Hidden dispersal in an urban world: limited dispersal barriers for Dutch pine martens

Especially in urbanized landscapes, habitat fragmentation and increasing numbers of infrastructural features may limit genetic exchange among wildlife populations. Yet, the effects of such urban barriers have only been studied for a limited number of species, and rarely at a spatial scale that truly reflects the distances over which the study species may regularly disperse. We analysed genotypic data from 270 pine martens (Martes martes) sampled from locations scattered across the Netherlands, one of the most densely populated areas in the world. We assessed levels of variation and tested for spatial genetic structure using a variety of Bayesian clustering models. We find very low levels of genetic differentiation, and clear indications of long-distance dispersal. Any substructure detected by the models is likely due to confounding effects of isolation by distance and sampling of close relatives. Our results indicate that genetic exchange among Dutch pine martens has, until now, not been limited by the countries’ dense infrastructural network. The species is likely able to maintain its current high levels of diversity even in a highly urbanized landscape. This surprising conclusion supports the idea that the effects of habitat fragmentation may strongly differ between (groups of) species, and that prioritization and optimization of management decisions thus requires direct study of the targeted species.