Male mate choice in the annual fish Austrolebias reicherti (Cyprinodontiformes: Rivulidae): when size matters

While the importance of male mate choice is increasingly recognized, it continues to be an understudied aspect of sexual selection. Here, the effect of female body size on male mate choice was evaluated in the annual killifish Austrolebias reicherti, a species with marked sexual dimorphism in which males are more conspicuous than females. In dual-choice mate choice trials with unequal sized females we found that males spent significantly more time with larger females. Furthermore, larger females spawned more and larger eggs when spawning was allowed in non-choice trials. Therefore, male selection is probably attributable to the higher reproductive success of larger females. To our knowledge, this is the first study that provides evidence of both male mate choice in annual fishes and its possible fitness advantages. The implications of male mate choice for sexual selection in these fish highlight the need for further studies.