This interesting paper investigates whether there is a relationship between polyandry and selfish genetic elements, in the fruit fly Drosophila pseudoobscura.
Polyandry - where females have multiple mating partners - is widespread in animals, but despite its frequency, little is known of the costs and benefits of this reproductive strategy (though this paper cites evidence that the costs of multiple mating appear to outweigh the benefits. It is likely that the benefits lie in that polyandry gives the female a greater degree of control over paternity, via sperm competition. There is also a possibility that selfish genetic elements may promote polyandry by correlating male fitness with sperm competition.