Transcriptional correlates of the trade-off between reproduction and somatic maintenance in Drosophila melanogaster

Life-history evolution entails the optimization of fitness components, but trade-offs often constrain this optimization. For example, reproductive effort typically trades off with other fitness-related traits such as lifespan, stress resistance, and immunity, thus leading to costs of reproduction. At the physiological level, such trade-offs can manifest themselves as resource (energy) allocation trade-offs, yet the underlying physiological mechanisms are incompletely understood. To further understand the physiological consequences of curtailed reproduction, we use germline-less (sterile) D. melanogaster as an experimental model. We compare transcriptomes of both young and old sterile versus fertile flies and as a function of dietary yeast levels. Reproductive effort versus investment into maintenance depends critically upon diet; by altering diet, we seek to manipulate resource acquisition and allocation. To examine changes in tissue-specific expression in response to reproductive and dietary manipulation, we analyzed expression in the brain and fat body, two tissues with major roles in metabolism and endocrine regulation.