Social and spatial effects on genetic variation between foraging flocks in a wild bird population |
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| Authors: | Reinder Radersma Colin J. Garroway Anna W. Santure Isabelle de Cauwer Damien R. Farine Jon Slate Ben C. Sheldon |
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| Affiliation: | 1. Edward Grey Institute, Department of Zoology, University of Oxford, Oxford, UK;2. Department of Biology, Lund University, Lund, Sweden;3. Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada;4. Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK;5. School of Biological Sciences, The University of Auckland, Auckland, New Zealand;6. Univ. Lille, CNRS, UMR 8198 – Evo‐Eco‐Paleo, Lille, France;7. Department of Collective Behaviour, Max Planck Institute for Ornithology, Konstanz, Germany;8. Chair of Biodiversity and Collective Behaviour, Department of Biology, University of Konstanz, Konstanz, Germany |
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| Abstract: | Social interactions are rarely random. In some instances, animals exhibit homophily or heterophily, the tendency to interact with similar or dissimilar conspecifics, respectively. Genetic homophily and heterophily influence the evolutionary dynamics of populations, because they potentially affect sexual and social selection. Here, we investigate the link between social interactions and allele frequencies in foraging flocks of great tits (Parus major) over three consecutive years. We constructed co‐occurrence networks which explicitly described the splitting and merging of 85,602 flocks through time (fission–fusion dynamics), at 60 feeding sites. Of the 1,711 birds in those flocks, we genotyped 962 individuals at 4,701 autosomal single nucleotide polymorphisms (SNPs). By combining genomewide genotyping with repeated field observations of the same individuals, we were able to investigate links between social structure and allele frequencies at a much finer scale than was previously possible. We explicitly accounted for potential spatial effects underlying genetic structure at the population level. We modelled social structure and spatial configuration of great tit fission–fusion dynamics with eigenvector maps. Variance partitioning revealed that allele frequencies were strongly affected by group fidelity (explaining 27%–45% of variance) as individuals tended to maintain associations with the same conspecifics. These conspecifics were genetically more dissimilar than expected, shown by genomewide heterophily for pure social (i.e., space‐independent) grouping preferences. Genomewide homophily was linked to spatial configuration, indicating spatial segregation of genotypes. We did not find evidence for homophily or heterophily for putative socially relevant candidate genes or any other SNP markers. Together, these results demonstrate the importance of distinguishing social and spatial processes in determining population structure. |
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| Keywords: | eigenvector maps
Parus major
population genetics single nucleotide polymorphisms social networks |
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