Price, T.A.R., Hodgson, D.J., Lewis, Z., Hurst, G.D.D., Wedell, N. (2008). Selfish genetic elements promote polyandry in a fly.  Science 322(5905): 1241--1243.

FBrf0206343

Research paper

It is unknown why females mate with multiple males when mating is frequently costly and a single copulation often provides enough sperm to fertilize all a female's eggs. One possibility is that remating increases the fitness of offspring, because fertilization success is biased toward the sperm of high-fitness males. We show that female Drosophila pseudoobscura evolved increased remating rates when exposed to the risk of mating with males carrying a deleterious sex ratio-distorting gene that also reduces sperm competitive ability. Because selfish genetic elements that reduce sperm competitive ability are generally associated with low genetic fitness, they may represent a common driver of the evolution of polyandry.