Statistical Analysis
A chi square analysis was used to evaluate if ratios in the F2 generation and backcrosses differed from expected. One way analysis of variance was used to test the effect of hatch and of type of mating on exhaustion scores. Heritability (h2) estimates were obtained from the linear regression coefficients of the exhaustion scores of F2 offspring on exhaustion scores of F1 parents for both reciprocal F1 crosses. The standard errors of the linear regression coefficients served as the approximate standard errors of the h2 estimates. Regressions were obtained for offspring on sires, offspring on dams, and offspring on mid-parent. Linear regression analyses were run for male and female offspring separately and for both sexes combined. Because hatch effects were significant, the linear regression coefficients were also obtained after the data were adjusted for hatch effects by subtracting the mean of each hatch from the individual values and adding a constant so that all values were positive.