Data from: Sex roles and mutual mate choice matters during mate sampling

The roles of females and males in mating competition and mate choice have lately proven more variable, between and within species, than previously thought. In nature, mating competition occurs during mate search, and is expected to be regulated by the numbers of potential mates and same-sex competitors. Here, we present the first study to test how a temporal change in sex roles affects mating competition and mate choice during mate sampling. Our model system (the marine fish Gobiusculus flavescens) is uniquely suitable because of its change in sex roles, from conventional to reversed, over the breeding season. As predicted from sex role theory, courtship was typically initiated by males and terminated by females early in the breeding season. The opposite pattern was observed late in the season, at which time several females often simultaneously courted the same male. Mate-searching females visited more males early than late in the breeding season. Our study shows that mutual mate choice and mating competition can have profound effects on female and male behavior. Future work needs to consider the dynamical nature of mating competition and mate choice if we aim to fully understand sexual selection in the wild.

近年来的研究显示，雌雄个体在交配竞争（mating competition）与配偶选择（mate choice）中所扮演的角色，在物种间及物种种内的变异性均远超此前的认知。在自然环境中，交配竞争发生于配偶搜寻（mate search）过程中，其强度预计会受到潜在配偶数量与同性竞争者数量的调控。
本研究为首个探讨性角色的时间动态变化如何在配偶采样（mate sampling）过程中影响交配竞争与配偶选择的学术工作。本研究选用的模式生物系统为海产鱼类双带缟虾虎鱼（Gobiusculus flavescens），该物种在繁殖季会经历从常规性角色向反转性角色的转变，因此是开展此类研究的绝佳适配体系。
根据性角色理论（sex role theory）的预测，繁殖季早期的求偶行为通常由雄性发起、雌性终止；而繁殖季晚期则呈现完全相反的模式：此时常有多只雌性同时向同一只雄性求偶。进行配偶搜寻的雌性在繁殖季早期访问的雄性个体数量，显著多于繁殖季晚期。
本研究证实，双向配偶选择与交配竞争可对雌雄个体的行为产生深远影响。若要全面理解野外环境中的性选择（sexual selection），未来的研究需充分考量交配竞争与配偶选择的动态本质。