This project is one of a number that are in competition for funding from the NERC Great Western Four+ Doctoral Training Partnership (GW4+ DTP). The GW4+ DTP consists of the Great Western Four alliance of the University of Bath, University of Bristol, Cardiff University and the University of Exeter plus five Research Organisation partners: British Antarctic Survey, British Geological Survey, Centre for Ecology and Hydrology, the Natural History Museum and Plymouth Marine Laboratory. The partnership aims to provide a broad training in earth and environmental sciences, designed to train tomorrow’s leaders in earth and environmental science. For further details about the programme please see http://nercgw4plus.ac.uk/
Location: University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE.
Prof Alastair Wilson Department of Biosciences, College of Life and Environmental Sciences, University of Exeter.
Dr Jon Bridle School of Biological Sciences, Universitry of Bristol.
Dr Andrew Young Department of Biosciences, College of Life and Environmental Sciences, University of Exeter.
Dr Natalie Cooper, Natural History Museum (Collaborative Partner)
This project will test a long-standing evolutionary hypothesis – namely that sets of phenotypic traits will diverge among populations along genetic ‘lines of least resistance’. This idea provides an important link between our understanding of ‘micro-evolution’ which occurs when natural selection drives genetic change within populations, and ‘macro-evolutionary’ patterns of differentiation that drive the evolution of new species. Within populations, some traits, or trait combinations, are more genetically variable than others. This creates ‘lines of least resistance’, which are directions of phenotypic change along which evolution by natural selection should be able to occur more rapidly. However, is macro-evolutionary population divergence really greatest along the directions predicted by assays of trait correlations, and how constant or predictable are these across different environments? And if so, is natural selection always the driver, or are differences among populations better explained by neutral processes (genetic drift, gene flow among populations). These long standing questions have rarely been addressed empirically, despite their importance in predicting evolutionary trajectories under conditions of continued environmental change. This project seeks to do just that, using captive populations of the Trinidadian guppy (Poecilia reticulata) as a model system.
Project Aims and Methods
The broad goal of the project is to determine whether adaptive evolution along lines of least resistance accounts for (multivariate) phenotypic differentiation among populations of guppies. The specific aims of the project, and the methods used to address them will be developed by the student depending on their particular interests, and with support from the supervisory team. However, project aims are likely to include:
1) Determining the structure of phenotypic variation within and among populations for suites of traits (including behavioural, life history, and morphological traits, and potentially some physiological traits)
2) Testing whether patterns of (genetic) trait divergence among populations in a common lab environment can be predicted by within-population genetic variance (determined from breeding experiments)
3) Using genomic and ecological data to determine the relative importance of natural selection, gene flow (within rivers) and genetic drift in shaping among-population differentiation.
This project will explore evolution across populations of the Trinidadian guppy that have evolved under very different predation - and so selection- regimes. It will be primarily lab-based, focusing on 12 colonies of fish currently housed in the Penryn aquatic facility that are derived from wild parents collected in 2017.
References / Background reading list
1. Schluter 1996. Adaptive radiation along genetic lines of least resistance. Evolution, 50, 1766–1774.
2. O'Brien, Higgie, Reynolds, Hoffmann & Bridle 2017, ‘Testing for local adaptation and evolutionary potential along altitudinal gradients in rainforest Drosophila: beyond laboratory estimates’. Global Change Biology, 23, 1847-1860.
3. Reznick & Endler The impact of predation on life history evolution in Trinidadian guppies (Poecilia reticulata). Evolution, 36, 160-177.
4. White & Wilson 2018. Evolutionary genetics of personality in the Trinidadian guppy I: Maternal and additive genetic effects across ontogeny. Heredity, doi: 10.1038/s41437-018-0082-1. [Epub ahead of print]
5. Wilson, Réale, Clements, Morrissey, Postma, Walling, Kruuk, Nussey 2010. An ecologist’s guide to the animal model. Journal of Animal Ecology, 79, 13-26