Mating ability of P. pacificus strains. Strains are ordered according to the rates of X chromosome non-disjunction at 20°C (black bars), from highest to lowest. Shaded bars represent the proportion of males in the progeny of successful crosses. Numbers above bars indicate the percentage of crosses that resulted in cross-progeny out of 10 replicates (except for RS106 and RS5200, which had 9 replicates). Error bars indicate standard errors.