Two mitochondrial genes under episodic positive selection in subterranan octodontoid rodents.

Gene

PubMedID: 24113079

Tomasco IH, Lessa EP. Two mitochondrial genes under episodic positive selection in subterranan octodontoid rodents. Gene. 2013;.
Tuco-tucos (Ctenomys) and related coruros (Spalacopus) are South American subterranean rodents. An energetically demanding lifestyle within the hypoxic, underground atmosphere may change the selective regime on oxidative phosphorylation. We examined whether weak and/or episodic positive directional selection affected the evolution of two mitochondrial genes (COX2, CytB), in a background of purifying selection in these lineages. We estimated rates of synonymous (dS) and non-synonymous (dN) substitutions and found: 1) significantly higher dN/dS ratio in subterranean groups relative to non-subterranean related species, and 2) two codons in each gene under episodic selection: 94 and 277 of COX2, 269 and 307 of CytB.