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

O_LISeminal 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. C_LIO_LIWe mostly ignore how abiotic ecological factors regulate SFP expression and transfer. C_LIO_LIHere, we use quantitative proteomics in adult flies from a wild Drosophila melanogaster population to test how exposure to natural temperature variation (20{degrees}C, 24{degrees}C and 28{degrees}C) across two-time scales (48h and 13d), and under either no or high sperm competition risk, interact to shape SFP production and transfer. C_LIO_LIWe show that both production and transfer of SFPs was reduced after long-term (13d) exposure to low (20{degrees}C) and high (28{degrees}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. C_LI