title: Allopolyploid origins of the Galeopsis tetraploids--revisiting Müntzing's classical textbook example using molecular tools.
abstract: Whole-genome duplication coupled with hybridization is of prime importance in plant evolution. Here we reinvestigate Müntzing's classical example of allopolyploid speciation; the first report of experimental synthesis of a naturally occurring allopolyploid species, Galeopsis tetrahit. Various molecular markers (cpDNA, NRPA2, amplified fragment length polymorphisms (AFLPs)) and flow cytometry were surveyed in population samples of subgenus Galeopsis, including two allopolyploid species and their potential diploid parents. The presence of two divergent copies of single-copy NRPA2 confirms the allopolyploid origins of G. tetrahit and Galeopsis bifida. However, the two allopolyploids do not share the same maternal genome, as originally suggested by Müntzing. The results support independent origins, but not recurrent formation, of the two allotetraploids. Data further indicate frequent gene flow and introgression within ploidy levels, but less so between ploidy levels. Our results confirm and elaborate on Müntzing's classical conclusion about allopolyploid origins of G. tetrahit and G. bifida. We address questions of general interest within polyploidy research, such as recurrent formation, gene flow and introgression within and between ploidy levels.
authors: National Centre for Biosystematics, Natural History Museum, University of Oslo, PO Box 1172 Blindern, NO-0318 Oslo, Norway.
authors: Mika
authors: M
authors: Bendiksby
authors: Department of Organismic Biology, University of Salzburg, Hellbrunnerstrasse 34, A-5010 Salzburg, Austria.
authors: Andreas
authors: A
authors: Tribsch
authors: National Centre for Biosystematics, Natural History Museum, University of Oslo, PO Box 1172 Blindern, NO-0318 Oslo, Norway.
authors: Liv
authors: L
authors: Borgen
authors: Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43 Průhonice, Czech Republic.|Department of Botany, Faculty of Science, Charles University in Prague, CZ-128 01 Prague, Czech Republic.
authors: Pavel
authors: P
authors: Trávníček
authors: Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, PO Box 1066 Blindern, NO-0316 Oslo, Norway.
authors: Anne K
authors: AK
authors: Brysting
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