Polyploidy

Review

Blackwell Publishing Ltd.

Research review
Advances in the study of polyploidy since Plant speciation

Author for correspondence: D. Soltis and P. Soltis Tel: +1 352 392 1721 Fax: +1 352 846 2154 Email: dsoltis@botany.ufl.edu and psoltis@flmnh.ufl.edu Received: 4 August 2003 Accepted: 29 September 2003 doi: 10.1046/j.1469-8137.2003.00948.x

Douglas E. Soltis1, Pamela S. Soltis2 andJennifer A. Tate2
1 2

Department of Botany and the Genetics Institute, University of Florida, Gainesville, FL 32611 USA; Florida Museum of Natural History and the Genetics Institute, University of Florida, Gainesville, FL

32611 USA

Summary
Key words: polyploidy, plant speciation, genetics, genomics, ecology. Enormous strides have been made in the study of polyploidy over the last 20 yr.Here, we highlight some of these discoveries and note where our understanding of polyploid evolution has changed. Genetic and genomic studies have dramatically altered the polyploidy paradigm. The estimated frequency of polyploidy has increased, and it is now recognized that multiple origins are the rule for most polyploids. Likewise, autopolyploidy is much more common than traditionallymaintained. Rapid genomic rearrangements, genomic downsizing, movement of genetic elements across genomes, and the movement of foreign genetic materials into the polyploid genome illustrate the complex dynamics of polyploid genomes. Following polyploidization, both genetic and epigenetic mechanisms may play an important role in altering gene expression. Ecological studies reveal that plant polyploidy canhave profound effects on interactions with animal herbivores and pollinators and that polyploidy may trigger changes in the reproductive biology of a species. Despite the recent advances in our understanding of polyploid evolution, many exciting aspects remain under-investigated. Some of these include the consequences of genetic and genomic changes in natural polyploid populations, thephysiological and ecological effects of polyploidy, and whether recurrent polyploidy prompts evolution to repeat itself. © New Phytologist (2003) 161: 173–191

Introduction
In Plant Speciation, Grant (1981) devoted five chapters (15% of the total text) to polyploidy, reflecting the importance of the topic both to the author and to plant biologists. We update Grant’s (1981) coverage by highlighting some ofthe more important discoveries in polyploid evolution during the

past 20 yr. Although enormous strides have been made in many areas of research, most new data fit neatly into topics covered by Grant over two decades ago. In particular, our understanding of the genetic and genomic consequences of polyploidy has increased dramatically. Genomic studies have dramatically altered the polyploidyparadigm. Flowering plants and perhaps all eukaryotes possess genomes with

© New Phytologist (2003) 161: 173 –191 www.newphytologist.org

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Research review

considerable gene redundancy, much of which is likely the result of whole genome duplication. Molecular studies in plants, as well as animals, have shown that recurrent polyploidy is the rule, not the exception; for muchof the plant world we should think in terms of origins of species. Genetic studies indicate that autopolyploidy is much more common than traditionally maintained and concomitantly reveal underlying genetic reasons for the success of these organisms. Genetic and genomic studies illustrate that polyploidy is a highly dynamic process with different polyploids responding to the evolutionary challengesof polyploid formation using different mechanisms. Rapid genomic rearrangements may occur in some polyploids, but not in others. There is evidence for genomic downsizing in some polyploids and the movement of genetic elements across genomes (intergenomic invasion), as well as the movement of foreign genetic materials into some polyploid genomes. Both genetic and epigenetic mechanisms may alter...