Chilling out or heating up? Thermal plasticity of seminal fluid proteins in Drosophila melanogaster

Seminal fluid proteins (SFPs) play crucial roles in reproduction by shaping female post-mating physiology and behaviour, male sperm competition, and sexual conflict between the sexes.

We mostly ignore how abiotic ecological factors regulate SFP expression and transfer.

Here, we use quantitative proteomics in adult flies from a wild Drosophila melanogaster population to test how exposure to natural temperature variation (20°C, 24°C and 28°C) across two-time scales (48h and 13d), and under either no or high sperm competition risk, interact to shape SFP production and transfer.

We show that both production and transfer of SFPs was reduced after long-term (13d) exposure to low (20°C) and high (28°C) temperatures, including in key proteins (sex peptide and ovulin networks) mediating female post-copulatory responses, sperm competition and sexual conflict. Our results show that natural temperature fluctuations can have a strong effect on SFP production and transfer, and thus on post-copulatory sexual selection dynamics.