Rhodopsin Molecular Evolution in Mammals Inhabiting Low Light Environments

Zhao, Huabin; Ru, Binghua; Teeling, Emma C.; Faulkes, Christopher G.; Zhang, Shuyi; Rossiter, Stephen J.

The results of sliding window analyses are presented in Figure 2 . Estimates of v values were found to be low for the alignment of rhodopsin coding sequences for all mammals (shown in black), suggesting purifying selection as the main force during rhodopsin evolution. However, higher v estimates were found in African mole-rats, cetaceans and pinnipeds (Figure 2A , B and C), indicative of elevated evolutionary rates. In pinnipeds, the v ratio exceeded one in two regions, suggesting positive selection. All of the regions with higher v values were transmembrane and extracellular domains. In bats, v ratios were not obviously greater than in mammals in general ( Figure 2D ), though v ratios were elevated in high-duty-cycle echolocating bats (data not shown).