Heat tolerance lability in Caribbean lizards

Nicole Frances Angeli (1) , Lee Austin Fitzgerald (2)

1 Texas A&M University, 210 Nagle Hall, Texas, 77840,  nangeli@tamu.edu, @Auratus_Nicole

2 Texas A&M University, 210 Nagle Hall, Texas USA, 77840

Species may respond to climate change through adaptation, phenotypic plasticity, or the cumulative ability of individuals to acclimatize. Species with limited capacity to exploit changing environments should decline more often than species with the capacity to adjust. These two responses, persistence and decline, may be buffered by life history and physiological traits, or other mechanisms like behavior. In accordance with the climatic variability hypothesis, we predicted that more widespread species would have more capacity to respond to extreme heat under experimental conditions and in predicted climate scenarios. Ground lizards (Ameiva spp.) are widely distributed habitat generalists that live in warm heterogeneous environments. We measured morphological and physiological traits at 17 geographically isolated sites across the Puerto Rican Bank in the Caribbean Sea for more than 120 individuals among the 3 species of ground lizards in the Exsul Group: the widespread and persistent Ameiva exsul, the coastal forest restricted and declining Ameiva wetmorei, and the offshore island restricted and critically endangered Ameiva polops. Experimentally, population means for the widespread Ameiva exsul as well as the range-restricted Ameiva species (wetmorei and polops) diverged for heat tolerance and preferred temperature. Demonstrating population-level differences in heat tolerance within species restricted to single types of macrohabitat was contrary to our predictions. We speculate that microhabitat refugia and evolutionary history may be important drivers of thermal trait lability. We calculate the warming tolerance (heat tolerance ~ climate scenarios) to draw conclusions about whether adaptive capacity is a potential buffering agent to consider when predicting species responses to global warming.