As an ecologist I’m interested in the key factors in the evolution of plant traits and the origin and maintenance of biological variation. To identify these key factors it is necessary to relate plant traits to fitness and selection in different environments and to study how the genetic composition of an individual through its interaction with the environment is translated into the phenotype. By doing so, ecology bridges the gap between genomics, physiology and metabolomics on the one hand and the study of evolutionary change and biodiversity on the other. This is not merely of pure scientific interest. Identifying key ecological processes and fitness related traits helps to predict how plants and animals will be affected both directly and on an evolutionary time scale by changing environments. Identifying fitness-related genes and metabolites (e.g. related to herbivore resistance) are also important in the field of agrobiology. We run several programmes with plant breeders aimed at increasing resistance in ornamental and food plants. After starting out on population dynamics of biennial plants, my research interest shifted towards evolutionary questions related to plant defence and plant reproductive systems. With various colleagues I worked on evolution of semelparity, age of first reproduction, attractiveness, selective abortion, sex allocation and diversity of secondary metabolites. All these projects have a similar approach. The starting point is a theoretical framework. Modelling and studying the most relevant ecological processes allows us to use experimental data to test quantitative and qualitative predictions on evolution and optimization. For the research on biodiscovery and natural products the Plant Ecology group worked closely together with the metabolomics group of the IBl. This resulted in several papers on plant defence based on metabolomic analysis. Presently the plant ecology group is merging with part of the metabolomics group of the IBL and will continue as the Plant Ecology and Phytochemistry Group.

To me, the challenge of (plant-) ecology today is to combine ecological studies with molecular and metabolomic approaches in order to obtain new and deeper insights in the way individuals can adapt to their environments. While continuing working on the evolution of reproductive systems, the emphasis of my work shifted since 2005 towards the evolutionary ecology of plant animal interactions. In this work I team up with Dr. K. Vrieling (molecular ecology). We want to i) identify factors related to defence ii) determine their costs and benefits iii) determine the underlying genetics and iv) determine their distribution within and among related plant species to study their evolutionary history. Ideally, for this type of study, one wants to use plants that differ as much as possible with regard to the trait under consideration but that are otherwise genetically similar. Often the genetic variation within species is limited and traits may be correlated. We developed a new approach. As a model system we use hybrids of Senecio species that occur in contrasting habitats (S. jacobaea and S. aquaticus, species of dry and wet habitats, respectively).We crossed these hybrids and produced an F2 generation to generate maximum (genetic) variation of relevant traits against an, on average, equal genetic background. The parental species, the F1-genotypes and 100 F2 genotypes are all kept in tissue culture so that we can reproduce the same genotypes ad lib. Currently we are mapping the cross and this will be finished in December 2008.The research approach is to test the fitness of these hybrids in different environments and to determine the most relevant ecological processes. If the success (fitness) of the offspring of these crosses is determined it is possible to identify fitness related molecular markers, e.g. for thrips resistance. Similarly it is possible to identify fitness-related metabolites (by e.g. NMR-analysis). The importance of the identified metabolites will further be studied in bioassays. Combining the molecular and chemical analysis will show if the fitness-related molecular markers are likely to represent genes coding for the identified compounds. In a later stage the actual genes can be identified and sequenced in cooperation with the molecular groups of the IBL. The distribution of compounds (and genes) amongSenecio species together with their phylogeny will make it possible to study the evolutionary history of the trait. This will be done in cooperation with the NHN-Leiden. The study of a suit of fitness related traits with the same genotypes representing all possible combinations of characteristics from two different habitats will make it possible to study fundamental ecological concepts such as: “a jack of all trades is a master of none” and basic “tradeoffs” and limitations to selection. We have chosen to start this project by focussing on an ecologically and economically important trait: resistance against herbivores and soil-born pathogens (together with Hans van Veen). Whenever possible the results on resistance will be incorporated in our applied research on resistance in chrysanthemums and tomatoes. Other relevant traits (such as life-history and reproductive traits, drought and flooding resistance) and species combinations will, in a later stage, be included. We will set up a database containing all relevant ecological, chemical and molecular information about the genotypes and make our stock of tissue-culture genotypes available for other (international) research groups.