Mating issues drove evolution of better disease carriers
The relentless spread of malaria may be largely a side effect of a long, slow battle of the sexes among mosquitoes.
Certain reproductive quirks of male and female Anopheles mosquitoes look as if they evolved in some back-and-forth scenario, researchers report in the Feb. 27 Science. In four of 16 species analyzed, males dose their sperm packages with unusually large amounts of a steroid hormone. Among other effects, it virtually ensures a male that he alone will father all the offspring of the hormone’s recipient. In turn, females of these species make their own compound that modifies the steroid’s activity in their bodies. Out of all this sexual chemistry come traits that help make these four species among the most dangerous malaria spreaders for people.