TABLE 2

Least-squares trait means (SEs) by background and treatment, and proportional decrease in trait mean within backgrounds, Δ = (control - treated)/control

Background
Trait (units)TreatmentUnloadedLoadedPa
A. Total productivityUnmutagenized210.5 (8.12)185.9 (8.12)
    (worms)Mutagenized125.8 (8.49)97.5 (8.38)
Δ0.40 (0.042)***0.48 (0.037)***0.10
B. Early productivityUnmutagenized133.1 (5.55)100.0 (5.55)
    (worms)Mutagenized57.0 (5.81)37.3 (5.74)
Δ0.57 (0.043)***0.64 (0.038)***0.21
C. Late productivityUnmutagenized77.5 (5.34)85.8 (5.34)
    (worms)Mutagenized68.8 (5.58)60.5 (5.52)
Δ0.11 (0.074)0.30 (0.056)***0.03
D. Relative fitness, wUnmutagenized1.00 (0.040)0.749 (0.040)
Mutagenized0.435 (0.042)0.285 (0.042)
Δ0.57 (0.041)***0.63 (0.038)***0.28
E. Longevity (days)Unmutagenized13.3 (0.285)13.2 (0.287)
Mutagenized12.7 (0.304)12.9 (0.298)
Δ0.047 (0.025)0.026 (0.022)0.57
  • a P values represent the difference in response on the two backgrounds and are calculated as P = 2a, where a is the proportion of bootstrap replicates out of 1000 in which the proportional decrease in mean was greater or less on the unloaded background than on the loaded background, whichever value is <0.5. This accounts for the two-tailed nature of the test.

  • ***Significant effect of mutagenesis within a background, P < 0.0006.