AN ANALYSIS OF RESOURCE-ALLOCATION IN RESPONSE TO DIETARY YEAST IN DROSOPHILA-MELANOGASTER

Drosophila melanogaster exhibit an increase in fecundity and a decreas e in length of life and starvation resistance when the diet is enriche d through the addition of live yeast. It has been proposed that this r epresents a necessary energetic trade-off between reproductive and som atic functions, We examined the metabolic aspects of this trade-off. W e measured egg production, dry wt, somatic lipid and carbohydrate stor age, and metabolic rate in response to changing amounts of live dietar y yeast. These variables were measured in five replicate populations s elected for postponed aging and five replicate short lived control pop ulations, We find that all ten populations show an overall increase in egg production and decrease in the amount of stored metabolites in th e presence of increasing amounts of yeast. All populations increase me tabolic rate in response to increasing amounts of live dietary yeast. The energetics of this phenomenon suggest that increased egg productio n results from increased acquisition of nutrients available in yeast w ith only a small redirection of resources from storage to egg producti on. (C) 1997 Elsevier Science Ltd.