Data from: Strong sexual selection in males against a mutation load that reduces offspring production in seed beetles

Theory predicts that sexual reproduction can increase population viability relative to asexual reproduction by allowing sexual selection in males to remove deleterious mutations from the population without large demographic costs. This requires that selection acts more strongly in males than females and that mutations affecting male reproductive success have pleiotropic effects on population productivity, but empirical support for these assumptions is mixed. We used the seed beetle Callosobruchus maculatus to implement a three-generation breeding design where we induced mutations via ionizing radiation (IR) in the F0 generation, measured mutational effects (relative to non-irradiated controls) on an estimate of population productivity in the F1, and effects on sex-specific competitive lifetime reproductive success (LRS) in the F2. Regardless of whether mutations were induced via F0 males or females, they had strong negative effects on male LRS, but a non-significant influence on female LRS, suggesting that selection is more efficient in removing deleterious alleles in males. Moreover, mutations had seemingly shared effects on population productivity and competitive LRS in both sexes. Thus, our results lend support to the hypothesis that strong sexual selection on males can act to remove the mutation load on population viability, thereby offering a benefit to sexual reproduction.理论预测，相较于无性生殖，有性生殖可提升种群生存力，其机制在于允许雄性间的性选择在无需付出高昂种群统计成本的前提下，清除种群中的有害突变。这一机制需要满足两个前提：其一，选择在雄性群体中的作用强度高于雌性；其二，影响雄性繁殖成功的突变会对种群生产力产生多效性影响，但现有针对这些假设的实证研究结果并不一致。我们以绿豆象（Callosobruchus maculatus）为实验对象，采用三代繁育设计：在亲本代（F0）通过电离辐射（IR）诱导突变，于子一代（F1）检测突变对种群生产力评估指标的影响（相较于未辐照对照组），并在子二代（F2）检测突变对两性特异性竞争性终生繁殖成功率（LRS）的影响。无论突变是通过F0雄性还是雌性诱导产生，其均对雄性LRS产生显著负向影响，但对雌性LRS的影响未达到统计学显著性，这表明雄性群体在清除有害等位基因方面的选择效率更高。此外，突变似乎对两性的种群生产力与竞争性LRS均产生了相似的影响。综上，本研究结果支持如下假说：对雄性的强性选择可清除种群生存力相关的突变负荷，从而为有性生殖带来演化优势。