Genetic consequences of social dynamics in the Andean condor: the role of sex and age

Social living can be facilitated by cooperative advantages, yet also incurs in important competitive interactions, leading to complex patterns of spatial genetic structure. Vultures provide a valuable example of complex social animals, with potential conflicts between cooperative and competitive behaviors. Yet, little is known about the socio-genetic structure of this guild because of the inherent difficulties of sampling highly mobile species with large geographical ranges. Herein, we genotyped 300 non-invasive samples from Andean condor (Vultur gryphus) with microsatellite markers to investigate the social dynamics in this highly vagile vulture that possess a despotic social system and communal roosting behavior. We explored the role of age and sex in the dispersion and relatedness patterns of the Andean condor across the central region of Argentina. We provided evidence of age-biased dispersal, supporting the idea that immature condors are largely nomadic using temporary roosting sites during exploratory flights. Our results also insinuated that sex-biased dispersal is age-dependent, with male-biased dispersal during the early life stage, suggesting habitat exclusion by adult male despotic competition. Finally, our kinship analysis showed that regional clusters are composed of highly related adults, indicating the retention of intergenerational family members. Collectively, these results demonstrate that kin associations are driven by adult philopatry, and possibly maintained by fitness benefits of social cooperation for this species. SIGNIFICANCE STATEMENT: An important question in behavioral ecology is how and when does group living affect population structure and space use. We show that adult Andean condors exhibit philopatric behavior, resulting in kin structuring patterns. Family coalitions may facilitate cooperative strategies to locate and secure costly resources, resulting in indirect fitness benefits. However, immature individuals seem to be excluded from adult territories due to despotic competition or because of an innate exploratory behavior, resulting in a scattered distribution pattern. Understanding the genetic consequences of social dynamics not only increase our knowledge of the behavioral ecology of elusive wide-ranging species, but is also essential in wildlife monitoring to design effective genetic sampling.