Beating the heat: a lowland tropical lizard expresses heat shock protein networks in response to acute thermal stress.

Ectothermic species in lowland tropical forests have evolved in historically stable climates, leading to the prediction that transcriptomic and phenotypic plasticity do not play major roles in their responses to changes in environmental temperature. However, these species are often thermoconformers and are therefore exposed to short-term temporal fluctuations in temperature. Hence, transcriptomic plasticity in tropical forest ectotherms might replace behavioral thermoregulation as a mechanism to buffer against thermal stress. In particular, upregulatation of heat shock proteins can occur during thermal stress is a range of organisms. However, while many studies have explored gene expression plasticity in response to heat stress in model organisms, little is known about transcriptomic plasticity in the tropical, non-model species that will be the most impacted by climate change. We studied the effects of moderate and severe acute heat stress events in the Panamanian slender anole (Anolis apletophallus) to gain insight into a mechanism that might allow tropical ectotherms to withstand the heat waves that are likely to rise in frequency over the coming decades under anthropogenic climate change. We found that multiple genes were upregulated across several heat shock protein networks in three tissues, and the magnitude of the expression response was similar irrespective of whether heat stress was moderate or severe. Overall, our results indicate a potentially crucial role for heat shock protein networks in the ability of tropical ectotherms to resist the negative effects of rising temperatures.