ALBERS, Melissa A; BRADLEY, Timothy J; University of California, Irvine; University of California, Irvine: Fecundity in Drosophila melanogaster populations selected for enhanced desiccation resistance

We investigated the effect of dehydration and subsequent rehydration on fecundity in five populations of Drosophila melanogaster selected for enhanced desiccation resistance (D populations) and their five paired control populations (C populations). Female flies were desiccated for 8h (C populations) or 24h (D populations) and then allowed to recover for 48h on distilled water, a saline solution, a saline+sucrose solution or on food. Each of these was tested with or without a yeast supplement. Flies were then placed individually in vials of food for 12h and the number of eggs laid during this time period was measured. Fecundity was also measured during the same 12h on flies that did not undergo a desiccation stress but were instead given food throughout the experiment. The flies that recovered in the presence of yeast had a greater fecundity within a specific recovery treatment than those flies recovering without yeast. The relative importance of osmotic recovery and dietary supplementation on fecundity will be discussed. The D populations showed a greatly reduced fecundity relative to the C populations when all populations were given yeast or when flies had not undergone desiccation. This reduced fecundity may be the result of a physiological trade-off due to high carbohydrate and low lipid levels in the D populations, a characteristic that has been positively correlated with desiccation resistance. A single bout of dehydration in flies of the C and D populations had no measurable effect on fecundity provided the flies are given a recovery period. Supported by NSF grant IBN 0079501