Multiple Insemination and Male Sexual Selection in Natural Populations of Drosophila pseudoobscura

Data are presented which indicate a high frequency of concurrent multiple paternity in the progeny of females in a natural population of Drosophila pseudoobscura. A probability model is presented and used to obtain maximum-likelihood estimates of parameters describing the pattern of sperm use and the amount of concurrent multiple paternity in several population samples. The probability that two randomly selected offspring from a single randomly selected female have the same father was found to be .79. Estimates of effective mating frequency of male genotypes suggest that one of the samples came from a population in which there was nonrandom mating. Some evolutionary consequences of multiple matings in Drosophila are discussed.