Genetic structure of European pine martens (Martes martes), and evidence for introgression with M. americana in England

European pine martens (Martes martes)were once distributed across much ofwestern Europe. A combination of factors, suchas persecution, trapping, and habitat loss haveled to sharp declines in the species' numbersand range and, as such, local populations havebecome more vulnerable to extinction. Toevaluate the influence of these factors on boththe level of genetic variation and populationstructure, we genotyped pine martens fromacross much of their current distribution. Continental M. martes populations werefound to have a higher level of geneticstructure and lower genetic variation thantheir North American sibling species, M.americana, sampled throughout Canada. Thedifferences among mainland populations of thesespecies may lie in greater levels of habitatfragmentation and persecution experienced byEuropean martens, though it is difficult toexclude more ancient processes such as theinfluence of glaciations. Among islandpopulations of the two species, the Scottishpopulation revealed a similar level ofstructure and variation to the M. a.atrata population of Newfoundland, howeverIreland was more differentiated with lessgenetic variation. Our work usingmicrosatellites also extends previous mtDNAevidence for the presence of M. americanahaplotypes in England, raising the possibilityof hybridization with M. martes. Thesefindings may influence current discussions onthe status of English martens and theappropriateness of proposed re-introductions byrevealing that some indigenous martens persistin England, despite the presence of somepotential hybrids in the region.