Sonnleitner, Michaela , Weis, Birgit , Flatscher, Ruth , Escobar Garcia, Pedro , Schoenswetter, Peter , Schneeweiss, Gerald M. , Hülber, Karl .
Escaping minority cytotype exclusion - possible mechanisms of reproductive isolation among ploidy levels in Senecio carniolicus Willd. (Asteraceae).
Polyploidy, i.e. whole genome duplication, is recognized as a major factor contributing to diversification and speciation. Of particular interest are stable contact zones of diploid and polyploid cytotypes, where hypotheses on different pre-and postzygotic reproductive isolation mechanisms can be tested. An excellent study system is the European Alpine endemic Senecio carniolicus (Asteraceae), which comprises three main cytotypes (diploid, tetraploid, hexaploid), two of which (diploid and hexaploid) are frequently found within the same population. Nevertheless, the frequency of intermediate or odd cytotypes is very low (c. 1%) and suggests the presence of strong crossing barriers between the sympatric cytotypes. We investigated habitat and flowering time segregation, performed reciprocal crossing experiments among and within cytotypes and tested germination capacity of the resulting seeds as well as seedling vigour and performance. Spatial proximity and largely overlapping flowering times allow for extensive hybridization between cytotypes, and artificial inter-cytotype crossings produce clearly non-zero and sometimes substantial seed sets. Consequently, other processes, such as yet untested prezygotic or rather postzygotic isolating mechanisms are acting in this group.
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1 - University of Vienna, Department of Biogeography, Rennweg 14, Vienna, Vienna, A-1030, Austria
2 - University of Vienna, Department of Biogeography, Rennweg 14, Vienna, 1030, Austria
3 - Universitry of Vienna, Department of Biogeography, Rennweg 14, Vienna, Vienna, A-1030, Austria
4 - University of Innsbruck, Department of Systematics, Palynology and Geobotany, Institute of Botany, Sternwartestrasse 15, Innsbruck, A-6020, Austria
5 - University of Vienna, Department of Conservation Biology, Vegetation- and Landscape Ecology, Rennweg 14, Vienna, Vienna, A-1030, Austria
minority cytotype exclusion
Presentation Type: Poster:Posters for Sections
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM