AVERAGE JOES BEAT CASANOVAS
Males that contribute nothing more to reproduction than sperm are usually best off putting all their efforts into mating with as many females as they can, as often as possible. There is such a thing as being too enthusiastic, though.
Male mosquitofish vary widely in terms of sex drive. “Selection ought to oust males that display low or average levels of sexual activity,” says Carolin Sommer-Trembo of Goethe University Frankfurt. “We wanted to know how this variation in male behavioural types is maintained.”
It comes down to female choice. Females actively avoid the most highly sexed males. That’s partly because such indefatigable suitors leave females with little time to feed. But also, their persistent attempts to copulate often inflict genital injuries. Little surprise then that females prefer to consort with males of a more reticent bent.
Ardent males do have their moments. They are particularly attractive to inexperienced females, for example, and to groups, when the male’s costly attentions can be shared among the school.
Male mosquitofish reach sexual maturity as young as 43 days.