Bolder guppies do not have more mating partners, yet sire more offspring

Intra-individual stable but inter-individually variable behaviours, i.e. personalities, are commonly reported across diverse animal groups, yet the reasons for their maintenance remain controversial. Therefore, studying fitness consequences of personality traits is necessary to discriminate between alternative explanations.

Here, I measured boldness, a highly repeatable personality trait, and reproductive success in male guppies, Poecilia reticulata. I found that bolder males had higher reproductive success than their shyer conspecifics and they sired offspring with females who had larger clutches.

This result provides direct evidence for fitness consequences of boldness in the guppy. It suggests that the effect may be driven by bolder males mating with more fecund females.