Hitchhiking of Deleterious Alleles and the Cost of Adaptation in Partially Selfing Species
Hitchhiking of Deleterious Alleles and the Cost of Adaptation in Partially Selfing Species
复制标题
DOI：
10.1534/genetics.113.158196
复制
发表时间：
2014-01-01
期刊：
影响因子：
3.3
通讯作者：
Glemin, Sylvain
中科院分区：
文献类型：
--
作者：
Hartfield, Matthew;Glemin, Sylvain
从长远来看，自体受精通常被认为是不利的。它增加了遗传漂变，从而降低了多态性和选择效率，这也对适应提出了挑战。然而，高自交率可以增加隐性有益突变的固定概率，但现有理论通常没有考虑连锁位点的影响。在这里，我们分析了有害突变体的固定概率模型，这些突变体在二倍体、部分自交群体中选择性扫描。近似分析解表明，在扫描不因漂移而丢失的条件下，较高的近交率会增加有害等位基因的固定概率，因为由此导致多态性和有效重组的减少。当扩展分析以考虑有害等位基因的分布以及扫描后平均适应度增加时，我们发现有益等位基因通常需要比先前假设的显性阈值（h < 1/2）更加隐性，以便自交从单基因座理论中受益。我们的结果强调，与单基因座理论获得的结果相比，有助于多基因座选择效率的重组放大了异交相对于自交的适应性益处。这种效应还增加了参数范围，在该范围内，专性异交比部分自交更有利。
Self-fertilization is generally seen to be disadvantageous in the long term. It increases genetic drift, which subsequently reduces polymorphism and the efficiency of selection, which also challenges adaptation. However, high selfing rates can increase the fixation probability of recessive beneficial mutations, but existing theory has generally not accounted for the effect of linked sites. Here, we analyze a model for the fixation probability of deleterious mutants that hitchhike with selective sweeps in diploid, partially selfing populations. Approximate analytical solutions show that, conditional on the sweep not being lost by drift, higher inbreeding rates increase the fixation probability of the deleterious allele, due to the resulting reduction in polymorphism and effective recombination. When extending the analysis to consider a distribution of deleterious alleles, as well as the average fitness increase after a sweep, we find that beneficial alleles generally need to be more recessive than the previously assumed dominance threshold (h < 1/2) for selfing to be beneficial from one-locus theory. Our results highlight that recombination aiding the efficiency of selection on multiple loci amplifies the fitness benefits of outcrossing over selfing, compared to results obtained from one-locus theory. This effect additionally increases the parameter range under which obligate outcrossing is beneficial over partial selfing.