title: Using experimental evolution to study the physiological mechanisms of desiccation resistance in Drosophila melanogaster.
abstract: Data from populations undergoing experimental evolution can be used to make comparisons between physiologically differentiated populations and to determine evolutionary trajectories. Comparisons of long-established laboratory populations of Drosophila melanogaster that are strongly differentiated with respect to desiccation resistance are used to test alternative hypotheses concerning the mechanisms that fruit flies use to survive bouts of extreme desiccation. This comparative study supports the hypothesis that, in at least one case, D. melanogaster can evolve increased resistance to desiccation by decreasing water loss rates and by increasing bulk water content but not by increasing metabolic water content or dehydration tolerance. While glycogen was involved in water storage, its primary role was in water binding, not the production of metabolic water. Measurement of the trajectories of these component mechanisms during selection for desiccation resistance is used to demonstrate that water loss rate quickly plateaus in response to selection, while water content continues to improve. This disparity reveals the value of studying evolutionary trajectories and the need for longer-term selection studies in evolutionary physiology.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California, Irvine, California 92617, USA.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Archer
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Bradley
authors.forename: Laurence D
authors.initials: LD
authors.lastname: Mueller
authors.forename: Michael R
authors.initials: MR
authors.lastname: Rose
mesh_terms: D000818:Animals; D003890:Desiccation; D004331:Drosophila melanogaster / Q000502:physiology*; D005260:Female; D006003:Glycogen / Q000032:analysis; D008055:Lipids / Q000032:analysis; D008297:Male; D008954:Models, Biological; D012044:Regression Analysis; D012641:Selection, Genetic; D014867:Water / Q000032:analysis
chemical_list: D008055:Lipids; D014867:Water; D006003:Glycogen