Infidelity encourages faster sperm
Sex tricks: A cichlid Neolamprologus leleupi swimming in the southern shores of Africa's Lake Tanganyika. Credit: Sigal Balshine
LONDON: Promiscuous behaviour in female cichlid fish may have caused males to evolve speedier, bigger sperm, according to a new study.
When females shop around for sexual partners, sometimes mating with several at once, males must compete, said study co-author Niclas Kolm, an evolutionary biologist from the University of Uppsala in Sweden.
In this case, male fish that produce faster sperm have a better chance of beating rivals in the race to fertilise the few eggs that females lay.
Super-sperm
Furthermore, Kolm and his co-workers found some of the fish produce sperm that have evolved to become larger, more numerous and more long-lived. These are a kind of “super-sperm”, said the researchers, who detail their findings this week in the U.S. journal theProceedings of the National Academy of Sciences.
