Genetic relatedness (i.e. identity-by-descent, IBD) plays a central role in the evolution of sociality. Kin selection theory predicts that individuals tend to bias affiliative behaviours towards close relatives, which increases their inclusive fitness. Even though kinship is a key concept, it has been a challenge to generate accurate estimates of dyadic relatedness among social animals. Due to high locus-to-locus variation resulting from Mendelian segregation, traditional estimates of relatedness may be imprecise at the dyadic level, which potentially leads to inaccurate conclusions about the role of kinship in social behaviour. Previous studies have demonstrated that single-nucleotide-polymorphism (SNP) data in high number provide much better estimates of relatedness than previously used methods. Hence, whole genome sequencing (WGS) covering all SNPs across the whole genome deliver the most reliable data. Kinship is a key driver of behavioural preferences in primates, with bonds among relatives leading to higher fitness outcomes. However, there is high variation in the degree of kin bias across primate species, which, to some extent, might be explained by methodological limitations in the estimation of relatedness. Consequently, IBD derived from WGS data offers unique opportunities to understand variance in social preferences and complex kin structures in primates.
In my PhD project, I investigate the influence of fine-scale variation in IBD on sociality in rhesus macaques. I combine IBD gained from WGS data with demographic, behavioural, reproductive and other phenotypic data. Thereby, I will assess the influence of the gradient in IBD on social preference, phenotypic cues and their use in kin recognition. Furthermore, I compare IBD from WGS data with relatedness estimates derived from traditional methods.