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Interacting color and behavior responses to predation risk and ultraviolet radiation in the salamander species Ambystoma barbouri and Ambystoma texanum.
Garcia, Tiffany1, Sih, Andrew1, 1
ABSTRACT- The effect of multiple, conflicting selection pressures on the coevolution of multiple, interacting traits is an understudied topic in evolutionary ecology. Integrative studies on multiple traits, such as color and behavior, (i.e. refuge use, color-specific habitat choice) under multiple environmental pressures can reveal important tradeoffs and constraints on trait selection. We examined larval body color and behavioral responses to ultraviolet radiation and predation risk in two salamander species, Ambystoma barbouri and A. texanum that differ in habitat and selection pressures. We found that both species increased refuge use in response to both predatory fish chemical cues and ultraviolet radiation. We also found that in the absence of refuge, ambient UV exposure resulted in a significant color response; both species darkened in body color. The two species differed, however, when given a choice between behavioral versus color change avoidance strategies in response to predation risk and UV. A. barbouri responded to both predation risk and UV radiation with increased refuge use, and when given a choice between multiple background colors, preferred darker substrates. A. barbouri exhibited high plasticity in body coloration with rapid habituation to new background colors. In contrast, A. texanum visually assessed how well body color cryptically matched the background, and adjusted location, not color, accordingly. Plastic color change in A. texanum is relatively limited; refuge use was thus their preferred response to predation risk when cryptic backgrounds are not available.
KEY WORDS: Ambystoma, Predation , Ultraviolet, color