Cytochrome b gene selection of subterranean rodent Gansu zokor Eospalax cansus (Rodentia, Spalacidae)

We analyzed the molecular selection of a typical subterranean rodent Gansu zokor (Eospalax cansus) combined with mitochondrial cytochrome b (cytb) and D-loop sequences. A total of 121 samples (from 12 sites belonging to 3 main geographical units: U1, U2, and U3) were sequenced, from which 40 cytb haplotypes and 53 D-loop haplotypes were identified. The results of our tests from two site-specific models (M2a and M8) and one branch-site model (Clade model C) suggest that the evolution of cytb in Gansu zokor is chiefly governed by purifying selection. Moreover, the distribution of non-synonymous mutations and the tests by Clade model C indicated the cytb in U3, where the zokors were confronted with more severe hypoxia because of higher altitude and a colder, drier climate, were facing a higher purifying selection pressure than those in U1 and U2.