Extreme repeated mating as a counter-adaptation to sexual conflict?

ABSTRACT

The Australian scaly cricket, Ornebius aperta, can copulate over 50 times with the same partner; the benefits of such extreme repeated copulation are unclear. We support the hypothesis that repeated copulation increases insemination success, as the number of sperm transferred increases with each spermatophore. This probably increases paternity for males, as on average a female mates with over 40 males. Despite intense sperm competition each ejaculate has only a few hundred sperm, orders of magnitude less than in related crickets. We show that all sperm are transferred from each spermatophore in the few seconds before a female removes and eats it. Repeated copulation increases effective copulation duration while a small ejaculate ensures that this strategy is not excessively costly. Thus repeated copulation in these crickets may have arisen as a counter-adaptation to female-imposed limits on copulation.