Predator exposure leads to a short-term reversal in female mate preferences in the green swordtail, Xiphophorus helleri

Abstract

Ecological factors have been shown to influence mate choice, resulting in the alteration, loss, and even reversal of mate preference. One such factor is the presence of a predator during mate choice, because females that associate with conspicuous males may experience a higher risk of mortality in high-predation environments. Despite accumulating studies demonstrating predator-induced plasticity in female preferences, it is still unclear how these changes affect the strength or direction of selection. Additionally, even though the temporal dynamics of female plasticity (and the cues that induce it) have important implications for the evolutionary dynamics of sexual selection, little is known about this temporal aspect of mate preferences. Here, we addressed this gap using female green swordtails, Xiphophorus helleri, which typically prefer males with long swords. We first examined mate preference in the control (no predator) treatment and asked whether the preference changes immediately following predator exposure. In this experiment, females preferred long-sworded males in the control treatment and short-sworded males in the predator treatment. This suggests that natural and sexual selection may act synergistically in high-predation environments, with both favoring this shorter sword length. We then asked whether females still prefer short-sworded males 24 h after exposure to the predator. Our results demonstrate that the reversal in female mate preference does not persist after 24 h, suggesting that the effect of predators on mating behavior may be more complex than previously thought. Predator encounter rate may thus have the potential to influence sexual selection dynamics in natural populations.