Polyploidy: Genetics, Evolution and Ecology
Husband, Brian .
Evolutionary dynamics of polyploidy: implications for rapid speciation.
Polyploidy, or genome duplication, has occurred repeatedly throughout the diversification of plants and animals and are widely viewed as a rapid, mechanism of sympatric speciation. However, the specific pathways by which polyploids arise and establish within diploid populations, and the role of genome duplication versus selection in driving phenotypic divergence and reproductive isolation, are poorly understood. Here, I describe an ongoing research program into polyploid evolution and speciation in the perennial plant, fireweed (Chamerion angustifolium; Onagraceae). Using field experiments, experimental crosses, phylogeographic analyses and synthesized polyploids, a picture of a very dynamic system is emerging. Polyploid mutations arise at high frequencies but are generally opposed by strong frequency-dependent selection. Assortative mating, coupled with recurrent polyploid formation, favours the establishment of polyploids within diploid populations. However, experimental research on synthesized polyploids suggests that phenotypic divergence and pre-zygotic reproductive isolation are not fully established through genome duplication. Rather, divergence mediated by interactions between ploidies, may also be important. Our results suggest that the common portrayal of polyploid speciation is perhaps an oversimplification and underestimates the importance of the interaction between selection and genome duplication in guiding the evolution of species divergence.
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1 - University of Guelph, Integrative Biology, 488 Gordon St., Guelph, Ontario, N1G 2W1, Canada
Presentation Type: Symposium or Colloquium Presentation
Location: Room 2/Woodward
Date: Tuesday, July 29th, 2008
Time: 4:00 PM