Genetic and environmental variation in the effect of dietary restriction on life-history trade-offs and ageing in Drosophila

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Understanding the causes and consequences of variation in longevity and ageing is important not only in the context of life history evolution, but also in our attempts to understand and mitigate these processes in humans. Life history theory predicts that variation in longevity and ageing is related to the trade-off between survival and reproduction. Dietary restriction (DR), a modest reduction in nutrient intake, has been shown to increase longevity and slow rates of ageing across a diverse range of species. The evolutionary explanation for this prolongevity effect of DR is that it alters the trade-off between survival and reproduction in the favour of increased investment in survival. Although the effect of DR is thought to be evolutionarily conserved, recent studies suggest genetic variation in the response to DR. In addition, recent theory has questioned whether the prolongevity and anti-ageing effect of DR will persist when organisms are exposed to ecologically relevant stressors such as pathogens, physical injury and temperature variation. Understanding the extent of this variation in the response of longevity and ageing to diet is clearly important in improving our understanding of the ageing process, how it might be mediated by diet and how this may vary between individuals and environments. This project will use Drosophila melanogaster as a model organism in which to provide detailed studies of genetic variation in the response to DR and the effect of exposure to environmental stress.Drosophila will be reared on diets that differ in yeast content and the effect of these diets on longevity, reproduction and ageing in various traits will be assessed. Using the Drosophila Genetic Reference Panel (DGRP) (~ 200 inbred lines of Drosophila), quantitative genetic experiments will be performed to allow estimation of the quantitative genetic variation in the response to DR and how DR influences the genetic (co)variation between life history traits; a key measure of life history trade-offs. The existence of genome wide sequence data for these lines will allow investigation of candidate genes underlying this variation. In addition, Drosophila on different diets will be exposed to environmental stressors including pathogens, physical injury and temperature variation to assess the effect of environmental variation on the response to DR. This PhD will provide training in the design, implementation and analysis of complex experiments across multiple generations as well as learning techniques for assaying and analysing traits such as growth, survival, physical performance etc. In addition, Drosophila melanogaster represent an incredibly well studied and flexible system that will allow a student scope to develop their own ideas.