Spatial heterogeneity in genetic relatedness among house sparrows along an urban-rural gradient as revealed by individual-based analysis

Understanding factors that shape patterns of kinship in sedentary species is important for evolutionary ecologists as well as conservation biologists. Yet, how patterns of relatedness are hierarchically structured in space remains poorly known, even in common species. Here we use information from 16 polymorphic microsatellite DNA markers to study how small-scale kinship structure varies among house sparrows (Passer domesticus) along an urban-rural gradient. Average levels of relatedness were higher among urban individuals than among individuals from rural areas, suggesting lower rates of dispersal in more built up habitats. Comparison of observed levels of relatedness with simulated distributions of known kinship values showed that central urban individuals had the highest proportion of closely-related conspecifics in their immediate neighbourhood. Spatial auto-correlograms supported this small-scale genetic structure and further indicated stronger effects of genetic drift and/or limite...