Data from: Social and spatial effects on genetic variation between foraging flocks in a wild bird population

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 1711 birds in those flocks we genotyped 962
individuals at 4701 autosomal single-nucleotide polymorphisms (SNPs). By
combining genome-wide 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 genome-wide heterophily for pure social (i.e. space-independent)
grouping preferences. Genome-wide 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.