Anthropogenic habitat modification is linked with variation in dispersal dynamics, social kinship, and genetic structure in a cooperative breeder

Anthropogenic habitat modification can reshape dispersal dynamics, social organisation, and ultimately the genetic structure of populations. In cooperatively breeding species, where philopatry and helping are common, dispersal events are rare but critical for maintaining gene flow and reducing inbreeding. Using microsatellite data (N = 211 individuals) and long-term (1985 - 2023) social kinship data from the cooperatively breeding Arabian babblers (Argya squamiceps) living in natural and modified habitats in the hyper-arid Arava Valley (Israel), we examined how habitat modification influences the social and genetic structure. We combined spatial autocorrelation analyses, within-group relatedness estimates, and social kinship to assess patterns of dispersal, connectivity, and kinship across habitats. We found high gene flow across habitats and only weak differentiation among subpopulations, consistent with recent habitat changes that do not produce strong divergence. However, subtle but significant differences emerged between natural and modified habitats. Groups inhabiting modified areas showed shorter dispersal distances and lower within-group relatedness, suggesting higher turnover and increased immigration of unrelated individuals. In contrast, groups in natural habitats maintained stronger kin-based cohesion and broader positive spatial genetic structure. Our results indicate that habitat modification does not reduce connectivity in this system but reshapes the balance between philopatry and dispersal, favouring earlier dispersal and reduced kinship within groups. Modified habitats attract and concentrate individuals from multiple origins, while natural habitats function as demographic sources. These findings corroborate previous behavioural evidence of an accelerated pace of life in modified habitats and demonstrate that such life-history adjustments are detectable in the genetic and social structure. More broadly, our study highlights how anthropogenic changes in arid ecosystems can leave rapid genetic signatures in cooperative breeders, underscoring the importance of integrating behavioural, demographic, and genetic perspectives to understand population responses to environmental change.