Delayed color maturation of a sexual ornament in males of a damselfly: crypsis, female mimicry or both?

Female mimicry by males is a widespread phenomenon in several taxa and may be involved in aggression avoidance or facilitated access to resources. In early developmental stages, female mimicry may be a mechanism involved in signalling sexual maturity or, coupled with strategies related to visual camouflage, may be involved in the avoidance of male-male agonistic interactions. Here, we addressed whether the delayed colour maturation of a sexual ornament in males of Mnesarete pudica damselflies could be a case of crypsis, female mimicry or both. We analysed how the pigmented wing of juvenile males is perceived by conspecifics by contrasting the wing spectra against a Savannah visual background and the wings of both juvenile and sexually mature male and females. Our results based on the modelled visual system of conspecifics suggest that the color maturation of juvenile males could function as both crypsis and female mimicry. We discuss whether these results related to age- and sexual-dichromatism could be a mechanism to avoid unwanted intraspecific interactions or even to deceive territorial and aggressive males. We conclude that the female mimicry and crypsis in juvenile males of M. pudica are a mechanism involved in signalling sexual maturity and avoidance of unwanted intraspecific interactions.

雄性雌性拟态（female mimicry by males）是多个类群中广泛存在的现象，其功能或与躲避攻击、便捷获取资源相关。在发育早期阶段，雄性雌性拟态可能是传递性成熟信号的一种机制；若结合视觉伪装（visual camouflage）策略，还可用于避免雄性间的争斗互动。本研究旨在探究Mnesarete pudica豆娘雄性性装饰器官的体色发育延迟，是否属于隐蔽拟态（crypsis）、雄性雌性拟态，或二者兼具的情况。我们通过将雄性幼体带色素的翅膀光谱与稀树草原视觉背景，以及幼体、性成熟雌雄个体的翅膀光谱进行对比，分析了同种个体对该翅膀的视觉感知情况。基于同种个体视觉系统建模得到的结果显示，雄性幼体的体色成熟过程可同时起到隐蔽拟态与雄性雌性拟态的作用。我们进一步讨论了与年龄和性别双色性（age- and sexual-dichromatism）相关的这些结果，是否可作为避免不必要种内互动，甚至欺骗具有领地意识与攻击性的雄性的机制。最终我们得出结论：M. pudica雄性幼体的雄性雌性拟态与隐蔽拟态，是传递性成熟信号并避免不必要种内互动的一种机制。