Our understanding of sexual selection has greatly improved during the last decades. The focus is no longer solely on males, but also on how female competition and male mate choice shape ornamentation and other sexually selected traits in females. At the same time, the focus has shifted from documenting sexual selection to exploring variation and spatiotemporal dynamics of sexual selection, and their evolutionary consequences. Here, I review insights from a model system with exceptionally dynamic sexual selection, the two-spotted goby fish Gobiusculus flavescens. The species displays a complete reversal of sex roles over a 3-month breeding season. The reversal is driven by a dramatic change in the operational sex ratio, which is heavily male-biased at the start of the season and heavily female-biased late in the season. Early in the season, breeding-ready males outnumber mature females, causing males to be highly competitive, and leading to sexual selection on males. Late in the season, mating-ready females are in excess, engage more in courtship and aggression than males, and rarely reject mating opportunities. With typically many females simultaneously courting available males late in the season, males become selective and prefer more colorful females. This variable sexual selection regime likely explains why both male and female G. flavescens have ornamental colors. The G. flavescens model system reveals that sexual behavior and sexual selection can be astonishingly dynamic in response to short-term fluctuations in mating competition. Future work should explore whether sexual selection is equally dynamic on a spatial scale, and related spatiotemporal dynamics.
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机译:在过去的几十年中,我们对性选择的了解大大提高了。重点不仅限于男性,还包括女性的竞争和男性伴侣的选择如何塑造女性的装饰和其他性选择的特征。同时,重点已从记录性选择转移到探索性选择的变异和时空动态及其演变结果。在这里,我回顾了来自具有异常动态性选择的模型系统的见解,即两点斑的虾虎鱼Gobiusculus flavescens。在三个月的繁殖季节中,该物种显示出完全相反的性别角色。业务性别比的巨大变化推动了这种逆转,该性别比在本赛季开始时严重偏重男性,在本赛季后期偏重女性偏重。在本赛季初期,可育种的雄性比成年雌性多,导致雄性竞争激烈,并导致雄性选择。在赛季后期,准备交配的雌性数量过多,比雄性更多地从事求偶和侵略,很少拒绝交配机会。通常情况下,许多雌性会在本季后期同时求助于可用的雄性,因此雄性会变得有选择性,并喜欢颜色更丰富的雌性。这种可变的性选择机制可能解释了为什么雄性和雌性黄萎病菌均具有装饰色。 G. flavescens模型系统表明,性行为和性选择对交配竞争中的短期波动具有惊人的动态。未来的工作应该探讨性选择在空间尺度上是否具有同等的动态性,以及相关的时空动态性。
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