Ecological consequences of genetic variation: does genetic variation in a keystone parasitic plant species drive community response to infection?

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This work is concerned with the ecological consequences of genetic variation. Ecological communities are made up of populations of many interacting species. Different types of interactions between species (e.g. parasitism, competition, predator-prey interactions) will have different consequences for the individual players involved. The effects of interactions between two species can often also be seen on the whole community, in the presence, absence, abundance or behaviour of different species. Within a population of a single species, individuals will vary in their response to the environment and to other interacting species. If this variation has a genetic basis and is linked to the fitness of the individual it can be selected upon and the population can adapt and evolve. Genetic differences among individuals within a single species can change the outcome of the interactions between that species and other partners. These differences can often be seen at the community level as changes in species diversity or abundance. Changes in community species diversity caused by genetic variation within individuals can have large implications for the conservation and management of ecological communities and in how they respond to environmental change. The study focuses on the parasitic interactions of a single species with its hosts, how genetic variation within the parasite changes the outcome of interactions with host species, and the effect that this has on host community species diversity. The focal species is a parasitic plant called Yellow Rattle (Rhinanthus minor L.), which is common to grasslands in the UK, Europe and some parts of North America. Presence of Yellow Rattle within grassland can have profound effects on the wider community. Direct interactions with host plants indirectly change the competitive interactions between plants in the community, and can result in an increase in plant species diversity. Previous experimental work has shown that the outcome of interactions between Yellow Rattle and its hosts depends on genetic variation within host and parasite. The key aims of this work are to discover whether genetic diversity in the parasite population (high diversity verses low diversity), specific genetic identity of the parasite (the effects of individual genotypes), or geographic origin of the yellow rattle are important factors in determining the outcome of infection on the host community, and the resultant change in host community species biodiversity. Secondary aims are to examine the role that host species diversity plays in conjunction with parasite genetic diversity in shaping grassland community structure. The work will provide valuable information for conservation management policy on how important genetic diversity is in maintaining species biodiversity in ecological communities. The research will begin in 2011 and continue for 3 years. It will be undertaken at the University of Sussex, Falmer, Brighton and will build on current work by researchers at the University on the ecology of Yellow Rattle. Genetic analysis of Yellow Rattle will be undertaken at, and in collaboration with, researchers from the NERC Biomolecular facility in Sheffield.