Current rising temperatures are threatening biodiversity. It is therefore crucial to understand how climate change impacts male and female fertility and whether evolutionary responses can help in coping with heat stress. We use experimental evolution to study male and female fertility during real-time evolution of two historically differentiated populations of Drosophila subobscura under different thermal selection regimes for 23 generations. We aim to (1) tease apart sex-specific differences in fertility after exposure to warming conditions during development, (2) test whether thermal selection can enhance fertility under thermal stress, and (3) address the role of historically distinct genetic backgrounds. Contrary to expectations, heat stress during development had a higher negative impact on female fertility than on male fertility. We did not find clear evidence for enhanced fertility in males or females evolving under warming conditions. Population history had a clear impact on fertility response under thermal stress, particularly in males with those from lower latitudes presenting better performance than their higher latitude counterparts. We show that the impact of thermal stress on fertility varies between traits, sexes and genetic backgrounds. Incorporating these several levels of variation is crucial for a deeper understanding of how fertility evolves under climate change.

This dataset includes the raw data for the article accepted for publication in Evolution (EVO-23-0043): "Sex and population differences underlie variation in reproductive success in a warming environment.” Data correspond to a phenotypic assay performed on experimental populations after 23 generations of evolution in different thermal selection regimes. Assay included populations from 2 thermal selection regimes (warming vs controls, each three fold replicated). Adult reproductive performance (Fecundity, productivity and juvenile viability) under warming conditions (peak temperature of 29.4ºC) was assessed for couples (1 male + 1 female) of the different experimental populations in which either the male, the female or both were exposed to those same warming conditions during the developmental stage. Raw data are the individual data from each assayed couple from a given experimental population. Please see the accompanying README.md file for details on data description and structure.