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.

近年研究表明，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，无论在物种间还是物种内部，均比此前学界认知更为多变。在自然环境中，交配竞争发生于配偶搜寻（mate search）过程中，且理论上受潜在配偶数量与同性竞争者数量调控。本研究首次探讨了性角色（sex roles）的时间动态变化，如何在配偶取样（mate sampling）过程中影响交配竞争与配偶选择。本研究选用的模式生物（model system）为海洋鱼类细鳍虎鱼（Gobiusculus flavescens），其在繁殖季内的性角色会从传统模式转变为反转模式，因此具备独特的研究适用性。正如性角色理论所预测的那样，繁殖季早期的求偶行为通常由雄性发起、雌性终止；而繁殖季后期则呈现完全相反的模式，此时往往有多只雌性同时向同一只雄性求偶。繁殖季早期进行配偶搜寻的雌性会接触更多雄性个体，这一数量在繁殖季后期有所减少。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）机制，未来研究需充分考量交配竞争与配偶选择的动态属性。