State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, The Chinese Academy of Sciences, Kunming, China.
PLoS One. 2010 Jan 21;5(1):e8838. doi: 10.1371/journal.pone.0008838.
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.
视蛋白，由基因 Rhodopsin（RH1）编码，对光极为敏感，负责暗光视觉。蝙蝠是栖息在弱光环境中的夜行哺乳动物。大蝙蝠（旧大陆果蝠）的眼睛通常发育良好，而小蝙蝠（食虫蝙蝠）则发展出回声定位，它们的眼睛通常退化了，但在这个群体中，眼睛的差异和对视觉的依赖程度存在显著差异。在这项研究中，我们研究了视杆蛋白基因（RH1），并将其进化与两种视锥蛋白基因（SWS1 和 M/LWS）进行了比较。虽然使用视锥蛋白基因 SWS1 和 M/LWS 进行的系统发育重建产生了与预期相符的种系发生树，但 RH1 基因树将 Pteropodidae（旧大陆果蝠）和 Yangochiroptera 联合在一起，具有非常高的自举值，表明趋同进化的可能性。当使用非同义位点或氨基酸序列构建系统发育树时，趋同进化的假设得到了进一步支持。在蝙蝠种系发生树的内部节点处重建的 RH1 序列显示：（1）旧大陆果蝠与 Tomb蝙蝠共享一个氨基酸变化（S270G）；（2）Miniopterus 与 Rhinolophoidea 共享两个氨基酸变化（V104I、M183L）；（3）氨基酸替换 I123V 独立发生在四个分支上，而 L99M、L266V 和 I286V 的替换分别发生在两个分支上。蝙蝠 RH1 进化过程中发生的多次平行氨基酸替换表明，在适应夜间生活方式的过程中，其生态特化（即各种光照环境）可能发生了多次趋同，这表明需要进一步关注蝙蝠的生态学和行为研究。
