Figure 4. Variation among treatments in water loss rates under normoxic conditions as measured at generation 29(24 hyperoxia).

Male (solid) and female (open) D. melanogaster evolved under normoxic, hypoxic, or hyperoxic conditions and were then raised in a common normoxic environment for two generations prior to conducting the assay. Treatment means ± SEM of replicate populations are shown for clarity. Body-mass corrected water loss rates were lower in females than in males (p = 0.0002), but there was no significant treatment effect (p = 0.099) nor sex×treatment interaction (p = 0.931).