Male spacing and female choice in a fiddler crab

The aggregation of courting males is widespread among animal taxa, yet we do not understand why males congregate and therefore intensify local competition for female attention. The most commonly invoked theoretical explanation is that females preferentially approach clustered males due to the many benefits they would gain, and clustered males would therefore have higher mating success. However, although theoretical explanations of aggregation formation are well-advanced, empirical studies are scarce, especially in invertebrates. In fact, there is little evidence that females do prefer to approach clustered over spaced displayers. Here we address this question by using robotic crabs to test female preferences in fiddler crabs (a visually displaying species) and show that female do not preferentially approach clustered males. We suggest that if this pattern is more widespread, the most commonly invoked explanation of courting aggregations is of limited use. We offer explanations for the s...求偶雄性的集群行为在多个动物类群中广泛存在，但目前学界尚未明确雄性为何会聚集，进而加剧局部范围内争夺雌性关注的竞争强度。目前最常被援引的理论解释认为，雌性会优先趋近集群的雄性，因其可从中获得多重收益，而集群雄性的交配成功率也会因此更高。然而，尽管关于集群形成的理论解释已较为完善，但相关实证研究却十分匮乏，针对无脊椎动物的相关研究尤甚。事实上，几乎没有证据表明雌性确实更倾向于趋近集群的雄性，而非分散开来的求偶展示个体。本研究以招潮蟹（一种依靠视觉进行求偶展示的物种）为研究对象，利用机器蟹开展实验以检验雌性的择偶偏好，结果发现雌性并不会优先趋近集群的雄性。我们提出，若该研究结果所反映的模式具有更广泛的普适性，那么目前最常被援引的求偶集群理论解释的适用范围将十分有限。我们将就该现象的成因提供相关解释……