Ecological, genetic and climatic determinants of range expansion: a case study on Ceratocapnos claviculata in the native and invaded range
Final Report Abstract
By means of genetic analyses and field, common garden and growth-chamber experiments we studied the importance of dispersal, genetic diversity, founder effects, habitat quality and climate for the colonization and the establishment success of plant populations during range expansions. Using the data obtained in the project, a final aim was to model the past, present and potential range of the study species Ceratocapnos claviculata. This eu-atlantic, therophytic woodland species has been expanding during the past 40 years north- and eastwards into regions characterized by continental climate. The realized research program deviated slightly from the initial proposal for various reasons. For example, due to extremely low genetic diversity the planned landscape genetic analyses were not possible. Additionally, we used AFLP markers instead of microsatellites because the species is polymorphic. However, to compensate for parts of the proposal not realized, instead we collected and analyzed several hundred vegetation relevés with respect to the habitat requirements of the species. Furthermore, in order to obtain enough seeds for all experiments and in order to avoid maternal effects we cultivated more than 1000 individuals for seed production. Unfortunately, during harvest a large part of the plants was destroyed in a fire. However, we succeeded to recultivate plants which produced enough seeds for all experiments. Finally, we could carry out some additional experiments which were necessary to clarify some specific questions concerning the biology of the species. Genetic analysis showed that during postglacial natural range expansion from SW Europe northwards to Central and W Europe C. claviculata lost much of its genetic variability. In contrast, during the fast expansion of the past 40 years which was very probably human mediated, genetic diversity decreased only marginally. The different investigations of this study showed that despite very low genetic diversity in its northern native range and the newly invaded part of its range, C. claviculata established successful in the native and in the invaded range. This is surprising since the new range sites are more continental. However, field and pot experiments showed that the species is able to establish under a wide range of ecological conditions and that local microclimatic conditions may attenuate (macro)climatic extremes. Furthermore, expansion and establishment of C. claviculata seems to be positively influenced by anthropogenic disturbance such as found in forests with high silvicultural activity. There, the ruderal species finds optimum conditions for germination. Although very low temperatures exert negative effects on seed survival and germination, we expect that under ongoing climate change and anthropogenic disturbance in forests the opportunistic invader C. claviculata will keep on extending its range. A range model of the species using empirical data on the species biology obtained in the current project is still in progress.
Publications
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(2011): Vegetation databases as a tool to analyze factors affecting the range expansion of the forest understory herb Ceratocapnos claviculata. Journal of Vegetation Science
Voss, N.; Simmering, D.; Peppler-Lisbach, C.; Durka, W.; Eckstein, R.L.
