Experimental evolution on heat tolerance and thermal performance curves under contrasting thermal selection in Drosophila subobscura

Ectotherms can respond to global warming via evolutionary change of their upper thermal limits (CTmax). Thus, the estimation of CTmax and its evolutionary potential is crucial to determine their vulnerability to global warming. However, CTmax estimations depend on the thermal stress intensity, and it is not completely clear whether its evolutionary capacity can be affected. Here, we performed an artificial selection experiment to increase heat tolerance using fast- and slow-ramping selection protocols in Drosophila subobscura. We found that heat tolerance evolved in both selection protocols, exhibiting similar evolutionary change rates and realized heritabilities. Additionally, we estimated the thermal performance curves (TPC) to evaluate correlated responses in TPC. We detected that thermal optimum increased in fast-ramping selection lines, but with a cost at the thermal performance breadth. Whereas, TPC changes were not detected in the slow-ramping selection lines, indicating that the...