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  • 1.
    Agnvall, Beatrix
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Early domestication?: Phenotypic alterations of Red Junglefowl selected for divergent fear of humans2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Domestication is the process through which animals adapt to conditions provided by humans. The domesticated phenotype differs from wild ancestors in a number of traits relating to physiology, morphology and behaviour. One of the most striking differences is the animals’ fear response towards humans, and reduced fear of humans is assumed to have been an early prerequisite for the success of domestication. The early alterations seen in the domesticated phenotype may be traits developed as a correlated selection response due to tameness rather than selected upon one by one.

    This thesis summarizes a project where Red Junglefowl were selected for divergent fear of humans during six generations. In every generation, fear response to human was assessed in a standardized test and, according to fear score, the animals were bred for either high fear of humans (H) or low fear of humans (L). The animals were, above that of the standardized selection test, behaviourally phenotyped in different tests in each generation mainly focusing on fear, exploration and social behaviour. In addition to behaviour, the animals were phenotyped for body weight, egg weight, metabolism, feed intake, plumage condition, blood plasma corticosterone and peripheral serotonin. After culling, vital organs and brains were harvested and weighed.

    In paper I, we demonstrated that the selection trait has a significant genetic heritability and is genetically correlated with other behavioural responses associated with fearfulness and exploration. In paper II, we concluded that animals from the L strain had better plumage condition, higher weight, laid larger eggs and also generated larger offspring. Furthermore, when tested in a social dominance test with a limited resource, they received less and performed more aggression regardless of whether the restricted source was edible or not. In paper III, we revealed that animals from the L strain had higher basal metabolic rate as chicks, gained more weight in relation to feed intake and were bolder in a Novel Object test. Furthermore, the L males had higher plasma levels of peripheral serotonin, but the corticosterone after a restraint stress test did not differ. In paper IV and V, we concluded the project by comparing brain and organ weights as well as behaviour of the parental generation (P0) with the fifth selected generation (S5). The absolute brain weight as well as the weight specific brain weight were larger in the animals selected on H than in the L-animals. The relative weight of telencephalon was significantly higher in H whereas relative weight of cerebellum was significantly lower. Heart, liver, spleen and testes were all relatively heavier in H animals than in L. Interestingly, the behaviours assessed in P0 and S5 seemed to be rather resilient to the selection with only small differences in S5.

    To summarize, the selection on divergent tameness in Red Junglefowl has affected several phenotypic traits associated with the domesticated phenotype. The results of this project indicate that tameness in Red Junglefowl could be an underlying factor driving trait modifications towards the domesticated phenotype.

    Delarbeid
    1. Heritability and Genetic Correlations of Fear-Related Behaviour in Red Jungelfowl -Possible Implications for Early Domestication
    Åpne denne publikasjonen i ny fane eller vindu >>Heritability and Genetic Correlations of Fear-Related Behaviour in Red Jungelfowl -Possible Implications for Early Domestication
    2012 (engelsk)Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, nr 4, s. e35162-Artikkel i tidsskrift (Fagfellevurdert) Published
    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.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-76833 (URN)10.1371/journal.pone.0035162 (DOI)000305336200026 ()
    Tilgjengelig fra: 2012-04-20 Laget: 2012-04-20 Sist oppdatert: 2017-12-07
    2. Red Junglefowl (Gallus gallus) selected for low fear of humans are larger, more dominant and produce larger offspring
    Åpne denne publikasjonen i ny fane eller vindu >>Red Junglefowl (Gallus gallus) selected for low fear of humans are larger, more dominant and produce larger offspring
    2014 (engelsk)Inngår i: animal, ISSN 1751-7311, Vol. 8, nr 9, s. 1498-1505Artikkel i tidsskrift (Fagfellevurdert) Published
    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.

    sted, utgiver, år, opplag, sider
    Cambridge University Press, 2014
    Emneord
    Red Junglefowl, domestication, fearfulness, selection, social behaviour
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-109499 (URN)10.1017/S1751731114001426 (DOI)000342219000013 ()24910136 (PubMedID)
    Tilgjengelig fra: 2014-08-20 Laget: 2014-08-20 Sist oppdatert: 2016-11-17
    3. Is domestication driven by reduced fear of humans? Boldness, metabolism and serotonin levels in divergently selected red junglefowl (Gallus gallus)
    Åpne denne publikasjonen i ny fane eller vindu >>Is domestication driven by reduced fear of humans? Boldness, metabolism and serotonin levels in divergently selected red junglefowl (Gallus gallus)
    2015 (engelsk)Inngår i: Biology Letters, ISSN 1744-9561, E-ISSN 1744-957X, Vol. 11, nr 9, artikkel-id 20150509Artikkel i tidsskrift (Fagfellevurdert) Published
    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.

    sted, utgiver, år, opplag, sider
    ROYAL SOC, 2015
    Emneord
    genetics; domestication; stress
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-123162 (URN)10.1098/rsbl.2015.0509 (DOI)000364772300009 ()26382075 (PubMedID)
    Merknad

    Funding Agencies|research council Formas; ERC [322206]

    Tilgjengelig fra: 2015-12-07 Laget: 2015-12-04 Sist oppdatert: 2019-10-07bibliografisk kontrollert
    4. Effects of Divergent Selection for Fear of Humans on Behaviour in Red Junglefowl
    Åpne denne publikasjonen i ny fane eller vindu >>Effects of Divergent Selection for Fear of Humans on Behaviour in Red Junglefowl
    2016 (engelsk)Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, nr 11, s. 1-12Artikkel i tidsskrift (Fagfellevurdert) Published
    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.

    sted, utgiver, år, opplag, sider
    PLOS, 2016
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-132742 (URN)10.1371/journal.pone.0166075 (DOI)000387909300035 ()27851792 (PubMedID)
    Merknad

    European Research Council [322206]; FORMAS [221-2007-838]; Vetenskapsradet [621-2008-5437]

    Tilgjengelig fra: 2016-11-22 Laget: 2016-11-22 Sist oppdatert: 2017-11-29bibliografisk kontrollert
  • 2.
    Agnvall, Beatrix
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Ali, A.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Olby, S.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Jensen, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Red Junglefowl (Gallus gallus) selected for low fear of humans are larger, more dominant and produce larger offspring2014Inngår i: animal, ISSN 1751-7311, Vol. 8, nr 9, s. 1498-1505Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 3.
    Agnvall, Beatrix
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Bélteky, Johan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Jensen, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Brain size is reduced by selectionfor tameness in Red Junglefowl–correlated effects in vital organs2017Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikkel-id 3306Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 4.
    Agnvall, Beatrix
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Bélteky, Johan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Katajamaa, Rebecca
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Jensen, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Is evolution of domestication driven by tameness? A selective review with focus on chickens2018Inngår i: Applied Animal Behaviour Science, ISSN 0168-1591, E-ISSN 1872-9045, Vol. 205, s. 227-233Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 5.
    Agnvall, Beatrix
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Jensen, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Effects of Divergent Selection for Fear of Humans on Behaviour in Red Junglefowl2016Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, nr 11, s. 1-12Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 6.
    Agnvall, Beatrix
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Jöngren, Markus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Strandberg, Erling
    Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Jensen, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Zoologi. Linköpings universitet, Tekniska högskolan.
    Heritability and Genetic Correlations of Fear-Related Behaviour in Red Jungelfowl -Possible Implications for Early Domestication2012Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, nr 4, s. e35162-Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 7.
    Agnvall, Beatrix
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Katajamaa, Rebecca
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Altimiras, Jordi
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Jensen, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Is domestication driven by reduced fear of humans? Boldness, metabolism and serotonin levels in divergently selected red junglefowl (Gallus gallus)2015Inngår i: Biology Letters, ISSN 1744-9561, E-ISSN 1744-957X, Vol. 11, nr 9, artikkel-id 20150509Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 8.
    Beltéky, Johan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Eklund, Beatrix
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Jensen, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Gene expression of behaviorally relevant genes in the cerebral hemisphere changes after selection for tameness in Red Junglefowl.2017Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, nr 5, artikkel-id e0177004Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 9.
    Bélteky, Johan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Agnvall, Beatrix
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Bektic, Lejla
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Höglund, Andrey
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Jensen, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Guerrero Bosagna, Carlos
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Epigenetics and early domestication: differences in hypothalamic DNA methylation between red junglefowl divergently selected for high or low fear of humans2018Inngår i: Genetics Selection Evolution, ISSN 0999-193X, E-ISSN 1297-9686, Vol. 50, artikkel-id 13Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 10.
    Bélteky, Johan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Agnvall, Beatrix
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Johnsson, Martin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Wright, Dominic
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Jensen, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Domestication and tameness: brain geneexpression in red junglefowl selected for less fear of humans suggests effects on reproduction and immunology2016Inngår i: Royal Society Open Science, E-ISSN 2054-5703, nr 3, artikkel-id 160033Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 11.
    Eklund, Beatrix
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Zoologi. Linköpings universitet, Tekniska högskolan.
    Jensen, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Zoologi. Linköpings universitet, Tekniska högskolan.
    Domestication effects on behavioural synchronization and individual distances in chickens ( Gallus gallus)2011Inngår i: Behavioural Processes, ISSN 0376-6357, E-ISSN 1872-8308, Vol. 86, nr 2, s. 250-256Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 12.
    Nätt, Daniel
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Agnvall, Beatrix
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Jensen, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Zoologi. Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Large Sex Differences in Chicken Behavior and Brain Gene Expression Coincide with Few Differences in Promoter DNA-Methylation2014Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, nr 4, s. e96376-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    While behavioral sex differences have repeatedly been reported across taxa, the underlying epigenetic mechanisms in thebrain are mostly lacking. Birds have previously shown to have only limited dosage compensation, leading to high sex bias ofZ-chromosome gene expression. In chickens, a male hyper-methylated region (MHM) on the Z-chromosome has beenassociated with a local type of dosage compensation, but a more detailed characterization of the avian methylome islimiting our interpretations. Here we report an analysis of genome wide sex differences in promoter DNA-methylation andgene expression in the brain of three weeks old chickens, and associated sex differences in behavior of Red Junglefowl(ancestor of domestic chickens). Combining DNA-methylation tiling arrays with gene expression microarrays we show that aspecific locus of the MHM region, together with the promoter for the zinc finger RNA binding protein (ZFR) gene onchromosome 1, is strongly associated with sex dimorphism in gene expression. Except for this, we found few differences inpromoter DNA-methylation, even though hundreds of genes were robustly differentially expressed across distantly relatedbreeds. Several of the differentially expressed genes are known to affect behavior, and as suggested from their functionalannotation, we found that female Red Junglefowl are more explorative and fearful in a range of tests performed throughouttheir lives. This paper identifies new sites and, with increased resolution, confirms known sites where DNA-methylationseems to affect sexually dimorphic gene expression, but the general lack of this association is noticeable and strengthensthe view that birds do not have dosage compensation.

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