Mating systems and the efficacy of selection at the molecular level
Mating systems and the efficacy of selection at the molecular level
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DOI：
10.1534/genetics.107.073601
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发表时间：
2007-10-01
期刊：
影响因子：
3.3
通讯作者：
Glemin, Sylvain
中科院分区：
文献类型：
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作者：
Glemin, Sylvain
交配系统通过影响有效群体大小（N-e）和有效重组率在分子进化中起着关键作用。由于自交系中N-e选择的减少，物种的选择效率被认为是较低的，允许固定弱有害等位基因或降低适应性，这可能危及它们的长期进化。通过分析非同义和同义分歧的比率D-n/D-s或非同义和同义多态性的比率pi（n）/pi（s），可以在分子水平上检测到自交者的松弛选择压力。另一方面，自交揭示了隐性等位基因的选择（纯合性效应），这可能会抵消减少N-E通过群体遗传学模型，本研究调查的过程中可能占主导地位的自然群体和条件是必要的，以检测放松选择签名的证据在分子水平上的卖方。在一个合理的群体和突变参数范围内，对有害突变的宽松选择应该是可检测的，但两种交配系统之间的差异可能很弱。在平衡状态下，异交者和自交者之间的差异使用趋异测量（D-n/D-s比率）比使用多态性数据（pi（n）/pi（s）比率）更明显。异交者和自交者之间适应性替代率的差异很难预测，因为它严重取决于新的有利突变的优势水平，而这些突变的优势水平知之甚少。不同的方法来测试这些预测的建议，这些结果的自我繁殖物种的进化的影响进行了讨论。
Mating systems are thought to play a key role in molecular evolution through their effects on effective population size (N-e) and effective recombination rate. Because of reduced N-e selection in self-fertilizing species is supposed to be less efficient, allowing fixation of weakly deleterious alleles or lowering adaptation, which may jeopardize their long-term evolution. Relaxed selection pressures in selfers should be detectable at the molecular level through the analyses of the ratio of nonsynonymous and synonymous divergence, D-n/D-s or the ratio of nonsynonymous and synonymous polymorphism, pi(n)/pi(s). On the other hand, selfing reveals recessive alleles to selection (homozygosity effect), which may counterbalance the reduction in N-e Through population genetics models, this study investigates which process may prevail in natural populations and which conditions are necessary to detect evidence for relaxed selection signature at the molecular level in sellers. Under a Aide range of plausible population and mutation parameters, relaxed selection against deleterious mutations should be detectable, but the differences between the two mating systems can be weak. At equilibrium, differences between outcrossers and selfers should be more pronounced using divergence measures (D-n/D-s ratio) than using polymorphism data (pi(n)/pi(s) ratio). The difference in adaptive substitution rates between outcrossers and selfers is much less predictable because it critically depends on the dominance levels of new advantageous mutations, which are poorly known. Different ways of testing these predictions are suggested, and implications of these results for the evolution of self-fertilizing species are also discussed.