Data from: Intralocus sexual conflict and environmental stress

Intralocus sexual conflict (ISC) occurs when selection at a given locus favors different alleles in males and females, placing a fundamental constraint on adaptation. However, the relative impact of ISC on adaptation may become reduced in stressful environments that expose conditionally deleterious mutations to selection. The genetic correlation for fitness between males and females (rMF) provides a quantification of ISC across the genome. We compared ISC at a benign (29˚C) and a stressful (36˚C) temperature by estimating rMFs in two natural populations of the seed beetle Callosobruchus maculatus using isofemale lines. In one population, we found substantial ISC under benign conditions signified by a negative rMF (-0.51) and, as predicted, a significant reduction of ISC under stress signified by a reversed and positive rMF (0.21). The other population displayed low ISC at both temperatures (rMF: 0.38; 0.40). In both populations, isofemale lines harboring alleles beneficial to males but detrimental to females at benign conditions tended to show overall low fitness under stress. These results offer support for low ISC under stress and suggest that environmentally sensitive and conditionally deleterious alleles that are sexually selected in males mediate changes in ISC. We discuss implications for adaptive evolution in sexually reproducing populations.基因座内性冲突（Intralocus sexual conflict, ISC）指当某一基因座上的选择在雄性与雌性中青睐不同等位基因时所发生的现象，该过程会对生物适应过程构成根本性约束。然而，在能够使条件性有害突变暴露于选择压力的胁迫环境中，ISC对适应的相对影响可能会减弱。雌雄个体间的适合度遗传相关系数（genetic correlation for fitness between males and females, rMF）可用于量化全基因组范围内的ISC。本研究以豇豆象（Callosobruchus maculatus）的两个自然种群为研究对象，采用等雌系（isofemale lines）估算rMF，以此对比温和环境（29℃）与胁迫环境（36℃）下的ISC水平。在其中一个种群中，我们在温和环境下观测到显著的ISC，表现为负向rMF（-0.51）；而正如预期，胁迫环境下ISC显著减弱，表现为rMF逆转呈正向（0.21）。另一个种群在两种温度条件下均表现出较低的ISC（rMF分别为0.38与0.40）。在两个种群中，携带在温和环境下对雄性有益、但对雌性有害的等位基因的等雌系，在胁迫环境下的整体适合度往往较低。上述结果支持了“胁迫环境下ISC水平降低”这一结论，并表明：在雄性中受性选择的、对环境敏感且具有条件有害性的等位基因，介导了ISC的动态变化。本研究最后讨论了该发现对有性繁殖种群适应进化的启示。