothers with respect to their level of maternal care and to investigate the effect of this care on pup behaviour in a standardised temperament test carried out at approximately 18 months of age. The results show that females differed consistently in their level of maternal care, which significantly affected the adult behaviour of the offspring, mainly with respect to behaviours classified as Physical and Social Engagement, as well as Aggression. Taking maternal quality into account in breeding programs may therefore improve the process of selecting working dogs.

  • 39.
    Foyer, Pernilla
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology. Swedish National Defence College, Stockholm, Sweden.
    Wilsson, Erik
    Swedish Armed Forces Dog Instruction Centre, Märsta, Sweden.
    Wright, Dominic
    Linköping University, Department of Physics, Chemistry and Biology, Zoology. Linköping University, The Institute of Technology.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology. Linköping University, The Institute of Technology.
    Early experiences modulate stress coping in a population of German shepherd dogs2013In: Applied Animal Behaviour Science, ISSN 0168-1591, E-ISSN 1872-9045, Vol. 146, no 1-4, p. 79-87Article in journal (Refereed)
    Abstract [en]

    Early experiences may alter later behavioural expressions in animals and these differences can be consistent through adulthood. In dogs, this may have a profound impact on welfare and working ability and, it is therefore interesting to evaluate how experiences during the first weeks of life contribute to shaping the long-term behaviour. We analysed data from 503 dogs from 105 litters, bred at the Swedish Armed Forces Dog Kennel. For each dog, the data comprised information on dam and sire, sex, litter size, sex ratio of litter, date of birth, and weight at birth, and at 10 days of age. Between the ages of 377 and 593 days, the dogs were tested in a temperament test, assessing their suitability as working dogs. The behaviour test comprised 12 different sub-tests, and was scored on a behavioural rating scale. A principal component analysis showed that the test performance could largely be attributed to four principal components (explaining 55.7% of variation), labelled Confidence, Physical Engagement, Social Engagement and Aggression. We analysed the effects of the different early life variables and sex on the principal component scores (PC scores) using linear modelling. PC scores on Confidence were affected by parity, sex and litter size, and Physical Engagement was affected by parity, growth rate, litter size and season of birth. Social Engagement was affected by growth rate and sex, and Aggression was affected by sex. Some of these effects disappeared when they were combined into a single linear model, but most of them remained significant also when controlling for collinearity. The results suggest that the early environment of dogs have long-lasting effects on their behaviour and coping styles in a stressful test situation and this knowledge can be used in the work with breeding of future military or police working dogs.

  • 40.
    Goerlich, Vivian C.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Zoology. Linköping University, The Institute of Technology.
    Nätt, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Zoology. Linköping University, The Institute of Technology.
    Elfwing, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Zoology. Linköping University, The Institute of Technology.
    Macdonald, Barry
    Linköping University, Department of Physics, Chemistry and Biology, Zoology. Linköping University, The Institute of Technology.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology. Linköping University, The Institute of Technology.
    Transgenerational effects of early experience on acute stress reactions in behaviour, steroid hormones and gene expression in the precocial chicken2012In: Hormones and Behavior, ISSN 0018-506X, E-ISSN 1095-6867, Vol. 61, no 5, p. 711-718Article in journal (Refereed)
    Abstract [en]

    Stress during early life can profoundly influence an individual’s phenotype. Effects can manifest in the short-term as well as later in life and even in subsequent generations. Transgenerational effects of stress are potentially mediated via modulation of the hypothalamic-pituitary-adrenal axis (HPA) as well as epigenetic mechanisms causing heritable changes in gene expression. To investigate these pathways we subjected domestic chicks (Gallus gallus) to intermittent social isolation, food restriction, and temperature stress for the first three weeks of life. The early life stress resulted in a dampened corticosterone response to restraint stress in the parents and male offspring. Stress-specific genes, such as early growth response 1 (EGR1) and corticotropin releasing hormone receptor 1 (CRHR1), were upregulated when chicks were tested in the context of restraint stress, but not under baseline conditions. Treatment differences in gene expression were also correlated across generations which indicate transgenerational epigenetic inheritance, possibly mediated by differences in maternal yolk estradiol and testosterone. In an associative learning test early stressed birds made more correct choices suggesting a higher coping ability in stressful situations. This study is the first to show transgenerational effects of early life stress in a precocial species by combining behavioural, endocrinological, and transcriptomic measurements.

  • 41.
    Guerrero-Bosagna, Carlos
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology.
    Globalization, climate change, and transgenerational epigenetic inheritance: will our descendants be at risk?2015In: Clinical Epigenetics, E-ISSN 1868-7083, Vol. 7, no 8Article in journal (Refereed)
    Abstract [en]

    Transgenerational epigenetic inheritance has gained increased attention due to the possibility that exposure to environmental contaminants induce diseases that propagate  across generations through epigenomic alterations in gametes. In laboratory animals,exposure to environmental toxicants such as fungicides, pesticides, or plastic compounds has been shown to produce abnormal reproductive or metabolic phenotypes that are transgenerationally transmitted. Human exposures to environmental toxicants have increased due to industrialization and globalization, as well as the incidence of diseases shown to be transgenerationally transmitted in animal models. This new knowledge poses an urgent call to study transgenerational  consequences of current human exposures to environmental toxicants.

  • 42.
    Guerrero-Bosagna, Carlos
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Optimized method for methylated DNA immuno-precipitation2015In: MethodsX, ISSN 1258-780X, E-ISSN 2215-0161, Vol. 2, p. e432-e439, article id eArticle in journal (Refereed)
    Abstract [en]

    Methylated DNA immunoprecipitation (MeDIP) is one of the most widely used methods to evaluate DNA methylation on a whole genome scale, and involves the capture of the methylated fraction of the DNA by an antibody specific to methyl-cytosine. MeDIP was initially coupled with microarray hybridization to detect local DNA methylation enrichments along the genome. More recently, MeDIP has been coupled with next generation sequencing, which highlights its current and future applicability. In previous studies in which MeDIP was applied, the protocol took around 3 days to be performed. Given the importance of MeDIP for studies involving DNA methylation, it was important to optimize the method in order to deliver faster turnouts. The present article describes optimization steps of the MeDIP method. The length of the procedure was reduced in half without compromising the quality of the results. This was achieved by:

    • Reduction of the number of washes in different stages of the protocol, after a careful evaluation of the number of indispensable washes.

    • Reduction of reaction times for detaching methylated DNA fragments from the complex agarose beads:antibody.

    • Modification of the methods to purify methylated DNA, which incorporates new devices and procedures, and eliminates a lengthy phenol and chloroform:isoamyl alcohol extraction.

  • 43.
    Gunnarsson, Ulrika
    et al.
    Department of Medical Biochemistry and Microbiology Uppsala University.
    Hellström, Anders R.
    Department of Medical Biochemistry and Microbiology Uppsala university.
    Tixier-Boichard, Michele
    UMR Ge´ne´tique et DiversiteUMR Ge´ne´tique et Diversit INRA, France.
    Minvielle, Francis
    UMR Ge´ne´tique et Diversite Animales INRA, France.
    Bed¿hom, Bertrand
    ¿UMR Ge´ne´tique et Diversite´ Animales INRA, France.
    Ito, Shin¿ichi
    Faculty of Applied Biological Sciences Gifu university, Japan.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Rattink, Annemieke
    Euribrid Breeding Research Centre Nutreco, The Netherlands.
    Vereijken, Addie
    Euribrid Breeding Research Centre Nutreco, The Netherlands.
    Andersson, Leif
    Department of Medical Biochemistry and Microbiology Uppsala university.
    Mutations in SLC45A2 Cause Plumage Color Variation in Chicken and Japanese Quail2007In: Genetics, ISSN 0016-6731, E-ISSN 1943-2631, Vol. 175, p. 867-877Article in journal (Refereed)
  • 44.
    Hedlund, Louise
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Whittle, Rosemary
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Effects of commercial hatchery processing on short- and long-term stress responses in laying hens2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 2367Article in journal (Refereed)
    Abstract [en]

    In commercial egg production, chicks are exposed to a potentially stressful procedure during their first day of life. Here, we investigated how this procedure affects the chickens in a short-as well as long-term perspective by conducting two behaviour tests and measuring corticosterone (CORT) and sex hormone levels at different time points. These results were compared with a group of control chickens from the same hatchery and incubator that did not go through the commercial hatchery routine. Chickens were continuously weighed, egg production data was collected and feather scoring was performed. We found that chicks have a significant increase in CORT during the hatchery process, which implies they are exposed to stress. During first weeks of life, these chicks were more fearful, had a higher CORT reactivity during restraint and weighed more than control chicks. Later in life, hatchery treated chickens had more feather damages and injuries on combs and wattles, a faster onset of egg laying and higher levels of estradiol. We conclude that processing at the commercial hatchery was a stressful event with short-and long-term effects on behaviour and stress reactivity, and potentially also positive effects on production. The results are relevant for a large number of individuals, since the chicken is by far the globally most common farm animal.

  • 45.
    Hellstrom, Anders R
    et al.
    Uppsala University.
    Sundstrom, Elisabeth
    Swedish University Agriculture Science.
    Gunnarsson, Ulrika
    Uppsala University.
    BedHom, Bertrand
    AgroParisTech.
    Tixier-Boichard, Michele
    AgroParisTech.
    Honaker, Christa F
    Virginia Polytech Institute and State University.
    Sahlqvist, Anna-Stina
    Uppsala University.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Siegel, Paul B
    Virginia Polytech Institute and State University.
    Kerje, Susanne
    Uppsala University.
    Andersson, Leif
    Uppsala University.
    Sex-linked barring in chickens is controlled by the CDKN2A/B tumour suppressor locus2010In: PIGMENT CELL and MELANOMA RESEARCH, ISSN 1755-1471, Vol. 23, no 4, p. 521-530Article in journal (Refereed)
    Abstract [en]

    Sex-linked barring, a common plumage colour found in chickens, is characterized by black and white barred feathers. Previous studies have indicated that the white bands are caused by an absence of melanocytes in the feather follicle during the growth of this region. Here, we show that Sex-linked barring is controlled by the CDKN2A/B locus, which encodes the INK4b and ARF transcripts. We identified two non-coding mutations in CDKN2A that showed near complete association with the phenotype. In addition, two missense mutations were identified at highly conserved sites, V9D and R10C, and every bird tested with a confirmed Sex-linked barring phenotype carried one of these missense mutations. Further work is required to determine if one of these or a combined effect of two or more CDKN2A mutations is causing Sex-linked barring. This novel finding provides the first evidence that the tumour suppressor locus CDKN2A/B can affect pigmentation phenotypes and sheds new light on the functional significance of this gene.

  • 46.
    Henriksen, Rie
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Johnsson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Andersson, L
    Department of Medical Biochemistry and Microbiology, Uppsala University, Sweden.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Wright, Dominic
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    The domesticated brain: genetics of brain mass and brain structure in an avian species.2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6Article in journal (Refereed)
    Abstract [en]

    As brain size usually increases with body size it has been assumed that the two are tightly constrained and evolutionary studies have therefore often been based on relative brain size (i.e. brain size proportional to body size) rather than absolute brain size. The process of domestication offers an excellent opportunity to disentangle the linkage between body and brain mass due to the extreme selection for increased body mass that has occurred. By breeding an intercross between domestic chicken and their wild progenitor, we address this relationship by simultaneously mapping the genes that control inter-population variation in brain mass and body mass. Loci controlling variation in brain mass and body mass have separate genetic architectures and are therefore not directly constrained. Genetic mapping of brain regions indicates that domestication has led to a larger body mass and to a lesser extent a larger absolute brain mass in chickens, mainly due to enlargement of the cerebellum. Domestication has traditionally been linked to brain mass regression, based on measurements of relative brain mass, which confounds the large body mass augmentation due to domestication. Our results refute this concept in the chicken.

  • 47.
    Håkansson, Jennie
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Ahlander, Susanne
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Behavioural sex differences and diurnal crowing rhythms in red junglefowl (Gallus gallus) in Northern India2010Article in journal (Refereed)
  • 48.
    Håkansson, Jennie
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Bratt, Carl
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Behavioural differences between two captive populations of red junglefowl (Gallus gallus) with different genetic background, raised under identical conditions2007In: Applied Animal Behaviour Science, ISSN 0168-1591, E-ISSN 1872-9045, Vol. 102, no 1-2, p. 24-38Article in journal (Refereed)
    Abstract [en]

    Ex situ conservation of threatened species may lead to behavioural adaptation, which can affect success of reintroduction attempts. In previous studies, we investigated the effects of captivity on the behaviour of red jungle fowl (Gallus gallus) and found that captive populations differed behaviourally as well as genetically. The aim of the present study was to compare the behaviour of two of the previously studied populations, raised under identical conditions. Eggs were collected from birds at Copenhagen zoo (Cop) and Götala research station (Got) and were incubated and hatched together. Twenty-eight birds (16 Got and 12 Cop) were reared together and tested in eight different behavioural tests, measuring different aspects of fear-related behaviours as well as exploratory and social behaviours. The study revealed several differences in fear-related behaviours between the populations but none in exploratory or social behaviours. In general, one of the populations (Cop) showed more intense fear behaviours than the other (Got), which instead were less fearful in their behaviours. This indicates that breeding animals in captivity may lead to behavioural modifications, which can affect the outcome of reintroductions. The results further suggest that fear-related behaviours are dependent on the genetic background of the animals while social behaviours may be more influenced by the social environment. Since fear-related behaviours, such as predator avoidance and fear of humans, are essential for a life in the wild, these aspects are crucial for the breeding of animals in captivity for conservation purposes.

  • 49.
    Håkansson, Jennie
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    A longitudinal study of antipredator behaviour in four successive generations of two populations of captive red junglefowl2008In: Applied Animal Behaviour Science, ISSN 0168-1591, E-ISSN 1872-9045, Vol. 114, no 3-4, p. 409-418Article in journal (Refereed)
    Abstract [en]

    Conservation breeding and reintroduction into the wild can only be an effective management tool if behaviours essential for a life in the wild are maintained in captivity. The aim of this study was to investigate how a protected captive environment influences antipredator behaviour over generations. The red junglefowl (Gallus gallus) was used as a case study. Birds from two different captive populations were followed over four generations. In the last three generations, all birds were hatched and reared in the same indoor settings. Antipredator behaviour was measured in each generation in a standardised test where the birds were exposed to a simulated predator attack. The test was divided into three parts: pre-exposure period, exposure and post-exposure periods. There was an interaction effect between Population and generation (F-3.129 = 4.84, P < 0.01) on behaviour during the pre-exposure period, suggesting that the birds "baseline" agitation level may have been altered differently in the two populations. Population differences were also found during the post-exposure period but the populations tended to become more similar over successive generations in their behaviour after the exposure. Furthermore, there were significant effects of generation (H (d.f. = 1, N = 137) = 10.94, P < 0.05) as well as population (H (d.f. = 1, N = 137) = 5.17, P < 0.05) on the immediate reaction to the simulated predator attack. In conclusion, over four successive generations, the two populations altered their antipredator behaviour and tended to become more similar. This study shows that antipredator behaviour may change over generations in a captive environment. This is likely to be one of the most crucial factors for successful reintroduction into the wild and hence, it is a very important aspect to consider for conservation breeding.

  • 50.
    Håkansson, Jennie
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Jensen, Per
    Linköping University, Department of Physics, Chemistry and Biology, Zoology . Linköping University, The Institute of Technology.
    Behavioural and morphological variation between captive populations of red junglefowl (Gallus gallus) - possible implications for conservation2005In: Biological Conservation, ISSN 0006-3207, Vol. 122, no 3, p. 431-439Article in journal (Refereed)
    Abstract [en]

    The escalating threats to ecosystems worldwide have lead to a need for efficient methods to breed animals in captivity and to prepare captive-born animals for release back to the wild. However, life in captivity may lead to modifications in the animal’s behaviour mainly by genetic changes, including behavioural adaptations such as reduced predator responses. Such modifications may seriously affect survival after a reintroduction. The present study was a first screening of behavioural and morphological variation between different captive populations in standardized test situations using red junglefowl as a model species. The birds were tested in three different test situations in order to measure anti-predatory behaviour, social behaviour and exploratory behaviour. The results of this study clearly show that there are behavioural differences between the captive populations which potentially can be crucial for the animals in a reintroduction situation. However, the extent to which these differences are due to genetic changes caused by small breeding populations or adaptations to the different captive environments is not yet known, although morphological differences found suggest that genetic variation may cause some of the behavioural differences as well. The differences found imply that life in captivity can affect an animal’s behaviour and even though the red junglefowl is merely used as a model here, this suggests that these aspects may be important to consider also in other species where reintroduction is a more central motive for keeping the animals in captivity.

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