Effects of age on water balance in Drosophila species

Age-related declines in physiological performance have been documented in a wide variety of organisms. However, it is unknown whether related species age in a similar manner or whether physiological differences associated wit h aging differ widely among species. Previous work has shown that the desic cation resistance of Drosophila melanogaster decreases rapidly with age. Ot her Drosophila species may have delayed reproductive maturity or may inhabi t arid habitats, so that age-related changes in water balance may be a sign ificant physiological constraint on their ecological success. We may, there fore, predict that physiological systems involved in water balance will det eriorate with age at a reduced rate in these species. We quantified several components of water budgets for 14 species of Drosophila, including both d esert and mesic representatives differing in their age of maturity. Desicca tion resistance decreased with age in all but one species studied, primaril y because of increased rates of water loss. However, there was no significa nt relationship between the rate of aging, as indicated by the rate of incr ease in water-loss rates as flies aged, and either habitat or age of maturi ty.