The effect of sire dominance and aggression on fitness measures in a field cricket (Gryllus assimilis)

• We tested whether mating with dominant male field crickets affects female fitness.
• Females mated to dominant males did not have higher fitness.
• Female fitness was not increased by observing male–male fights.
• Females produced larger adult offspring when they mated with aggressive males.

Theory stipulates that females should prefer to mate with higher-quality mates to maximize their fitness. As such, traits that females prefer should be honest indicators of male quality. Dominant males are often higher quality, and mating with dominant males may confer indirect fitness benefits to females. Male Jamaican field crickets, Gryllus assimilis, fight more aggressively in front of a female audience than when there is no audience present. Males may increase their aggression because females prefer to mate with males who they have seen win a fight. To test this hypothesis we first allowed females to observe (treatment) or not observe (control) fights and then mated females to either fight winners or losers. We then assessed the following fitness measures: number of eggs oviposited, egg viability, offspring viability and offspring size at adulthood. Neither male fight victory status nor female observer/nonobserver status influenced any of the aforementioned female fitness measures; however, the aggressiveness level of the fight did. Females that mated with males that had participated in more aggressive fights produced offspring that were larger at adulthood. Given that females find larger males more attractive, and larger females oviposit more eggs, these larger offspring may experience greater reproductive success and as a result provide females with indirect fitness benefits.