Data from: Selection for alternative male reproductive tactics alters intralocus sexual conflict

Intralocus sexual conflict (IASC) arises when fitness optima for a shared trait differ between the sexes; such conflict may help maintain genetic variation within populations. Sex-limited expression of sexually antagonistic traits may help resolve the conflict, but the extent of this resolution remains a subject of debate. In species with alternative male reproductive tactics, unresolved conflict should manifest more in a more sexually dimorphic male phenotype. We tested this prediction in the bulb mite (Rhizoglyphus robini), a species in which aggressive fighters coexist with benign scramblers. To do this, we established replicated lines in which we increased the proportion of each of the alternative male morphs using artificial selection. After approximately 40 generations, the proportion of fighters and scramblers stabilized at >0.9 in fighter- and scrambler-selected lines, respectively. We then measured several female fitness components. As predicted by IASC theory, female fecundity and longevity was lower in lines selected for fighters and higher in lines selected for scramblers. This finding indicates that sexually selected phenotypes are associated with an ontogenetic conflict that is not easily resolved. Furthermore, we suggest that IASC may be an important mechanism contributing to the maintenance of genetic variation in the expression of alternative reproductive tactics.基因座内性冲突（Intralocus sexual conflict, IASC）指当某一共有性状的两性适合度最适值存在差异时所产生的进化冲突；这类冲突或有助于维持种群内的遗传变异。性拮抗性状的性别限制性表达或可缓解此类冲突，但该缓解的程度迄今仍为学术争议的焦点。对于存在替代雄性生殖策略的物种而言，未被缓解的性冲突会在雄性表型性二态性更为突出的类群中表现得更为显著。我们以球根螨（Rhizoglyphus robini）为研究对象验证了这一预测，该物种的雄性个体同时存在攻击性格斗型与温和游走型两种表型。为此，我们建立了多组重复选育系，通过人工选择提高每种替代雄性表型的种群比例。历经约40代选育后，格斗型选育系与游走型选育系中对应雄性表型的比例分别稳定在0.9以上。随后我们测定了多项雌性适合度组分。正如IASC理论所预测，格斗型选育系的雌性繁殖力与寿命均更低，而游走型选育系的雌性则表现出更高的繁殖力与寿命。这一结果表明，性选择塑造的表型与一种难以轻易缓解的发育冲突相关联。此外，我们提出IASC或为维持替代生殖策略表达的遗传变异的重要机制之一。