Cryptic male mate choice for high-quality females reduces male postcopulatory success in future matings.

Cryptic male mate choice occurs when males differentially allocate resources to females during or after copulation. When male resources are limited, males may benefit by strategically allocating more resources toward higher-quality females. In the fruit fly, Drosophila melanogaster, males mate for longer and may transfer more sperm and more seminal proteins when they mate with larger females compared with smaller females. It is unclear, however, whether this increased investment in large females has any impact on the males' later matings. We mated D. melanogaster males sequentially to females of large or small body size in all possible combinations to test whether cryptic male mate choice for large females is costly to the males' subsequent matings. Second matings were shorter for males compared with their first matings, but there were no differences in fecundity between females mated first or second by a male. Interestingly, male success at defensive sperm competition declined between his first and second matings only when his first mating had been with a large female. This suggests that the higher initial investment in large females reduced male postcopulatory success in their subsequent matings. Cryptic male mate choice may carry underappreciated costs to males that could limit their reproductive potential.