Date of this Version
Distributional patterns of the four species of pocket gophers in southeastern Colorado are variously parapatric, allopatric, or sympatric. More specifically, Geomys bursarius is parapatric with Thomomys talpoides, Thomomys bottae, and Cratogeomys castanops; T. bottae is both sympatric and parapatric with C. castanops; and both C. castanops and T. bottae are allopatric with T. talpoides. Geomys bursarius is restricted to sandy soils and soils of cultivated or otherwise disturbed habitats. Cratogeumys castanops and T. bottae occupy a wide variety of soils but are found most commonly in compacted rangeland soils. Thomomys talpoides is found in well-drained upland soils. The distribution of C. castanops in southeastern Colorado is much more extensive than previously believed. Our new data support the competitive exclusion model with respect to these species but suggest that the geographic relationships among them are more complex than previously supposed.