Genetic lag in a demographically recovering carnivore: the case of the British pine marten (Martes martes)

We investigated the genetic diversity of the contemporary Scottish pine marten population using neutral microsatellite markers, sampling 206 individuals across an area of almost 32,000 km2. Our results revealed that the genetic diversity in the Scottish population is modest with the levels of observed and expected heterozygosity ranging from the Highlands (Ho 0.52, He 0.55) to the Cairngorms (Ho 0.44, He 0.42), and the number of alleles ranged from 3.3 in the Highlands and Central to 2.3 in Dumfries and Galloway, but there were high levels of genetic admixture across the country, some of which may be attributed to natural demographic recovery from previously isolated refuges, and unofficial translocations have also influenced the genetic mixing evident in the population today. Genetic sub structuring, resulting in the Wahlund effect, complicated evaluations of diversity, effective population size, and bottlenecks, and commonly used linkage disequilibrium methods for estimating effective population size yielded improbably low figures. A less commonly used method relying on sibship proved more resilient to the effects of genetic sub structuring, but still yielded estimates under 200, below the suggested viability threshold for long-term population survival. Despite demographic expansion, genetic recovery lagged, suggesting the need for increased gene flow through wildlife corridors.