ena-STUDY-University of Osnabrueck-04-05-2019-19:43:08:209-424
Phylogeography of Schivereckia podolica (Brassicaceae) and the evolutionary history of the European steppe
The genus Schivereckia (Brassicaceae) -now included in the genus Draba- comprises two species, S. podolica and S. doerfleri. Schivereckia podolica is an eastern European species of disjunct distribution in Russia, in the Ukraine, and Podolian-Galician outpost. Schivereckia doerfleri is reported from alpine fields of the Balkan Peninsula and from mountain chains in northern Anatolia, Turkey. Schivereckia podolica shares its ecological and biogeographic characteristics with a number of other steppe plants. These associations of “mysterious elements” give the impression of mountain and even alpine or arctic elements and attracted botanists since more than 100 years. The 'relic hypothesis' interprets the present locations of Schivereckia and its associates as relics of a formerly continuous distribution belt of a cool periglacial steppe vegetation. On the other side, it is hypothesised that Schivereckia podolica is indeed an ancient but not a relict species and is of Mediterranean origin. Thus, Schivereckia remains “one of the most mysterious species in florogenetic aspects”. We employed molecular markers such as nuclear ITS and chloroplast trnL-F sequencing, and DNA fingerprinting (RAPD) to elucidate the evolutionary history and historical biogeography of Schivereckia. RAPD data argue that this disjunction is the result of fragmentation of a formerly continuous distribution belt. Phylogenetic analyses revealed that the genus Schivereckia is monophyletic and nested within a highly supported clade of central Asian and Caucasian Draba species. No relations to Mediterranean Draba species could be detected. This supports the interpretation of Schivereckia as a glacial relic rather than a Mediterranean post-glacial immigrant. Our results argue for continuous persistence of certain steppe species since the Pleistocene, and support the view that the modern steppes of Europe are derived from Pleistocene glacial steppes.
The genus Schivereckia (Brassicaceae) -now included in the genus Draba- comprises two species, S. podolica and S. doerfleri. Schivereckia podolica is an eastern European species of disjunct distribution in Russia, in the Ukraine, and Podolian-Galician outpost. Schivereckia doerfleri is reported from alpine fields of the Balkan Peninsula and from mountain chains in northern Anatolia, Turkey. Schivereckia podolica shares its ecological and biogeographic characteristics with a number of other steppe plants. These associations of “mysterious elements” give the impression of mountain and even alpine or arctic elements and attracted botanists since more than 100 years. The 'relic hypothesis' interprets the present locations of Schivereckia and its associates as relics of a formerly continuous distribution belt of a cool periglacial steppe vegetation. On the other side, it is hypothesised that Schivereckia podolica is indeed an ancient but not a relict species and is of Mediterranean origin. Thus, Schivereckia remains “one of the most mysterious species in florogenetic aspects”. We employed molecular markers such as nuclear ITS and chloroplast trnL-F sequencing, and DNA fingerprinting (RAPD) to elucidate the evolutionary history and historical biogeography of Schivereckia. RAPD data argue that this disjunction is the result of fragmentation of a formerly continuous distribution belt. Phylogenetic analyses revealed that the genus Schivereckia is monophyletic and nested within a highly supported clade of central Asian and Caucasian Draba species. No relations to Mediterranean Draba species could be detected. This supports the interpretation of Schivereckia as a glacial relic rather than a Mediterranean post-glacial immigrant. Our results argue for continuous persistence of certain steppe species since the Pleistocene, and support the view that the modern steppes of Europe are derived from Pleistocene glacial steppes.