Annals of Botany Lecture - Dr. Pamela Soltis
Soltis, Pamela .
Angiosperm Phylogeny: The Role of Polyploidy in Diversification and Genome Evolution.
Angiosperm phylogeny is characterized by a series of rapid radiations that interrupt longer periods of stasis. Attempts to identify the intrinsic phenotypic characteristic(s) or ecological attributes responsible for these shifts in diversification rate have been unsuccessful. More recently, genomic data for Arabidopsis and other model organisms have revealed surprising levels of ancient polyploidy within the angiosperms. Furthermore, as genomic and transcriptomic data accumulate for additional species representing previously unsampled branches of the angiosperm tree, new instances of genome duplication are evident, many of which mark significant clades. In addition to ancient polyploidy within angiosperms, genome duplications can be traced to both the most recent common ancestor of all angiosperms and of all seed plants. Is it possible that repeated genome duplications served as catalysts for repeated radiations? Given the ubiquity of ancient polyploidy throughout the history of the angiosperms, it is surprising that most angiosperm genomes behave essentially as diploids, leading to questions of which processes are involved in the diploidization of polyploid genomes. Perhaps clues to the diploidization process may be gleaned from studies of recently formed polyploids, such as Tragopogon mirus and T. miscellus (Asteraceae), both of which formed in the early part of the 20th century. The genomes of these tetraploids, as well as those of wheat, cotton, Brassica napus, and others, reveal dynamic interactions between the parental contributions, with shifts in gene expression, changes in karyotype, and loss of chromosomal and genic material from one parental genome or the other. The microevolutionary processes observed in Tragopogon and other recent polyploids may provide the mechanisms to explain the essentially diploid genomes of most angiosperms. Furthermore, genome duplication may have triggered radiations by generating novel genomic combinations and thereby novel phenotypes. Given the widespread role of polyploidy as a speciation mechanism in recent angiosperm history, it is perhaps possible that polyploidy has played a long and fundamental role in shaping angiosperm genomes and in angiosperm evolution.
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1 - University of Florida, Florida Museum of Natural History, Gainesville, FL, 32611, USA
Presentation Type: Special Presentation
Location: Lenox Room/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 11:00 AM