Data from: I’m sexy and I glow it: female ornamentation in a nocturnal capital breeder

In many species, males rely on sexual ornaments to attract females. Females, by contrast, rarely produce ornaments. The glow-worm (Lampyris noctiluca) is an exception where wingless females glow to attract males that fly in search of females. However, little is known about the factors that promote the evolution of female ornaments in a sexual selection context. Here, we investigated if the female ornament of the glow-worm is a signal of fecundity used in male mate choice. In support of this, we found brightness to correlate with female fecundity, and males to prefer brighter dummy females. Thus, the glow emitted by females is a reliable sexual signal of female fecundity. It is likely that male preference for the fecundity-indicating ornament has evolved because of large variation among females in fecundity, and because nocturnal males cannot directly assess female size and fecundity. These results indicate that female ornamentation may evolve in capital breeders (i.e. those in which stored resources are invested in reproduction) when females vary significantly in fecundity and this variation cannot be assessed directly by males.

在诸多物种中，雄性通常依赖性装饰特征来吸引雌性，而雌性则极少演化出此类装饰。光萤（glow-worm, Lampyris noctiluca）则是特例：其无翅雌性通过发光来吸引前来寻觅雌性的飞行雄性。然而，目前学界对性选择背景下驱动雌性装饰特征演化的相关因素仍知之甚少。

本研究以光萤为研究对象，旨在探究其雌性发光装饰是否为雄性择偶过程中可感知的繁殖力信号。研究结果支持这一假说：雌性发光亮度与自身繁殖力呈显著正相关，且雄性更偏好发光亮度更高的雌性模拟个体。由此可见，雌性发出的萤光可作为反映其繁殖力的可靠性选择信号。

雄性对这类传递繁殖力信息的装饰特征的偏好，其演化可能源于两大关键因素：一是雌性个体间繁殖力差异显著，二是夜行性雄性无法直接评估雌性的体型与繁殖力水平。本研究结果表明，在「资本繁育者（capital breeder，即所有繁殖所需资源均来自体内储存储备的类群）」中，当雌性个体繁殖力差异显著且雄性无法直接评估该差异时，雌性装饰特征便有可能得以演化。