ABSTRACT
Invasive species have emerged as a significant problem in the age of anthropogenic change. Behavior can be key to invasive species success and is strongly affected by temperature. Therefore, knowledge of the temperature dependence of behavior is likely critical to understand invasive species dynamics and their interactions with native species. In this study, we tested for differences in thermal preference plasticity and temperature-dependent activity levels in a pair of congeneric lizards found in the United States: the invasive Anolis sagrei and the native A. carolinensis. We predicted that A. sagrei would demonstrate greater thermal preference plasticity and would utilize a higher and/or wider range of activity temperatures than A. carolinensis. Both would point to plasticity allowing A. sagrei to behaviorally exploiting thermal conditions that A. carolinensis cannot. We found that both species exhibited plasticity in thermal preference, but in opposite directions: preferred temperatures of A. carolinensis increased with acclimation temperature, while those of A. sagrei decreased. As a result, which species had a higher thermal preference changed with acclimation conditions. We saw no difference in overall field activity rates between the species, but that A. sagrei did tend to be active over a broader range of body temperatures. In sum, we found little evidence that differences in thermal preference plasticity between the species allow A. sagrei to remain active at a higher or broader temperature range than A. carolinensis. Nonetheless, the thermal preference data suggest complementary thermal preferences between the species that could promote microclimatic partitioning, though more work is required to test this idea.
