Geographic Variation in the Pocket Gopher, Cratogeomys castanops, in Coahuila, México

In this detailed field study, the authors chart the distribution of the plateau pocket gopher, Cratogeomys castanops, across the varied landscape of Coahuila, México. Drawing on more than 200 specimens from dozens of locations, they refine earlier classifications and describe four new subspecies, bringing the total to eleven within the state. The narrative explains how mountains, rivers, and soil types act as natural separators, shaping distinct evolutionary lines in this otherwise sedentary rodent.

Three primary habitats emerge from the description: a humid lowland plain extending from the coastal region, a drier high‑elevation plateau, and the rugged valleys of the Sierra Madre Oriental. Within each zone, related subspecies share more characteristics with one another than with those across the neighboring zones, underscoring the impact of geography on genetic drift. Listeners will hear vivid accounts of soil textures, underground tunnel systems, and the subtle ways a river canyon can halt an entire population, offering a window into the quiet forces that sculpt biodiversity.