The preference could in turn promote the evolution of female ornaments that reflect fecundity.Ī potential example of a sexually ornamented female is the common glow-worm ( Lampyris noctiluca, Lampyridae), a nocturnal capital breeder. If females vary significantly in fecundity and mating is costly or mate encounter rate high, males would benefit from expressing a preference for a trait that indicates fecundity. Even though there is a trade-off between fecundity and mate attraction, the evolution of fecundity-indicating ornaments may be owing to an inability of males to assess female size and fecundity directly.

This is surprising, given that males can be choosy and could act on female ornamentation. įew studies have, however, tested the underlying reasons for the rarity of female ornaments in a sexual selection context. Female ornaments in a sexual selection context are more common when the species is sex-role reversed, or when the ornament is a consequence of a genetic correlation with male ornamentation. Moreover, fecundity is often correlated with body or abdomen size and the use of ornaments to advertise fecundity may then be superfluous. This is because investment into ornaments decreases fitness by taking resources away from fecundity, creating a trade-off between ornamentation and fecundity. When they occur, they are often linked to resource competition or high male investment into offspring rather than to sexual selection. those in which stored resources are invested in reproduction) when females vary significantly in fecundity and this variation cannot be assessed directly by males.įemale ornaments are comparatively rare in nature. These results indicate that female ornamentation may evolve in capital breeders (i.e. 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. Thus, the glow emitted by females is a reliable sexual signal of female fecundity. In support of this, we found brightness to correlate with female fecundity, and males to prefer brighter dummy females. Here, we investigated if the female ornament of the glow-worm is a signal of fecundity used in male mate choice. However, little is known about the factors that promote the evolution of female ornaments in a sexual selection context. The glow-worm ( Lampyris noctiluca) is an exception where wingless females glow to attract males that fly in search of females. Females, by contrast, rarely produce ornaments. In many species, males rely on sexual ornaments to attract females.

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