Evolutionary ecological analysis of coupled geographic variation of two sympatric rodent species in the Southern Urals

Geometric morphometrics has been used to reveal coupled geographic variation in the mandible shape in two sympatric rodent species, the pygmy wood mouse (Sylvaemus uralensis Pall.) and bank vole (Myodes glareolus Pall.), in the Southern Urals. It has been shown that syntopic samples synchronously collected from the local communities of these species usually display similar, parallel, and unidirectional morphological changes as demonstrated by comparison of species pairs from different localities. The degree of concordance in geographic variation of the species makes it possible to estimate their coevolutionary potential within local communities: the wider the range of ecological conditions under which parallel variation of sympatric species is observed, the higher is their coevolutionary potential.