Cross-tolerance evolution is driven by selection on heat tolerance in Drosophila subobscura

Abstract

The evolution of heat tolerance is a crucial mechanism for the adaptive response to global warming, but it depends on the genetic variance carried by populations and on the intensity of thermal stress in nature. Selection experiments for heat tolerance have been key to understanding the evolution of heat tolerance, but the effect of variable heat stress intensity on the correlated responses of resistance traits has not been investigated. Here, the effects of heat intensity selection (fast and slow ramping temperatures) for increasing knockdown temperature in Drosophila subobscura were evaluated on knockdown time at different stress temperatures (35, 36, 37 and 38 °C), thermal death time (TDT) curves, desiccation and starvation resistance. Correlated evolution was found for these four resistance traits in D. subobscura, indicating that the evolutionary response to tolerate higher temperatures also confers the ability to tolerate other stresses such as desiccation and starvation. However, these correlated responses were dependent on the intensity of thermal selection and on sex, which may limit our ability to generalize these results to natural scenarios. Nevertheless, this study confirms the value of the experimental evolutionary approach for exploring and understanding the adaptive responses of natural populations to global warming.

Competing Interest Statement

The authors have declared no competing interest.

Footnotes

* The context of the manuscript has been changed according to the comments of the editor and reviewers. Table 2 has been removed. Figure 2 has been modified

* https://doi.org/10.6084/m9.figshare.24085107