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.

交配偏好的起源与维持，始终是性选择研究领域中兼具重要性与争议性的核心议题。求偶场（lek）及类求偶场交配体系，指个体仅为完成配偶选择而聚集于特定区域的交配体系，尤为令人费解：因配偶选择施加的强定向选择本应消除竞争个体间的遗传变异，并抵消择偶性别所能获得的任何收益。本研究借助蠕形海龙（Nerophis lumbriciformis）的类求偶场交配体系，验证用于解释交配偏好维持的表型关联生育力假说（phenotype-linked fertility hypothesis）。本研究借助微卫星标记开展亲权分析，并结合标记重捕研究，证实蠕形海龙拥有一种极为类似雌性求偶场的特殊交配体系：雌性个体展现求偶特征，雄性则造访求偶场进行配偶选择。研究结果表明，体表装饰最为发达的雌性个体占据繁殖区域的中心附近位置；与这类雌性交配的雄性，其育幼囊内的卵群更为饱满且卵粒更大，相较于与装饰程度较低的雌性交配的雄性。本研究还通过室内控制实验证实，雌性的体表装饰存在条件依赖性，且能够真实传递其繁殖潜力。综合来看，上述结果与表型关联生育力假说的性别独立版本预测相符——雄性对雌性装饰的偏好，与其生育收益存在显著关联。