Genetic data disagree with described subspecies ranges for Seaside Sparrows on the Atlantic coast

Seaside Sparrows (Ammospiza maritima) are tidal salt marsh endemic passerines found along the Atlantic and Gulf coasts of North America. Currently there are 7 described subspecies and \"MacGillivray's\" Seaside Sparrow (A. m. macgillivraii) is the name given to the Atlantic coast subspecies breeding from North Carolina to northern Florida. In 2019 the US Fish and Wildlife Service received a petition to list this subspecies under the Endangered Species Act due to shrinking populations and loss of marsh habitat, which necessitated a Species Status Assessment. As part of the Species Status Assessment, we analyzed genetic (microsatellite and mitochondria) data from 464 Seaside Sparrows from Connecticut to Florida, USA, to infer population connectivity (gene flow) among Atlantic coast populations, and to assess the concordance of population genetic data with the putative ranges of the subspecies. Bayesian cluster analysis (program Structure) indicates three genetically distinct population segm...