Distinct Evolutionary Patterns Between Two Duplicated Color Vision Genes Within Cyprinid Fishes
Distinct Evolutionary Patterns Between Two Duplicated Color Vision Genes Within Cyprinid Fishes
复制标题
鲤科鱼类中两个重复色觉基因之间的独特进化模式
DOI：
10.1007/s00239-009-9283-9
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发表时间：
2009-10-01
影响因子：
3.9
通讯作者：
He, Shunping
中科院分区：
文献类型：
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作者：
Li, Zhiqiang;Gan, Xiaoni;He, Shunping
本研究以洞穴鱼类资源最丰富的金线鲃属鱼类为研究对象，对鲤科鱼类重复色觉基因（LWS-1和SWS2）的分子进化进行了研究。基于最大可能性的密码子替换方法用于分析视觉基因的进化。我们发现，重复的色觉基因具有不平等的进化速率，这可能导致相关的功能分歧。LWS-1的分歧是强烈的影响，积极的选择，导致口袋形成残留物的比例的替代速度加快。SWS2色素经历了谱系间的趋异选择，没有发现正选择位点，部分鲤科鱼类的LWS-1重复拷贝已成为假基因，但在本研究所检测的鲤科鱼类中，所有SWS2序列在检测区域内保持完整。金线属鱼类LWS-1基因的两个拷贝的假基因化不是随机发生的。一些具有许多形态学特化的金线属洞穴物种似乎高度适应洞穴，在其基因组中保留了色觉基因的完整拷贝。我们发现了一些新的关键位点的氨基酸取代，这可能是未来诱变实验的有趣的靶位点。我们的数据增加了越来越多的证据，重复基因经历较低的选择性限制，在某些情况下，积极的选择基因重复。其中一些观察结果是出乎意料的，可能会提供深入了解洞穴对鱼类色觉基因进化的影响。
We investigated the molecular evolution of duplicated color vision genes (LWS-1 and SWS2) within cyprinid fish, focusing on the most cavefish-rich genus-Sinocyclocheilus. Maximum likelihood-based codon substitution approaches were used to analyze the evolution of vision genes. We found that the duplicated color vision genes had unequal evolutionary rates, which may lead to a related function divergence. Divergence of LWS-1 was strongly influenced by positive selection causing an accelerated rate of substitution in the proportion of pocket-forming residues. The SWS2 pigment experienced divergent selection between lineages, and no positively selected site was found. A duplicate copy of LWS-1 of some cyprinine species had become a pseudogene, but all SWS2 sequences remained intact in the regions examined in the cyprinid fishes examined in this study. The pseudogenization events did not occur randomly in the two copies of LWS-1 within Sinocyclocheilus species. Some cave species of Sinocyclocheilus with numerous morphological specializations that seem to be highly adapted for caves, retain both intact copies of color vision genes in their genome. We found some novel amino acid substitutions at key sites, which might represent interesting target sites for future mutagenesis experiments. Our data add to the increasing evidence that duplicate genes experience lower selective constraints and in some cases positive selection following gene duplication. Some of these observations are unexpected and may provide insights into the effect of caves on the evolution of color vision genes in fishes.