title: Heteroploid reticulate evolution and taxonomic status of an endemic species with bicentric geographical distribution.
abstract: Reticulate evolution is considered to be among the main mechanisms of plant evolution, often leading to the establishment of new species. However, complex evolutionary scenarios result in a challenging definition of evolutionary and taxonomic units. In the present study, we aimed to examine the evolutionary origin and revise the species status of Campanula baumgartenii, a rare endemic species from the polyploid complex Campanula section Heterophylla. Morphometry, flow cytometric ploidy estimation, AFLPs, as well as chloroplast and nuclear DNA sequence markers were used to assess the morphological and genetic differentiation among C. baumgartenii, C. rotundifolia and other closely related taxa. Tetra- and hexaploid C. baumgartenii is morphologically and molecularly (AFLP) differentiated from sympatric C. rotundifolia. Contrasting signals from nuclear (ITS) and chloroplast (trnL-rpl32) markers suggest a hybrid origin of C. baumgartenii with C. rotundifolia and a taxon related to the alpine C. scheuchzeri as ancestors. Additionally, hexaploid C. baumgartenii currently hybridizes with co-occurring tetraploid C. rotundifolia resulting in pentaploid hybrids, for which C. baumgartenii serves as both seed and pollen donor. Based on the molecular and morphological differentiation, we propose to keep C. baumgartenii as a separate species. This study exemplifies that detailed population genetic studies can provide a solid basis for taxonomic delimitation within Campanula section Heterophylla as well as for sound identification of conservation targets.
authors.affiliation: Botany and Molecular Evolution, Senckenberg Research Institute and Natural History Museum Frankfurt, Senckenberganlage 25, D-60325 Frankfurt am Main, Germany.|Diversity, Evolution and Phylogeny of Higher Plants and Lichens, Institute for Ecology, Evolution and Diversity, Goethe University, Max-von-Laue-Str. 13, D-60438 Frankfurt am Main, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Uwe Nierbauer
authors.affiliation: Botany and Molecular Evolution, Senckenberg Research Institute and Natural History Museum Frankfurt, Senckenberganlage 25, D-60325 Frankfurt am Main, Germany jpaule@senckenberg.de.|Diversity, Evolution and Phylogeny of Higher Plants and Lichens, Institute for Ecology, Evolution and Diversity, Goethe University, Max-von-Laue-Str. 13, D-60438 Frankfurt am Main, Germany.
authors.forename: Juraj
authors.initials: J
authors.lastname: Paule
authors.affiliation: Botany and Molecular Evolution, Senckenberg Research Institute and Natural History Museum Frankfurt, Senckenberganlage 25, D-60325 Frankfurt am Main, Germany.|Diversity, Evolution and Phylogeny of Higher Plants and Lichens, Institute for Ecology, Evolution and Diversity, Goethe University, Max-von-Laue-Str. 13, D-60438 Frankfurt am Main, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Zizka
keywords: AFLP; Campanula sect. Heterophylla; ITS; cpDNA; flow cytometry; hybridization; polyploidy; rpl32-trnL.