ibclogo XVI International Botanical Congess


Abstract Number: 5262
Session = 20.5.2


BREEDING SYSTEMS, POPULATION GENETICS, AND PTERIDOPHYTE SPECIATION


Jakob Schneller, University of Zurich, Institute of Systematic Botany, Zollikerstrasse 107, CH-8008 Zurich, Switzerland


Most homosporous ferns have hermaphrodite gametophytes. Intragametophytic selfing leads (in one step) to completely homozygous sporophytes. Such a kind of breeding system determines the genetic structure of populations and the potential for selection and speciation. The existing hypothesis says that intragametophytic selfing is more frequently found in polyploid than in diploid species. Allopolyploidization leads to a genetic bottleneck which may be only partly reduced by multiple origin of polyploids. Existing mechanisms that promote outbreeding such as antheridiogens can be presented as arguments for the importance of genetic diversity within species populations. In long term, selective pressure on outbreeding is expected to be also important in polyploid species. The degree of genetic variability within polyploid species may give us information on multiple origin and on the time-scale of secondary speciation processes.


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