Metacommunity genetics in a plant-aphid system

Project: Research

Project Details

Description

In an ecological community, species interactions structure local populations and influence species coexistence. Two different, yet complementary, approaches to studying species interactions are community genetics, which recognises that within-species genetic variation can alter the interactions between different species; and, metacommunity ecology, which emphasizes the role dispersal plays in structuring local communities. We will investigate how community genetic interactions influence metacommunity dynamics, using a model tansy (Tanacetum vulgare) plant-aphid system. Individual tansy plants act as 'islands of resource' and, on this plant, classical metapopulation structuring is exhibited by competing specialist aphids and their parasitoids. Previous work shows that only a fraction of all plants in a population are occupied by aphids, even when located very close to one another. This indicates that aphids do not necessarily disperse to close-by plants, suggesting that aphid colonisation is not random. In this project, we will follow a community genetics approach to determine if genetic variation in tansy influences the population genetic structure of the aphids, and the interactions between aphids, their natural enemies and ants. Tansy also exhibits high intraspecific variation in volatile organic chemicals (VOCs), which can influence the preference of aphids and their natural enemies. Thus, we will analyse the profile of these chemicals and how this structures the aphid metacommunity. To quantify genetic variation among plants, we will use a RNA-sequencing approach to design primers to assess SNP variation across the plants. We will additionally use the RNA-seq data to conduct a targeted gene approach to further quantify differences in the expression of herbivore-induced terpene-synthase (tps) genes. We will set-up a common garden experiment using multiple plant genotypes within common chemotypes of tansy to compare the effect of chemotype variation versus other genetic variation. The community structure of aphids, ants, predators and parasitoids will be investigated in the field and in the common garden. Manipulation experiments will be used to uncover specific interactions among the species in the metacommunity. Here, we will use no-choice and choice tests to examine host preference and performance interactions within the metacommunity across chemotypes and genotypes within the chemotypes. These experiments will show if there is active choice (important for dispersal), and the potential for non-random association across genotypes and species. By collecting data on host preference and performance of the aphids and natural enemies we can estimate the effect these have on the resulting community structure, and posit hypotheses for herbivore coexistence in the system. Overall the project will shed light on fundamental mechanisms structuring ecological communities in the field.

StatusFinished
Effective start/end date1/01/1331/12/19

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