Using laboratory selection for desiccation resistance to examine the relationship between respiratory pattern and water loss in insects

We conducted concurrent measurements of rates of CO2 and H2O release from i ndividual fruit flies Drosophila melanogaster taken from populations subjec ted to three different selective regimes: (1) populations selected for resi stance to desiccation (D flies); (2) populations maintained as their contro ls (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 ((V) over dot (CO2)/(V) over dot (H2O))) was increased. Co rrelations across all 15 populations from the three selection treatments in dicate that survival time was negatively correlated with water loss rate, p ositively correlated with the SER of CO2 release and positively correlated with the (V) over dot (CO2)/(V) over dot (H2O) ratio. We did not, however f ind a significant correlation between the SER of CO2 release and rates of w ater loss or the (V) over dot (CO2)/(V) over dot (H2O) ratio.