Data from: Sexual selection on male body size, genital length and heterozygosity: consistency across habitats and social settings

1. Spatial and temporal variation in environmental factors and the social setting can help to maintain genetic variation in sexually selected traits if it affects the strength of directional selection. A key social parameter which affects the intensity of, and sometimes predicts the response to, mating competition is the operational sex ratio (OSR; ratio of receptive males to females). 2. How the OSR affects selection for specific male traits is poorly understood. It is also unclear how sexual selection is affected by interactions between the OSR and environmental factors, such as habitat complexity, that alter key male-female interactions such as mate encounter rates. 3. Here, we experimentally manipulated the OSR and habitat complexity and quantified sexual selection on male mosquitofish (Gambusia holbrooki) by directly measuring male reproductive success (i.e. paternity). 4. We show that, despite a more equitable sharing of paternity (i.e. higher levels of multiple paternity) under a male-biased OSR, selection on focal male traits was unaffected by the OSR or habitat complexity. Instead, sexual selection consistently, and significantly, favoured smaller bodied males, males with higher genome wide heterozygosity (based on >3000 SNP markers), and males with a relatively long gonopodium (intromittent organ).1. 若环境因子与社会情境的时空变化能够影响定向选择的强度，则可助力维持性选择性状的遗传变异。影响交配竞争强度、并可在一定程度上预测其响应的关键社会参数，为操作性别比（operational sex ratio, OSR；即可交配雄性与雌性的数量比值）。 2. 目前学界对操作性别比如何影响特定雄性性状的选择机制仍知之甚少；同时，操作性别比与栖息地复杂度等环境因子的交互作用，会改变雌雄个体间的关键互动（如配偶相遇概率），其对性选择的影响亦尚不明确。 3. 本研究通过实验操控操作性别比与栖息地复杂度，并通过直接测定雄性繁殖成功率（即父权比例），量化了雄性食蚊鱼（Gambusia holbrooki）所受的性选择压力。 4. 研究结果显示：尽管在雄性偏倚的操作性别比条件下，父权分配更为均衡（即多重父权比例升高），但目标雄性性状所受的选择压力并未受操作性别比或栖息地复杂度的影响。与之相反，性选择始终且显著地青睐体型更小、全基因组杂合度更高（基于超过3000个单核苷酸多态性（Single Nucleotide Polymorphism, SNP）标记）、以及生殖足（intromittent organ，即交接器官）相对更长的雄性个体。