The inheritance of female mating behaviour in the seaweed fly,Coelopa frigida

Abstract

SummaryIn order to understand the evolution of female mate preferences it is important to determine whether the genes for the preference and those for the preferred character are linked. It has previously been shown that female preference in the seaweed fly,Coelopa frigida, varies with the αβ inversion system on chromosome I. This inversion system is known to genetically determine, at least in part, the male preferred character, large size. This study was undertaken to determine whether the genes determining mate preferences, as well as those determining female receptivity, co-inherit with the inversion. In the full sibs of animals recently collected from a natural population in Sweden it is shown that high acceptance rate and strong preference for large male size both co-segregate with the α form of the inversion, and that low acceptance rate and a weak preference for large size co-segregate with the β form of the inversion. Both sets of genes appear to be located in or near the αβ inversion. The heterogeneity between crosses suggests the natural population from which the animals were collected was polymorphic for behavioural genes on the β haplotype. Crosses involving animals that had been in laboratory culture for seven generations indicated that variation in female mating behaviour had been lost. Possible reasons for the apparent instability of such behaviour are discussed.