Exceptions can become the rule: genetic differentiation and migration history of a rare annual plant species on Svalbard.

Presence of annual plant species in the Arctic plant communities of Svalbard is an exception, and, presence of a thermophilous annual plant species is a rare exception. Predicted climate warming could make these exceptions to become the rule. Understandin g historical migration events, in particularly those related to global climatic changes such as past glaciations could provide a key to predicting future transformations of the Arctic flora. Recently, molecular markers have been successfully used to trace historical routes of immigration of perennial plant species to Svalbard. Annual plants have never been studied in this regard. A rare annual thermophilous plant Euphrasia (Orobanchaceae) is selected as a model object. Present state of Euphrasia populatio ns in Svalbard will be characterized as a result of field studies. Data on plant distribution, morphological variation, substrate conditions and plant community will be obtained. Genetic variation of Euphrasia populations in Svalbard, as well as of a set of potential source populations will be investigated using two molecular markers (AFLP and cpDNA sequences). Phylogeograpic methodology, such as Bayesian clustering, multilocus assignment tests, tree- and network building, will be applied to test whether existing populations of Euphrasia in Svalbard are the result of independent dispersal events, whether it was post-glacial colonization or glacial survival, and propose their potential source region(s). Taxonomic complexity of Euphrasia, a major challenge for previous research, will be overcome through international collaboration with Russian expert in taxonomy of Euphrasia. Norwegian and Russian experts will work together at all stages of the research programme, making international aspect an important p rerequisite and exciting feature of this project. National Center for Biosystematics will host laboratory research, while all field studies will be carried out on Svalbard mainly at Ny-Ålesund research station.