Population genetic analysis of the endangered Mottled Duskywing butterfly ( Erynnis martialis ) informs species reintroduction

Species reintroduction or translocation programmes are increasingly used to reverse global declines in biodiversity. Information on genetic diversity and structure within a species can be critical for successful selection of a source population for such programmes. The Mottled Duskywing ( Erynnis martialis ) is a North American butterfly listed as endangered in Canada. A collaborative effort to reintroduce the species to sites in the province of Ontario has been initiated. Using 21 microsatellite markers, we evaluated metrics of genetic diversity, population structure and demographic stability of extant Mottled Duskywing populations in Ontario, Manitoba and neighbouring US states to inform the reintroduction effort. Expected heterozygosity among Mottled Duskywing populations ranged from 0.43 to 0.58. Two populations considered as potential reintroduction sources in Ontario had similar levels of genetic diversity but were significantly genetically differentiated; our genetic analyses suggested either as a suitable source, but we do not recommend mixing the two populations for reintroduction. Populations within approximately 10 km of each other were genetically similar and may experience gene flow, while more distant populations appear to be genetically isolated. These genetic data can be used to inform future reintroductions or population augmentations of the species and to assess genetic status of both remnant and reintroduced populations.