Meiotic drive at the D(MD) locus and fertility in the mosquito, Aedes aegypti (L)

The Distorter gene D in Aedes aegypti shows meiotic drive when associated with the male-determining M gene, causing sex ratio distortion in favour of males. The fertility of Distorter (MD/m s) and normal (M/m-) males has been compared by mating them to a series of females at daily intervals and assessing egg production and yield of pupae. Individual males inseminated up to seven females (mean 4.4 to 4.5). Egg production by females mated to the two kinds of male was not significantly different. Mean eggs/clutch did not differ significantly between successive matings. The percentage of eggs yielding pupae was significantly lower for Distorter males, in all matings. This loss in fertility was more than enough to account for sex ratio distortion in terms of a differential reduction in functional X-bearing spermatozoa. It was equally obvious that zygotic or post-zygotic mortality could not have produced the observed sex ratio difference.