Data from: Environmental complexity and the purging of deleterious alleles

Sexual interactions among adults can generate selection on both males and females with genome-wide consequences. Sexual selection through males is one component of this selection that has been argued to play an important role in purging deleterious alleles. A common technique to assess the influence of sexual selection is by a comparison of experimental evolution under enforced monogamy vs. polygamy. Mixed results from past studies may be due to the use of highly simplified lab conditions that alter the nature of sexual interactions. Here we examine the rate of purging of 22 gene disruption mutations in experimental polygamous populations of Drosophila melanogaster in each of two mating environments: a simple, high density environment (i.e., typical fly vials) and a lower density, more spatially complex environment. Based on past work, we expect sexual interactions in the latter environment to result in stronger selection in both sexes. Consistent with this, we find that mutations tend to be purged more quickly in populations evolving in complex environments. We discuss possible mechanisms by which environmental complexity might modulate the rate at which deleterious alleles are purged and putatively ascribe a role for sexual interactions in explaining the treatment differences in our experiment.

成年个体间的性互作（sexual interactions）可对雌雄两性施加选择压力，并产生全基因组层面的影响。通过雄性介导的性选择（sexual selection）是此类选择的组成部分，此前研究认为其在清除有害等位基因（deleterious alleles）过程中发挥关键作用。评估性选择影响的常用实验方法，是对比强制单配偶制（enforced monogamy）与多配偶制（polygamy）条件下的实验进化（experimental evolution）结果。既往研究得到的结果存在分歧，这可能源于实验采用了高度简化的实验室培养环境——该环境会改变性互作的固有特性。本研究以多配偶制的黑腹果蝇（Drosophila melanogaster）实验种群为对象，在两种交配环境下分别检测22个基因打断突变（gene disruption mutations）的清除速率：一种为简单高密度环境（即常规果蝇培养管），另一种为低密度且空间结构更复杂的环境。基于既往研究，我们推测后一种环境中的性互作会对两性施加更强的选择压力。实验结果与该预期一致：在复杂环境中进化的种群，其有害突变的清除速率显著更快。本研究探讨了环境复杂度调控有害等位基因清除速率的潜在机制，并初步将本实验中不同处理组的差异归因于性互作的作用。