Table 1. Statistical analyses of fly size variation at the start vs the end of positive size selection.
Effect | Population mean sizes | Upper quartile sizes | ||||
F | DF | p | F | DF | p | |
10 kPa vs 21 kPa: Generations 1 vs 11, during truncation selection for large size | ||||||
Females | Females | |||||
aPO2 | 69.09 | 2, 15 | <0.0001 | 89.75 | 2, 15 | <0.0001 |
Generation | 95.98 | 2, 15 | <0.0001 | 77.98 | 2, 15 | <0.0001 |
aPO2×Generation | 23.28 | 2, 15 | <0.0001 | 24.07 | 2, 15 | <0.0001 |
Males | Males | |||||
aPO2 | 45.32 | 2, 15 | <0.0001 | 95.52 | 2, 15 | <0.0001 |
Generation | 39.52 | 2, 15 | <0.0001 | 157.58 | 2, 15 | <0.0001 |
aPO2×Generation | 9.18 | 2, 15 | <0.0025 | 14.18 | 2, 15 | <0.0004 |
21 kPa vs 40 kPa: Generations 1 vs 11, during truncation selection for large size | ||||||
Females | Females | |||||
aPO2 | 0.05 | 2, 15 | 0.9531 | 4.36 | 2, 15 | <0.0322 |
Generation | 52.14 | 2, 15 | <0.0001 | 36.20 | 2, 15 | <0.0001 |
aPO2×Generation | 3.04 | 2, 15 | 0.0781 | 1.52 | 2, 15 | 0.2500 |
Males | Males | |||||
aPO2 | 0.921 | 2, 15 | 0.4197 | 0.71 | 2, 15 | 0.5084 |
Generation | 73.46 | 2, 15 | <0.0001 | 62.90 | 2, 15 | <0.0001 |
aPO2×Generation | 7.23 | 2, 15 | <0.0063 | 3.33 | 2, 15 | 0.0636 |
Repeated measures ANOVA statistics for the first and last generations that experienced directional selection for larger size, comparing hypoxic-reared (10 kPa, top) or hyperoxic-reared flies (40 kPa, bottom) to the control or normoxic-reared flies (21 kPa). Significant p values are boldfaced. In all cases, hypoxic-reared flies were significantly smaller than normoxic-reared flies, and responded differently than normoxic-reared flies. 10 kPa flies had a lesser increase in mass with size selection, indicated by significant aPO2×Generation terms. (F = F-ratio; DF = degrees of freedom).