Effect of oceanic straits on gene flow in the recently endangered little brown bat (Myotis lucifugus) in maritime Canada: implications for the spread of white-nose syndrome

Abstract

White-nose syndrome is rapidly spreading in eastern North America, causing mass mortality of hibernating bats. We characterized levels of genetic diversity and population structure of the little brown bat (Myotis lucifugus (Le Conte, 1831)) in eastern Canada to infer the extent to which oceanic straits may be barriers to movement. To quantify metrics of gene flow and infer movement dynamics, we genotyped 679 M. lucifugus at nine nuclear microsatellites (nDNA) and sequenced a portion of the mitochondrial DNA (mtDNA). We found high levels of genetic diversity and little population structure, with ≈13-fold higher differentiation of mtDNA than nDNA markers, suggesting that structuring patterns largely result from female philopatry. Discriminant analysis of principle components suggested that the subtle underlying structure was not concordant with sampling site. Regional differentiation (FST, Dest, Mantel test residuals) is mostly consistent with genetic isolation by distance. However, samples from Newfoundland showed genetic differentiation over and above the effects of distance, lower levels of genetic diversity, and less genetic connectivity with other sampled regions. Despite this, oceanic straits in the Gulf of Saint Lawrence do not appear to create an impenetrable barrier to movement, therefore it may be possible for white-nose syndrome to spread to Newfoundland.