Genetics of a reintroduced swift fox population highlights the need for integrated conservation between neighbouring countries

Abstract

AbstractThe genetic consequences of reintroductions are rarely considered after releases cease, but long‐term viability depends on linked demography and genetic health. Reintroductions of swift foxes Vulpes velox began after 45 years of extirpation from Canada; these have resulted in national down‐listing to ‘threatened’ status, and the re‐establishment of a small contiguous population in Montana, US. Demographic growth has been associated with stable levels of genetic diversity and growing effective population size, but evidence of two genetic clusters, and a recent decline in abundance could be cause for conservation concern depending on underlying mechanisms. We analysed individuals from two time points at 18 microsatellite loci to investigate whether the genetic structure is a consequence of having used two separate release sites and non‐equilibrium population dynamics, but our results suggest that the population is likely at mutation‐ and migration‐drift equilibrium. We examined habitat effects on relative gene flow and found limited evidence for cropland to be a dispersal barrier, but effects of terrain roughness suggest that more rugged landscapes may reduce dispersal capacity. Using parentage analysis we determined maximum dispersal distances of up to 50 km for females and 100 km for males including movements in either direction across the international border, but no mixing of genetic clusters was seen in either country. Greater genetic connectivity among than within respective countries necessitates careful co‐management between Canada, where the species has the highest levels of legislative protection, and contiguous areas of the United States where limited trapping for fur is now permitted. We encourage similar analyses of conservation populations across international borders to determine how optimal genetic management can best mesh with different policies and conservation approaches among countries.