Mechanisms of sexual selection operating on body size in the mosquitofish (Gambusia holbrooki)

Publisher Website
Google Scholar
Abstract
Collections in two natural populations of the mosquitofish, Gambusia holbrooki, were made to determine whether the sexes associated nonrandomly based on body size, and laboratory experiments were performed to identify mechanisms that could generate the observed field patterns of association. In both populations larger females were associated with larger males. However, the size distributions of males caught with and without females were not different. Both gravid females and females that had released broods within the previous 24 h spent more time near larger males in laboratory choice experiments. In contrast, males did not discriminate between females on the basis of size or reproductive status in laboratory choice experiments, and males did not attempt relatively more copulations with larger females when one male was allowed to freely interact with two females. Body size differences and aggressive interactions between males did influence the access of males to females, with larger males attempting more copulations with females when two males were allowed to freely interact with one female: aggressive interactions between males were frequent when males differed by < 1.0 mm standard length but were rare when males differed by>5.0 mm standard length. These results indicate that female choice for larger males could contribute to generating the nonrandom associations between the sexes that were observed in these two populations and that interactions between males in the vicinity of females may additionally increase the mating advantages of larger males.

This publication has 0 references indexed in Scilit: