The cost of the sword: escape performance in male swordtails.
The handicap theory of sexual selection posits that male display traits that are favored in mate choice come at a significant cost to performance. We tested one facet of this hypothesis in the green swordtail (Xiphophorus helleri). In this species, the lower ray of male caudal fin is extended into a 'sword', which serves to attract potential mates. However, bearing a long sword may increase drag and thus compromise a male's ability to swim effectively. We tested escape performance in this species by eliciting C-start escape responses, an instinctive escape behavior, in males with various sword lengths. We then removed males' swords and retested escape performance. We found no relationship between escape performance and sword length and no effect of sword removal on escape performance. While having a large sword may attract a predator's attention, our results suggest that sword size does not compromise a male's escape performance.
Biology Department, Gonzaga University, Spokane, Washington, United States of America.
Alex
A
Baumgartner
Seth
S
Coleman
Brook
B
Swanson
D000818:Animals; D005075:Biological Evolution; D003532:Cyprinodontiformes / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology*; D004924:Escape Reaction; D008297:Male; D052586:Mating Preference, Animal / Q000502:physiology*; D012641:Selection, Genetic; D012727:Sex Characteristics; D012726:Sexual Behavior, Animal / Q000502:physiology*
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