Short-term captivity does not affect immediate voluntary thermal maximum of a neotropical pitviper: Implications for behavioral thermoregulation.

Abstract

Ectotherms depend on temperature to maintain their physiological functions and through behavioral changes, they can avoid overheating in their habitats. The voluntary thermal maximum (VTMax ) represents the maximum temperature tolerated by individuals before actively moving to a colder place. However, if and how VTMax might change after capture and in captivity remains understudied. We investigate if measurements taken in captivity are a good proxy for thermal tolerance of wild individuals. Asthermal history has been shown to affect behavioral response and physiological parameters, herein we hypothesized that VTMax of the neotropical viper Bothrops pauloensis varies throughout the captivity period. We measured the VTMax of individuals immediately after capture and in three trials during a short-term period in captivity. Measurements were done by recording their body temperature at which they exited a heating box experimental setup. In contrastto our hypothesis, the VTMax was not significantly affected by time in captivity but there was interindividual variation. There were also no significant differences between field and captivity measurements, in spite of the small effect size. Our results indicate that the VTMax of this snake population is not affected by a short-term captivity period. Furthermore, an invariant VTMax might indicate low phenotypic plasticity, as individuals do not appear to adjust their tolerance to short-term exposure to higher temperaturesand potential vulnerability to threats such as global warming. We expect that our results can contribute to understanding the effect of captivity on thermal tolerance in neotropical squamates, allowing for insights into their thermal physiology and ecology.