Precise sex ratios in highly inbred parasitic wasps ( Goniozus- emigratus/gordhi).

Highly inbred parasitic wasps should produce precise and highly female-biased sex ratios. The selective advantage of a precise sex ratio is 5%-30% for the cases considered here. Laboratory studies show that parasitic wasps do, in fact, produce precise sex ratios. Goniozus gordhi produces exactly one male as a rule in small clutches of eggs, and tends to produce more only in larger clutches. Goniozus emigratus, which has larger clutches, generally produces more than one male per clutch, but the variance in the number of males is half what it would be if sex determination were binomial. An evolutionary advantage of arrhenotoky is that it makes possible precise sex ratios, which provide a selective advantage in highly inbred species. -from Authors