Genic Differentiation in Pocket Gophers of the Genus Pappogeomys, with Comments on Intergeneric Relationships in the Subfamily Geomyinae

Abstract

Patterns of genetic differentiation revealed by starch-gel electrophoresis of proteins are examined at the species level within the genus Pappogeomys and at the generic level within the subfamily Geomyinae. Data from electrophoresis and morphology indicate that the subgenera Pappogeomys and Cratogeomys of the genus Pappogeomys deserve generic recognition. These data further suggest that the castanops species group (Cratogeomys castanops and C. merriami) is not monophyletic, and that C. gymnurus and C. tylorhinus of the gymnurus species group may be conspecific. Overall patterns of genie and chromosomal variation within Pappogeomys and Cratogeomys are similar to patterns seen in other pocket gopher genera. These patterns are compared to genic and chromosomal variation in Thomomys. The genie data suggest the following intergeneric relationships for the Geomyinae: 1) the tribes (Thomomyini and Geomyini) are distinct, monophyletic assemblages; 2) Orthogeomys and Zygogeomys form a distinct clade; 3) the Pappogeomys-Cratogeomys and Orthogeomys-Zygogeomys lineages may be more closely related to each other than either is to Geomys.