Biology Department, Gonzaga University, Spokane, Washington, United States of America.
PLoS One. 2011 Jan 6;6(1):e15837. doi: 10.1371/journal.pone.0015837.
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.
性选择的 handicap 理论假定，在配偶选择中受到青睐的雄性展示特征会对表现产生重大影响。我们在绿色剑尾鱼（Xiphophorus helleri）中测试了这一假设的一个方面。在这个物种中，雄性尾鳍的下鳍条延伸成一把“剑”，用于吸引潜在的配偶。然而，拥有一把长“剑”可能会增加阻力，从而影响雄性有效游泳的能力。我们通过激发雄性的 C 型逃跑反应来测试这种物种的逃跑性能，这是一种本能的逃跑行为，而雄性的“剑”长度各不相同。然后，我们去除了雄性的“剑”，并重新测试了它们的逃跑性能。我们发现逃跑性能与“剑”的长度之间没有关系，“剑”的去除也不会影响逃跑性能。虽然拥有一把大“剑”可能会引起捕食者的注意，但我们的结果表明，“剑”的大小并不会影响雄性的逃跑性能。
