DYNAMICS OF POLYPLOID FORMATION IN TRAGOPOGON (ASTERACEAE): RECURRENT FORMATION, GENE FLOW, AND POPULATION STRUCTURE

• Published in: Evolution Vol. 64; no. 7; pp. 1984 - 2003
• Main Authors: Symonds, V. Vaughan, Soltis, Pamela S., Soltis, Douglas E.
• Format: Journal Article
• Language: English
• Published: Malden, USA Blackwell Publishing Inc 01-07-2010; Wiley Periodicals Inc; Oxford University Press
• Subjects: Alleles; Biological Evolution; Diploidy; Evolution; Evolution & development; Evolutionary genetics; Flowers & plants; Gene Flow; Genes; Genetic loci; Genetic Variation; Genetics, Population; Genotypes; hybridization; Hybridization, Genetic; Idaho; Linkage Disequilibrium; Microsatellite Repeats - genetics; Plant populations; Polyploidy; Population genetics; Population structure; reproductive isolation; speciation; Species Specificity; Tragopogon - genetics; Washington; Idaho; Washington; North America
• ISSN: 0014-3820; 1558-5646
• DOI: 10.1111/j.1558-5646.2010.00978.x

Polyploidy is a major feature of angiosperm evolution and diversification. Most polyploid species have formed multiple times, yet we know little about the genetic consequences of recurrent formations. Among the clearest examples of recurrent polyploidy are Tragopogón mirus and T. miscellus (Asteraceae), each of which has formed repeatedly in the last ~ 80 years from known diploid progenitors in western North America. Here, we apply progenitor-specific microsatellite markers to examine the genetic contributions to each tetraploid species and to assess gene flow among populations of independent formation. These data provide fine-scale resolution of independent origins for both polyploid species. Importantly, multiple origins have resulted in considerable genetic variation within both polyploid species; however, the patterns of variation detected in the polyploids contrast with those observed in extant populations of the diploid progenitors. The genotypes detected in the two polyploid species appear to represent a snapshot of historical population structure in the diploid progenitors, rather than modern diploid genotypes. Our data also indicate a lack of gene flow among polyploid plants of independent origin, even when they co-occur, suggesting potential reproductive barriers among separate lineages in both polyploid species.