The effect of respiratory pattern on water loss in desiccation-resistant Drosophila melanogaster

We measured CO2 and H2O release from individual fruit flies from five popul ations of Drosophila melanogaster selected for resistance to desiccation (D flies). Our previous work found that these flies survive for an extended p eriod in dry air, have an increase in the peak height and frequency of CO2 release, as measured by the standard error of a linear regression (SER) of CO2 release for the entire survival period, and have reduced water loss rat es ((V) over dot (H2O)) compared with their control or ancestor populations . In the present study, we examined the following respiratory characteristi cs: (V) over dot (CO2), (V) over dot (H2O) the SER of CO2 release and the r atio of (V) over dot (CO2) to (V) over dot (H2O) in the D flies. Correlatio ns between these characters were calculated in order to determine the effec t of respiratory pattern on water loss. We found that, within the D flies, neither periodic release of CO2 nor an increased SER for CO2 release was as sociated with reduced water loss. In addition, an increased SER was positiv ely correlated with both an increased water loss rate and a decreased survi val time. Therefore, although selection for desiccation resistance leads to both an increased SER and a decreased rate of water loss in the D flies, t he increased SER does not significantly reduce respiratory water loss.