Aim The Mohave ground squirrel ( Xerospermophilus mohavensis ) is one of a few endemic species of the Mojave Desert of south‐western North America. We describe phylogeographic patterns within this species and its sister taxon ( Xerospermophilus tereticaudus ) and test hypotheses concerning their biogeographical history using genetic signatures of stable versus expanding populations. We compare these patterns with those of othe...