The impact of urbanization on genetic connectivity of 10 mammal species in New Jersey

Rapid human modification of landscapes around the world has made understanding how humans affect the genetic connectivity of wildlife populations urgent. The consistency of anthropogenic impact on genetic connectivity across taxa is unclear, in part because it is rare to have data representing functional connectivity for multiple taxa on the same landscape. We use microsatellite data for 10 mammalian species in New Jersey, USA, to assess cross-taxonomic patterns in the impact of urbanization on genetic connectivity. In doing so, we also evaluate the efficacy of species-specific and species-agnostic approaches for representing landscape resistance in landscape genetics analyses. We found relative consistency in the relationship between genetic connectivity and a resistance surface built using a species-agnostic index of human modification. High levels of human modification impeded genetic connectivity in 7/10 species. However, despite this relative consistency, for 7/10 species the highest performing resistance surfaces reflected a suite of variables individually tailored to each species' ecology, rather than species-agnostic representations of human infrastructure. Other land cover covariates, like forest, shrub, and herbaceous cover, consistently facilitated genetic connectivity. These results show that while human modification of the environment is important in explaining patterns of genetic connectivity across taxa, there is enough variation in how species respond to the suite of factors that define a landscape that functional connectivity is not always well represented by human modification alone.