TABLE 4.

Estimates of the degree of dominance for second chromosome viability

Generation no.	E() ± SE
41	−0.05 ± 0.16 (NS)
77–85a	0.23 ± 0.08**
77–85b	0.39 ± 0.18*

is the average degree of dominance of viability mutations weighed by their squared homozygous effect, estimated as the regression of the average heterozygous viability of MA2 chromosomes on the genetic value of the corresponding average homozygous viability. NS, Not significantly different from zero. *Significantly different from zero (P < 0.013). **This standard error, which does not include the between-generation variability for the degree of dominance, implies that the estimate is significantly different from zero (P < 0.0017).

^aAverage of estimates computed separately for generations 77 and 85.

^bEstimate computed using over-generation values for homozygous and heterozygous viabilities.