A Conservative Procedure for the Estimation of Multiple Insemination in Drosophila

For certain Drosophila females, observation of the genotypes at an autosomal locus of a sample of their progeny confirms that they used the sperm from at least two males in fertilizing their offspring. In addition to these observably multiply mated females there are other females whose multiple matings are not apparent in the progeny sample. We relate the observed level of concurrent multiple paternity (CMP) to the true level of CMP by a multiplier which depends only on the gene frequencies and the progeny sample size. The simplicity of the relation between observed and estimated actual CMP is purchased at the cost of ignoring sperm displacement and triple mating. We argue that the resulting estimate still errs on the conservative side.