Basal cold but not heat tolerance constrains plasticity among Drosophila species (Diptera: Drosophilidae)

Thermal tolerance and its plasticity are important for understanding ectotherm responses to climate change. However, it is unclear whether plasticity is traded off at the expense of basal thermal tolerance and if plasticity is subject to phylogenetic constraints. Here, we investigated associations between basal thermal tolerance and acute plasticity thereof in laboratory-reared adult males of eighteen Drosophila species at low and high temperatures. We determined the high and low temperatures where 90 % of flies are killed (ULT90 and LLT90 respectively) and also the magnitude of plasticity of acute thermal pre-treatments (i.e. rapid cold- and heat-hardening) using a standardized, species-specific approach for induction of hardening responses. Regression analyses of survival variation were conducted in ordinary and phylogenetically-informed approaches. Low temperature pre-treatments significantly improved LLT90 in all species tested except for D. pseudoobscura, D. mojavensis and D. borea...