Comparisons of behavioural and TRPA1 heat sensitivities in three sympatric Cuban <italic>Anolis</italic> lizards.

Abstract: Thermal tolerances of organisms play a role in defining geographic ranges and occurrence of species. In Cuba, three sympatric species of <italic>Anolis</italic> lizards (<italic>Anolis allogus</italic>,<italic> Anolis homolechis</italic> and <italic>Anolis sagrei</italic>) inhabit different thermal microhabitats. A previous study found that these species showed distinct gene expression patterns in response to temperature stimuli, suggesting the genetically distinct thermal physiology among species. To investigate whether the <italic>Anolis</italic> species inhabiting locally distinct thermal habitats diverge their thermal tolerances, we first conducted behavioural experiments to analyse the temperatures at which the three <italic>Anolis</italic> species escape from heat source. Then, for each of the three species, we isolated cDNA encoding a putative molecular heat sensor, transient receptor potential ion channel ankyrin 1 (TRPA1), which has been suggested to play a role on eliciting behavioural responses to heat stimuli. We performed electrophysiological analysis to quantify activation temperature of <italic>Anolis</italic> TRPA1 to see whether the pattern of divergence in TRPA1 responses is congruent with that of divergence in behavioural responses. We found that temperatures triggering behavioural and TRPA1 responses were significantly lower for shade‐dwelling species (<italic>A. allogus</italic>) than for sun‐dwelling species (<italic>A. homolechis</italic> and <italic>A. sagrei</italic>). The ambient temperature of shade habitats where <italic>A. allogus</italic> occurs stays relatively cool compared to that of open habitats where <italic>A. homolechis</italic> and <italic>A. sagrei</italic> occur and bask. The high temperature thresholds of <italic>A. homolechis</italic> and <italic>A. sagrei</italic> may reflect their heat tolerances that would benefit these species to inhabit the open habitats. [ABSTRACT FROM AUTHOR]