Positive Darwinian selection in gamete recognition proteins of Strongylocentrotus sea urchins
Positive Darwinian selection in gamete recognition proteins of Strongylocentrotus sea urchins
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DOI：
10.1111/j.1365-294x.2011.05336.x
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发表时间：
2011-12-01
影响因子：
4.9
通讯作者：
Pogson, G. H.
中科院分区：
文献类型：
--
作者：
Pujolar, J. M.;Pogson, G. H.
配子识别蛋白通常经历积极的达尔文选择，比非生殖蛋白进化得更快，但导致其适应性多样化的选择力量尚不清楚。在4种圆心海胆（S.similar to purpuratus， S.similar to droebacachiensis， S.similar to pallidus和S.similar to franciscanus）中，研究了精子结合蛋白与其卵受体（EBR1）形成的同源相互作用蛋白对（EBR1）和海胆卵磷脂suREJ3基因精子受体的两个区域（22和26外显子）的正选择模式。每种生殖蛋白的选择特征不同。在所有谱系中，尽管比较的物种具有高度可变的配子特征，并且在自然界中经历了不同强度和形式的性选择和性冲突，但在结合蛋白中都检测到强烈的正选择信号。在EBR1上观察到较弱的选择，但研究的小区域阻碍了对结合蛋白和EBR1蛋白之间性别冲突程度的清晰理解。在suREJ3基因座上，外显子22发生了多样化选择，而外显子26则没有，这表明这些区域经历了不同的选择压力和进化约束。由于存在12个氨基酸替换突变，分离频率为>0.10，因此在suREJ-22中也检测到与苍白菌相似的s.a rej -22中存在正选择。我们的研究结果表明，性冲突可能是驱动强筋胞心海胆生殖蛋白快速多样化和内部多态性的主要进化机制。
Gamete recognition proteins commonly experience positive Darwinian selection and evolve more rapidly than nonreproductive proteins, but the selective forces responsible for their adaptive diversification remain unclear. We examined the patterns of positive selection in the cognate interacting pair of proteins formed by sperm bindin and its egg receptor (EBR1) and in two regions of the sea urchin sperm receptor for egg jelly suREJ3 gene (exons 22 and 26) among four species of Strongylocentrotus sea urchins (S.similar to purpuratus, S.similar to droebachiensis, S.similar to pallidus and S.similar to franciscanus). The signatures of selection differed at each reproductive protein. A strong signal of positive selection was detected at bindin in all lineages even though the species compared had highly variable gamete traits and experience different intensities and forms of sexual selection and sexual conflict in nature. Weaker selection was observed at EBR1 but the small region studied precluded a clear understanding of the extent of sexual conflict between bindin and the EBR1 protein. At the suREJ3 locus, diversifying selection was observed in exon 22 but not exon 26, suggesting that these regions experience different selective pressures and evolutionary constraints. Positive selection was also detected within S.similar to pallidus at suREJ-22 because of the presence of 12 amino acid replacement mutations segregating at frequencies >0.10. Our results suggest that sexual conflict may be the predominant evolutionary mechanism driving the rapid diversification of reproductive proteins between, and polymorphism within, strongylocentrotid sea urchins.