Genetic differentiation in sympatric species of chewing lice (Mallophaga, Trichodectidae)

Starch-gel electrophoresis was used to assess levels of genetic differentiation among populations representing four species of chewing lice (Geomydoecus). These species included representatives of the subgenera Geomydoecus and Thomomydoecus that coexist on individual pocket gophers (Thomomys). Fourteen enzymatic loci were resolved from individual chewing lice. Samples of conspecific lice collected from different individual pocket gophers at a single locality sometimes showed marked differences in allele frequencies. Conspecific samples of lice collected from geographically distant host populations had levels of genetic differentiation similar to those of other conspecific insect populations. Levels of Nei's genetic identity (I) within each subgenus were typical of nonsibling species of insects. The subgenera Geomydoecus and Thomomydoecus had a mean Nei's I value of 0.332. This value is characteristic of intergeneric comparisons for insects, and it supports the elevation of these subgenera to generic rank.