Experimental Investigation of the Mate Choice Theory of Menopause with Drosophila Melanogaster

Abstract

Menopause, the complete cessation of menstrual cycles, apparently is a detrimental trait, yet all women experience it. Numerous theories have been proposed to explain the origin of menopause, but none has been satisfactory. In 2013, Morton et al. proposed a mate choice hypothesis to explain menopause and, using a computational model, showed how a bias in mating (i.e., older men preferring younger women) could have allowed such an otherwise detrimental trait to evolve neutrally through accumulation of female fertility-reducing mutations. To investigate whether biased mating could affect fecundity and fertility in a real system, two experimental populations were established using Drosophila melanogaster. Older males were mated with younger females and vice versa. Information was obtained, including data on fecundity, fertility, ovariole and matured egg chambers, and lifespan, for experimental, age-restricted-mating and control populations. A negative effect on the fecundity and fertility of the younger-mating sex was observed in restricted-mating compared to control populations. Age-restricted mating had no effect on longevity. Menopause could evolve according to the mate choice hypothesis.