Drs. Siebe Van Wunnik
Terrestrial Ecology Unit
Department of Biology
Ghent University
K.L. Ledeganckstraat 35
9000 Gent Belgium
E-mail: Siebe.vanWunnik@UGent.be
The coevolution between white clover (Trifolium repens) and mites (Tetranychus urticae)
Species interact with each other in many different ways: predation, commensalism, parasitism, … . These interactions often have short-term effects on the population demography of the species (the ecology). They also exert strong evolutionary pressures on the species involved, affecting phenotypic and genetic diversity (evolution). This means that ecological and evolutionary processes are intertwined and can affect the same temporal and spatial scales. We want to test whether ecology or evolution is the main driver of population dynamics. We also hypothesize that their respective effects may differ in space, leading us to test the impact of dispersal on the geographic theory of mosaic evolution.
Our study focusses on the interaction between white clover (Trifolium repens) and two-spotted spider mites (Tetranychus urticae). Clover shows a polymorphism for cyanide production, which means that genotypes can be cyanogenic or acyanogenic. Cyanide-producing plants have a strong advantage when herbivores are abundant and are also more resistant to drought. However, in the absence of herbivores or during freezing, cyanide production is costly for the plant. In addition, mites possess an enzyme capable of detoxifying cyanide, the CAS (β-cyanoalanine) enzyme. This enzyme can be upregulated in the presence of cyanide, but there is still a large degree of intraspecific variation in this, meaning that there is variation in mite resistance to cyanide.
The study will be multifaceted, as we have a complementary molecular and systems approach. We will also carry out field surveys to validate our laboratory results. Finally, we will develop an individual-based model that simulates the plant-herbivore system. We will use our experimental results to determine the parameter values. This model will allow us to make predictions and quantify the drivers of plant-herbivore coexistence.
