Fertility and viability at theSodlocus inDrosophila melanogaster: non-additive and asymmetric selection

Abstract

SummaryExperiments were designed to test inDrosophila melanogasterthe effect of mating type at theSodlocus on fertility and viability. The experiments show that fertility is neither additive (or multiplicative) nor symmetric, i.e. that the fertility of a mating type cannot be predicted from the average fertility of the two genotypes involved in the mating. There is no significant male x female interaction with respect or progeny viability; but the interaction is significant for productivity, i.e. when fertility and viability are jointly taken into account. There is overdominance with respect to female fertility, but not with respect to male fertility or to viability. There also is alloprocoptic selection with respect to fertility and with respect to productivity, i.e. matings between like homozygotes are less fertile and productive than matings between dissimilar homozygotes. Selection at theSodlocus yields stable polymorphic equilibria, with the frequency of theFallele predicted atP= 0·641 or 0·695, respectively for low and high larval density.