Data from: The lek mating system of the worm pipefish (Nerophis lumbriciformis): a molecular maternity analysis and test of the phenotype-linked fertility hypothesis

The origin and maintenance of mating preferences continues to be an important and controversial topic in sexual selection research. Leks and lek-like mating systems, where individuals gather in particular spots for the sole purpose of mate choice, are particularly puzzling, because the strong directional selection imposed by mate choice should erode genetic variation among competing individuals and negate any benefit for the choosing sex. Here, we take advantage of the lek-like mating system of the worm pipefish (Nerophis lumbriciformis) to test the phenotype-linked fertility hypothesis for the maintenance of mating preferences. We use microsatellite markers to perform a parentage analysis, along with a mark-recapture study, to confirm that the worm pipefish has an unusual mating system that strongly resembles a female lek, where females display and males visit the lek to choose mates. Our results show that the most highly ornamented females occupy positions near the centre of the breeding area, and males mating with these females receive fuller broods with larger eggs compared to males mating with less ornamented females. We also conduct a laboratory experiment to show that female ornaments are condition dependent and honestly signal reproductive potential. Overall, these results are consistent with the predictions of a sex-independent version of the phenotype-linked fertility hypothesis, as male preference for female ornaments correlates with fertility benefits.

择偶偏好的起源与维持，始终是性选择（sexual selection）研究领域中兼具重要学术价值与争议性的核心话题。以个体聚集于特定场所、仅为完成配偶选择为核心特征的求偶场（lek）及类求偶场交配系统，尤为令人费解：因为配偶选择所施加的强定向选择本应消除竞争个体间的遗传变异，并抵消选择性别所能获得的全部收益。本研究借助蠕形海龙（Nerophis lumbriciformis）的类求偶场交配系统，检验表型关联生育力假说（phenotype-linked fertility hypothesis）对择偶偏好维持的解释效力。我们采用微卫星标记（microsatellite markers）开展亲权分析（parentage analysis），并结合标记重捕研究（mark-recapture study），证实蠕形海龙拥有一种近似雌性求偶场的特殊交配系统：雌性个体进行展示行为，雄性个体则造访求偶场以完成配偶选择。研究结果表明，体表装饰最为发达的雌性会占据繁殖区域中心附近的位置，与这类雌性交配的雄性所育幼囊内的卵团更为饱满，且卵粒尺寸显著大于与装饰程度较低的雌性交配的雄性。我们还通过室内控制实验证实，雌性的体表装饰性状依赖于个体自身状态，并能够诚实传递繁殖潜力信息。综上，本研究结果与性别无关版本的表型关联生育力假说的预测相符——雄性对雌性装饰性状的偏好，与其所能获得的生育收益存在显著关联。