Adaptation of Rodents Living in a Highland: Combination of Mitochondrial Introgression and Convergent Molecular Evolution.

Populations of four species of narrow-headed rats of the genus Stenocephalemys were examined for the presence of a mutation in the mitochondrial cytochrome b gene resulting in an amino acid substitution in the translated protein. This substitution was also found in hamsters of the subfamily Sigmodontinae inhabiting the highlands of the Andes. Simulation of three-dimensional structure of the protein showed that this substitution is located in the active site and may have a functional significance. We assumed an independent emergence of this substitution in the populations of two Afroalpine species of Stenocephalemys, which is the first known example of a combination of introgression and convergent molecular evolution.