History matters: contemporary versus historic population structure of bobcats in the New England region, USA

Habitat fragmentation and genetic bottlenecks can have substantial impacts on the health and management of wildlife species by lowering diversity and subdividing populations. Population genetic comparisons across time periods can help elucidate temporal changes in populations and the processes responsible for the changes. Bobcats (Lynx rufus) are wide-ranging carnivores and are currently increasing in abundance across an expanding range. Bobcat populations in New England have fluctuated in the past century in response to changes in their prey base, harvest pressure, and landscape development. We genotyped contemporary (2010-2017) and historic (1952-1964) bobcats from New England and Quebec, Canada at a suite of microsatellite loci and tested for differences in diversity, effective population size, and gene flow. Over 20 generations separated the sampling periods, and the intervening years were marked by drastic changes in land use and species management regimes. We found a general decrease in genetic diversity and differing population genetic structure through time. Effective population size decreased at the end of the historic period, coincident with a spike in harvest, but rebounded to greater numbers in the contemporary period. Our results suggest that bobcat populations in the region are robust, but development and range dynamics may play a significant role in population structure. Our study also highlights the benefits of a historical perspective in interpreting contemporary population genetic data.