Parallel and Convergent Evolution of the Dim-Light Vision Gene RH1 in Bats Order: ChiropteraReportar como inadecuado

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Rhodopsin, encoded by the gene Rhodopsin RH1, is extremely sensitive to light, and is responsible for dim-light vision. Bats are nocturnal mammals that inhabit poor light environments. Megabats Old-World fruit bats generally have well-developed eyes, while microbats insectivorous bats have developed echolocation and in general their eyes were degraded, however, dramatic differences in the eyes, and their reliance on vision, exist in this group. In this study, we examined the rod opsin gene RH1, and compared its evolution to that of two cone opsin genes SWS1 and M-LWS. While phylogenetic reconstruction with the cone opsin genes SWS1 and M-LWS generated a species tree in accord with expectations, the RH1 gene tree united Pteropodidae Old-World fruit bats and Yangochiroptera, with very high bootstrap values, suggesting the possibility of convergent evolution. The hypothesis of convergent evolution was further supported when nonsynonymous sites or amino acid sequences were used to construct phylogenies. Reconstructed RH1 sequences at internal nodes of the bat species phylogeny showed that: 1 Old-World fruit bats share an amino acid change S270G with the tomb bat; 2 Miniopterus share two amino acid changes V104I, M183L with Rhinolophoidea; 3 the amino acid replacement I123V occurred independently on four branches, and the replacements L99M, L266V and I286V occurred each on two branches. The multiple parallel amino acid replacements that occurred in the evolution of bat RH1 suggest the possibility of multiple convergences of their ecological specialization i.e., various photic environments during adaptation for the nocturnal lifestyle, and suggest that further attention is needed on the study of the ecology and behavior of bats.

Autor: Yong-Yi Shen, Jie Liu, David M. Irwin, Ya-Ping Zhang



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