The selection for acute withdrawal is illustrated in Fig. 2a. The ANOVA revealed a significant effect for line (F1,861=19, p<1.3 × 10−5), generation (F4,861=10, p<7 × 10−8), and the line × generation interaction (F4,861= 32, p<9 × 10−25). At S5, the difference in the CAUC between the High and Low lines was 12.7±1.4 vs 0.7± 0.9 (relative CAUC units). Over generations S3 to S5, the High Line was significantly different from the Low Line at p<1 × 10−4 or better (Tukey HSD for unequal N). Within the High Line, generations S3 to S5 differed from generations S1 and S2 at p<1 × 10−3 or better. Within the Low line, generation S3 differed significantly from generations S4 and S5 at p<0.02 and 0.01, respectively. Paralleling the segregation for the CAUC, there was also a segregation for the CMAX (Fig. 2b); the ANOVA revealed a significant line × generation interaction (F4,861=43, p<9 × 10−25). At S5, the difference between the High and Low lines was (in relative units) 3.4±0.2 vs 0.6±0.01 (p<1.2 × 10−5). During selection, there was a significant generation effect
