Behavioral and TRPA1 Heat Sensitivities in Three Sympatric Cuban Anolis Lizards

I would like to introduce our recently published paper on Comparison of Behavioral and TRPA1 heat sensitivities in Cuban Anolis lizards. In Cuba, three sympatric species of Anolis lizards (Anolis allogus, A. homolechis, and A. sagrei) inhabit different thermal microhabitats (above). Different thermal habitats, that is shade, edges of forests and cleared forests, are occupied by A. allogus, A. homolechis and A. sagrei, respectively. Anolis allogus is non-heliothermic, while A. homolechis and A. sagrei are heliothermic species. Our previous study found that these species showed distinct gene expression patterns in response to temperature stimuli, suggesting the genetically distinct thermal physiology among species (Akashi et al. 2016. Mol.Ecol.).

For lizards, heat avoidance behavior is crucial for limiting their body temperatures within thermally safe margins. We predict that the temperature that elicits heat avoidance behavior would differ between these three Anolis species, and the differences might be related to different heat sensors among the species. Organisms perceive various temperatures via biological temperature sensors, such as thermosensitive transient receptor potential ion channels (thermo-TRPs). Among known thermo-TRPs, transient receptor potential ion channel ankyrin 1 (TRPA1) in non-mammalian species has been reportedly heat sensitive (Saito et al. 2012).

In our paper, we first conducted behavioral experiments to analyze the temperatures at which the three Anolis species escape from heat source (i.e., hotplate; Fig. 1) to examine whether the Anolis species inhabiting locally distinct thermal habitats diverge their thermal tolerances.

Then, for each of the three species, we isolated cDNA encoding of TRPA1, and performed electrophysiological analysis to quantify activation temperature of Anolis TRPA1. We found that temperatures triggering behavioral and TRPA1 responses were significantly lower for the shade-dwelling, non-heliothermic species (A. allogus) than for sun-dwelling heliothermic species (A. homolechis and A. sagrei).

The ambient temperature of shade habitats where A. allogus occurs stays relatively cool compared to that of open habitats where A. homolechis and A. sagrei occur and bask. The high temperature thresholds of A. homolechis and A. sagrei may reflect their heat tolerances that would benefit these species to inhabit the open habitats.

Akashi, H., S. Saito, A. Cádiz , T. Makino, M .Tominaga, M. Kawata. (2018) Comparisons of behavioral and TRPA1 heat sensitivities in three sympatric Cuban Anolis lizards. Molecular Ecology https://doi.org/10.1111/mec.14572