CO2 RELEASE PATTERNS IN DROSOPHILA-MELANOGASTER - THE EFFECT OF SELECTION FOR DESICCATION RESISTANCE

We used laboratory natural selection on insects as a means of investig ating the role of patterns of gas exchange in desiccation resistance. We used 15 populations of Drosophila melanogaster: five selected for d esiccation resistance, five control populations and five ancestral pop ulations. Using flow-through respirometry, we found that D, melanogast er from all populations produced irregular peaks of CO2 release, To qu antify the height and frequency of these peaks, we used the standard e rror of a linear regression (SER) through the recordings of CO2 releas e, The values for the SER were significantly larger in the populations selected for desiccation resistance than in the control and ancestral populations, Occasionally, highly periodic peaks of CO2 release were observed in the desiccation-resistant populations only, Maximum SER wa s found to be strongly correlated with survival time in dry air among selection treatments, but not among individuals within a population. A ccess to dietary water resulted in lower SER values. These data demons trate that gas exchange is physiologically controlled in Drosophila me lanogaster and that the pattern of gas exchange can change under selec tion, The relationship between these CO2 release patterns and classic discontinuous ventilation is discussed.