Felix P. Leiva , Mauro Santos, Edwin J Niklitschek, Enrico L. Rezende, Wilco C.E.P. Verberk

 The assessment of thermal tolerance holds significant importance in predicting the physiological responses of ectotherms, particularly in elucidating their capacity for evolutionary adaptation in the context of global warming. Current approaches to assessing thermal tolerance have limitations that can lead to misleading results, especially with regard to the heritability of thermal limits. In this study, we examined twenty isogenic lines of Drosophila melanogaster from the DGRP panel to characterize their thermal death time (TDT) curves, which account for the duration and intensity of heat stress. Furthermore, we examined the extent of genetic variation in the intercept and slope of the linear TDT curves, which are labelled as CTmax and thermal sensitivity z. Our analysis revealed evidence of heritable variation in each of the two parameters. Furthermore, simulations of the evolutionary consequences of selection on either CTmax or z indicate that selection on one parameter induces changes in the other parameter as a correlated response. We conclude that the evolution of thermosensitive or thermotolerant strategies is better achieved by directional selection to decrease or increase CTmax, which may aid in mitigating the effects of global warming on ectotherms.