Using laboratory selection for desiccation resistance to examine the relationship between respiratory pattern and...

We conducted concurrent measurements of rates of CO2 and H2O release from individual fruit flies Drosophila melanogaster taken from populations subjected to three different selective regimes: (1) populations selected for resistance to desiccation (D flies); (2) populations maintained as their controls (C flies); and (3) the ancestral populations of the D and C populations (O flies). In the D flies, water loss rates were significantly reduced, the standard error of the regression (SER) of the CO2 release pattern measured over the survival period of the flies was increased, and the ratio of CO2 loss to H2O loss (VCO2/VH2O) was increased. Correlations across all 15 populations from the three selection treatments indicate that survival time was negatively correlated with water loss rate, positively correlated with the SER of CO2 release and positively correlated with the VCO2/VH2O ratio. We did not, however, find a significant correlation between the SER of CO2 release and rates of water loss or the VCO2/VH2O ratio.