Population genetics of red foxes (vulpes vulpes) in the Greater Sydney Region

The Eurasian red fox (Vulpes vulpes) is an invasive predator that causes significant damage to native species and agriculture. In Australian cities, red fox density reaches up to 16 foxes per km2 and is much higher than in surrounding rural and natural bush areas. Limited information on population distributions, genetic mixing and dispersal in urban compared to rural habitats hampers the ability of management authorities to safely and effectively control red foxes in these areas. This study examined whether inferred levels of red fox dispersal differ across three habitats; urban, peri-urban and rural, across the Sydney region. We collected fox carcasses from each of these habitats and genotyped thousands of SNPs from DNA extracted from 94 individuals. We found that geneflow was sufficient prevent localized differences in allele frequency and the estimate of effective population size of red foxes in the Greater Sydney region was 212. Analysis of relatedness showed that dispersal was not sex-biased, and levels of dispersal were significantly less in urban compared with peri-urban and rural habitats. Urban landcover, road, railways, and waterways limited dispersal of red foxes within the Sydney region. These results provide insight into the effect of urbanization on red foxes in Sydney and can be used to tailor management to urban and rural populations.