Data from: A novel method of comparing mating success and survival reveals similar sexual and viability selection for mobility traits in female tree crickets.

The relationship between sexual and viability selection in females is necessarily different than that in males, as investment in sexual traits potentially comes at the expense of both fecundity and survival. Accordingly, females do not usually invest in sexually-selected traits. However direct benefits obtained from mating, such as nuptial gifts, may encourage competition among females and subsidize investment into sexually-selected traits. We compared sexual and viability selection on female tree crickets Oecanthus nigricornis, a species where females mate frequently to obtain nuptial gifts and sexual selection on females is likely. If male choice determines female mating success in this species, we expect sexual selection for fecundity traits, as males of many species prefer more fecund females. Alternatively, intrasexual scramble or combat competition on females may select for larger jumping legs or wider heads (respectively). We estimated mating success using microsatellite analysis of stored sperm, and estimated relative viability by comparing surviving female O. nigricornis to those captured by a common wasp predator. In support of the scramble competition hypothesis, we found sexual selection for females with larger hind legs and narrower heads. We also found stabilizing viability selection for intermediate head width and hind leg size. As predicted, traits under viability and sexual selection were very similar, and the direction of that selection was not opposing. However, since the shape of sexual and viability selection differs, these episodes of selection may favour different trait sizes.雌性个体所经历的性选择（sexual selection）与存活力选择（viability selection）之间的关联，必然与雄性不同——因为对性征的投入，可能同时以繁殖力与生存能力为代价。因此，雌性通常不会对性选择偏好的性状进行投入。但通过交配获取的直接收益（如婚赠（nuptial gifts）），可能会推动雌性间的竞争，并补贴雌性对性选择性状的投入。我们以黑角树蟋（Oecanthus nigricornis）为研究对象，该物种的雌性会频繁交配以获取婚赠，且雌性存在性选择的可能性较高，并在此物种中比较了雌性个体所受的性选择与存活力选择。若该物种的雌性交配成功率由雄性选择决定，则我们预期会出现针对繁殖力性状的性选择——因为诸多物种的雄性更倾向于选择繁殖力更强的雌性。反之，雌性个体间的种内挤碰竞争（scramble competition）或格斗竞争，可能分别青睐更长的跳跃足与更宽的头部。我们通过对存储精子的微卫星分析（microsatellite analysis）评估雌性的交配成功率，并通过对比存活的黑角树蟋雌性与被常见胡蜂捕食者捕获的个体，估算其相对存活力。结果支持挤碰竞争假说：我们发现雌性的性选择青睐后腿更长、头部更窄的个体。同时，我们还发现针对头部宽度与后腿长度中等值的稳定性存活力选择（stabilizing viability selection）。如预期所示，受存活力选择与性选择作用的性状高度相似，且两类选择的作用方向并不相悖。但由于性选择与存活力选择的作用形式存在差异，这两类选择事件可能会青睐不同尺度的性状。