The effect of multiple paternity on the genetically effective size of a population

With the availability of highly variable microsatellite loci, many previously elusive aspects of the lives of animals have been revealed. One important finding is that multiple paternity (MP) appears to be somewhat common throughout the metazoa. Frequently, along with the discovery of MP are assertions that it can increase the genetically effective size of the population (N(E)). I argue that MP is not likely to have a positive effect on N(E) because it increases the variance in male reproductive success. Published studies suggesting the contrary have implicitly or explicitly included other changes to the breeding system, and these additions are likely responsible for the presumed increase in N(E).