Genetic reassessment of population subdivision in Yellowstone National Park bison.

Yellowstone National Park is home to the only plains bison population that has continually existed as wildlife, on the same landscape, through the population bottleneck of the late 19th century. Nevertheless, by the early 1900s, only 23 wild bison were known to have survived poaching. Salvation efforts included the addition of 18 females from Montana and 3 bulls from Texas to augment this population. A century later, nuclear microsatellite-based population-level assessment revealed two genetically distinct bison subpopulations. However, in 2016, an analysis of mitochondrial haplotypes showed the two founding lineages were distributed throughout the park. This study is designed to delineate any current substructure in the Yellowstone bison population by strategically sampling the two major summer breeding herds and the two major winter ranges. Population-level metrics were derived using the same microsatellite loci as the original study along with a newly developed set of highly informative bison-specific single nucleotide polymorphisms. Our analyses reveal that the modern bison in Yellowstone National Park currently consists of one interbreeding population, composed of two subunits.