When environments vary over time and space individuals can be ‘mismatched' - in an environment to which they are not adapted. In the short term, individuals may show plastic responses, which can buffer deleterious effects. Given sufficient evolutionary time and selection, organisms will also adapt genetically. This project aims to explore these ideas in a novel conceptual framework developed from hominin evolution.

Modern human life histories were selected in a very different environment to that now experienced in industrialised countries. This very recent ‘mismatch' may explain the rapid and continuing rise in obesity and type 2 diabetes. The ‘thrifty genotype' hypothesis proposes that individuals selected in an environment of periodic food shortage will be efficient storing fat when food is plentiful. However, in environments in which food is in continual excess, such a genotype is maladaptive. A second variation on this idea is plasticity to the prevailing environment (‘thrifty phenotype'). Here, during development, the likely quality of the environment into which the individual will emerge is ‘assessed'. Thus traits such as insulin sensitivity are plastic and can be ‘set' during development. However, if the environment changes rapidly, the organism is set for the wrong environment, with deleterious consequences.

These ideas have untapped potential and broad relevance for the ecological domain. The aim is to exploit this by investigating untested predictions of the thrifty phenotype and genotype hypotheses, using ecologically relevant manipulations of diet in the fruitfly model system. The main aims are:

1. To measure genetic variation in ‘thrifty genotype'

This hypothesis proposes that increased efficiency of fat storage is advantageous when food supply is variable / scarce. The PI's lab created 3-fold replicated experimental evolution lines over 10 years years ago in which food supply is either ‘regular' or ‘random'. The random lines experience periods of starvation and glut and should therefore be selected for high efficiency fat storage. Total lipid storage and circulating sugars levels will be quantified. The full life history (lifespan, reproductive output) of the random and regular regimes will also be characterised.

2. To measure genetic variation in the expression of ‘thrifty phenotype'

In additional experimental evolution lines we have replicated regimes that experience good quality food during development, but emerge onto either a high or low quality adult diet. Hence low adult diet individuals are ‘mismatched' over evolutionary time. We will conduct the tests above to determine the significance of these mismatches.

3. To measure the extent of plasticity in ‘matching' of genotype to phenotype

The student will create proximate mismatches between developmental and adult environments by placing cohorts of wild type individuals on different larval and adult diets. This will show the extent of plasticity to mismatched environments. The full range of tests will be conducted as above.

Training: The student will enter UEA's personal and professional development programme. Through this they will gain personally tailored training in generic skills, career development and employability. Specific skills include analysing responses to experimental evolution, life history assays, biochemical tests of nutrient levels and quantitative analyses.

Fricke, C., Bretman A. & Chapman, T. (2009) Female nutritional status determines the magnitude and sign of responses to a male ejaculate signal in Drosophila melanogaster. J. Evol Biol. 23, 157-165.

Barnes, A.I., Wigby, S., Boone, J., Partridge, L. & Chapman, T. (2008) Feeding, fecundity and lifespan in female Drosophila melanogaster. Proc. R. Soc. B. 275, 1675-1683.

Fricke, C., Bretman, A. & Chapman, T. (2008) Adult male nutrition and reproductive success in Drosophila melanogaster Evolution 62, 3170-3177.
Review papers:

Flatt, T., and Schmidt, P.S. 2009. Integrating evolutionary and molecular genetics of aging. Biochimica et Biophysica Acta. 1970:951-962.

Partridge, L., M. D. W. Piper, et al. (2005). Dietary restriction in Drosophila. Mech AgeDev 126: 938-950