Fight outcome is predicted by jumping performance and head size but not metabolic rate in male fall field crickets

The outcome of male-male contests is a major determinant of reproductive success in many species. Because of this, traits that are associated with winning fights are often more pronounced in winner males than in loser males. Here, we examined a variety of morphological, physiological and performance traits that may predict the outcome of contests between male fall field crickets (Gryllus pennsylvanicus). We staged contests between size-matched male crickets and also collected data on jumping performance, standard and maximum metabolic rate, and head and hindlimb morphological traits. Though some of these traits have been examined previously, others have not been examined in the context of male-male competition and the full set of traits have not been measured on the same individuals. Our results indicate that winners, as compared with losers, had significantly greater head size, maxilla size, jump performance (distance, takeoff velocity, total kinetic energy and mass-specific power) and marginally greater hindlimb muscle mass. We found no differences between winners and losers for standard or maximum metabolic rate or factorial metabolic scope. This integrative dataset contributes to a broader understanding of sexual selection in this species.