Marisa Almeida Rodrigues

I am interested in the evolution of life history traits. In my MSc project I examined the effects of macronutrient composition of the larval diet on life history traits and pigmentation in Drosophila virilis. For my PhD project (January 2016 – date) I am interested in exploring the physiological and metabolic mechanisms underlying the fecundity/longevity trade-off in the fruit fly (Drosophila melanogaster). My project, funded by a SNSF grant to Thomas Flatt, is part of a larger collaborative research unit, sponsored by the DFG (DFG FOR 2281, “Sociality and the reversal of the fecundity/longevity trade-off”) (http://gepris.dfg.de/gepris/projekt/261675780).

In many organisms curtailed reproduction increases lifespan. Conversely, extended lifespan is often accompanied by reduced reproduction. The overarching aim of our Research Unit (RU) is to investigate the evolution and mechanisms of the fecundity/ longevity trade-off in insects by comparing experimental manipulations in social insects, where – remarkably – the fecundity/longevity trade-off is typically absent, with data from solitary insects (e.g., Drosophila), where this trade-off is common and well-established. As a model for understanding the mechanisms underlying the fecundity/ longevity trade-off, we are planning to perform experiments in the fruit fly (Drosophila melanogaster), which shall serve as “solitary insect” reference system or “control” for the work to be done in social insects in our RU. The fact that decreased food intake without malnourishment (dietary restriction) extends lifespan while concomitantly reducing reproduction suggests that the longevity-reproduction trade-off might represent an energetic resource allocation trade-off. If so, food limitation might divert resources away from reproduction and make them available for somatic maintenance and survival. However, the trade-off in energy allocation between fecundity and metabolic storage is not quantitatively exact, and dietary restriction can increase lifespan in gonadectomized worms (Caenorhabditis elegans) and sterile flies (D. melanogaster), findings which are at odds with the resource allocation model. In contrast to C. elegans that lack the entire gonad, worms that lack germ cells only are long-lived, and dietary restriction cannot further extend longevity in these individuals, suggesting that signals from the germline may oppose those of the somatic gonad to regulate ageing in the worm. Therefore, although current knowledge indicates that nutrient metabolism, reproduction and ageing represent interconnected regulatory axes, the actual mechanisms underlying the trade-off between reproduction and longevity remain largely unknown. The main goal of the research proposed here to use the genetically powerful fruit fly model Drosophila melanogaster to test whether the reproductive and nutritional regulatory axes converge onto the same mechanisms that affect ageing. Specifically, we will use a sterile mutant with oogenic arrest and a germline-less, long-lived transgenic strain as experimentals tool to discover how reproduction interacts with diet to affect lifespan and physiology. To systematically characterize the global physiology underlying the fecundity/longevity trade-off in Drosophila we will combine transcriptomics, metabolomics, endocrine assays, and RNAi silencing of candidate genes.