LB 4-22 - Antipredator behavior and microhabitat preferences differ between the sexes in Anolis aquaticus

Background/Question/Methods:

Antipredator behavior, while necessary for survival, often incurs costs for the individual performing the behavior. This is especially true for ectotherms that escape to microhabitats where maintaining optimal body temperatures is not possible, such as aquatic habitats. Water anoles (Anolis aquaticus) employ a unique antipredator behavior involving land-to-water escape routes. We predicted that, as an ectotherm, A. aquaticus faces a thermal tradeoff as a result of this antipredator behavior and that decisions related to diving (e.g., dive duration) may be influenced by sex. We also predicted that the sexes would differ with respect to microhabitat preferences, such as perch location, dissolved oxygen concentration, water flow, and temperature. This study was conducted at Las Cruces Biological Station in Coto Brus, Costa Rica.

Results/Conclusions:

As predicted, body temperature decreased after dives, with significant differences between the sexes. Overall, males maintained higher body temperatures than females, and their dive durations were shorter. We also found that A. aquaticus overall preferred terrestrial microhabitats close to water with relatively higher dissolved oxygen concentrations, and that males preferred higher perches that were close to water with greater flow. As a whole, these findings suggest fundamental differences between the sexes regarding antipredator behavior, with males undertaking shorter dives and favoring microhabitats that optimize the dynamic between energy expenditure and mating success.