Temperature and ontogenetic effects on color change in the larval salamander species Ambystoma barbouri and Ambystoma texanum

Abstract

Temperature has been shown to affect body color in several species of amphibians. The interaction between color and temperature may also change over larval ontogeny, perhaps because of age-related or seasonal changes in selection pressures on color. We quantified the effects of temperature on the color of the salamander sister species Ambystoma barbouri and Ambystoma texanum over larval ontogeny. We found that early-stage larvae responded to cold temperatures with a dark color relative to that of the warm temperature response. Both species then exhibited an ontogenetic shift in larval color, with larvae becoming lighter with age. Interestingly, older larvae showed decreased plasticity in color change to temperature when compared with younger stages. Older A. barbouri larvae showed no color response to the two temperature treatments, whereas older A. texanum larvae exhibited a reversal in the direction of color change, with cold temperatures inducing a lighter color relative to warm temperatures. We suggest that the overall pattern of color change (a plastic color response to temperature for young larvae, a progressive lightening of larvae over development, and an apparent loss of color plasticity to temperature over ontogeny) can be plausibly explained by seasonal changes in environmental factors (temperature, ultraviolet radiation) selecting for body color.

Color change and color-dependent behavior in response to predation risk in the salamander sister species Ambystoma barbouri and Ambystoma texanum

“…On average, A. texanum larvae are significantly lighter in color than their sister species A. barbouri (Garcia et al 2003). Interestingly, this contrasts sharply with the natural substrate in their respective habitats.…”

“…Thus, the stream species probably experiences greater selection to cope with high levels of potentially damaging UVR. Amphibians can respond to UVR with behavioral avoidance and color change (Belden et al 2000;Garcia et al 2003b): the same sorts of responses shown to predators.…”

“…Both species become darker when exposed to UVR (Garcia et al 2003b). Also, both species tend to be lighter at night than in the day (Garcia and Sih, unpublished data), due perhaps to the absence of UVR at night, coupled with a possible energetic cost of maintaining a dark color.…”

“…We studied the above issues in a pair of sister species that differ in color and behavioral response to predators. Larvae of the streamside salamander, Ambystoma barbouri, are significantly darker than their sister species, the smallmouth salamander, A. texanum (Garcia et al 2003). A. barbouri also show stronger antipredator responses to predatory fish cues than A. texanum Sih et al 2000).…”

A growth cost of experimentally induced conspicuous coloration in first-year collared lizard males

“…These sometimes include natural selection for effective thermoregulation (Christian 1996;Bittner et al 2002;Garcia et al 2003) and interactions with both predators and prey (Grether and Grey 1996). Sexual selection may also favor coloration that functions in social signaling (Cooper and Greenberg 1992;Whiting et al 2003).…”