Phylogenetic assessment within a species complex of a subterranean rodent (Geomys bursarius) with conservation implications for isolated subspecies

Range contraction and expansion from glaciation has led to genetic
divergence that may be particularly pronounced in fossorial species with
low dispersal. The plains pocket gopher (Geomys bursarius) is a fossorial
species that ranges widely across North America but has a poorly
understood phylogeny. We used mitogenomes (14,996 base pairs) from 56
individuals across seven subspecies, plus two outgroup species, to assess
genetic divergence from minimum spanning trees, measure genetic distances,
and infer phylogenetic trees using BEAST. We found G. b. wisconsinensis
was monophyletic with recent divergence. Further assessment is needed for
G. b. major because it was paraphyletic and exhibited inconsistent
groupings with other clades. Importantly, we identified G. b. illinoensis
as being genetically distinct and monophyletic likely due to a unique
colonization event eastward across the Mississippi River. Because G. b.
illinoensis faces continued pressures from niche reduction and habitat
loss, we recommend that G. b. illinoensis be considered an evolutionary
significant unit warranting conservation actions to promote connectivity
and restore suitable habitat. Such conservation efforts should benefit
other grassland species including those originating from clades west of
the Mississippi River that may also be evolutionary significant units.