Department of Ecology and Genetics, Division of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.
Nat Ecol Evol. 2020 May;4(5):737-744. doi: 10.1038/s41559-020-1140-7. Epub 2020 Mar 16.
Sexual selection depletes genetic variation but depleted genetic variation limits the efficacy of sexual selection-a long-standing enigma known as the lek paradox. Here we offer a twist to this paradox by showing that sexual selection and the generation of new genetic variation via mutation may be entangled in an evolutionary feedback loop. We induced DNA damage in the germline of male seed beetles evolved under regimes manipulating the opportunity for natural and sexual selection, and quantified de novo mutations in F2-F7 generations by measuring mutation load. Sexually selected males passed on smaller loads, suggesting that selection for male quality not only purges segregating deleterious alleles, but can also reduce the rate at which such alleles originate de novo. However, when engaging in socio-sexual interactions, males evolved exclusively under sexual selection transferred greater loads, suggesting that trade-offs between naturally and sexually selected fitness components can increase mutation rate. These results offer causality to the widely observed male mutation bias and have implications for the maintenance of genetic variation in fitness.
性选择会耗尽遗传变异，但遗传变异的耗尽又会限制性选择的效果——这是一个长期以来被称为“炫耀悖论”的谜团。在这里，我们通过展示性选择和通过突变产生新遗传变异之间可能存在进化反馈循环，对这个悖论进行了新的解读。我们在经过自然选择和性选择机会操纵的雄性种子甲虫的生殖细胞系中诱导 DNA 损伤，并通过测量突变负荷来量化 F2-F7 代的新突变。经过性选择的雄性传递的突变负荷较小，这表明对雄性质量的选择不仅可以清除分离的有害等位基因，还可以降低这些等位基因从头产生的速度。然而，当雄性在进行社会性行为时，它们只在性选择下进化，传递的突变负荷更大，这表明自然选择和性选择的适应性成分之间的权衡可能会增加突变率。这些结果为广泛观察到的雄性突变偏倚提供了因果关系，并对适应性遗传变异的维持具有重要意义。
