THE PROMISCUOUS AND THE CHASTE: FREQUENT ALLOPOLYPLOID SPECIATION AND ITS GENOMIC CONSEQUENCES IN AMERICAN DAISIES (MELAMPODIUM SECT. MELAMPODIUM; ASTERACEAE)
Article first published online: 6 SEP 2011
© 2011 The Author(s). Evolution © 2011 The Society for the Study of Evolution.
Volume 66, Issue 1, pages 211–228, January 2012
How to Cite
Weiss-Schneeweiss, H., Blöch, C., Turner, B., Villaseñor, J. L., Stuessy, T. F. and Schneeweiss, G. M. (2012), THE PROMISCUOUS AND THE CHASTE: FREQUENT ALLOPOLYPLOID SPECIATION AND ITS GENOMIC CONSEQUENCES IN AMERICAN DAISIES (MELAMPODIUM SECT. MELAMPODIUM; ASTERACEAE). Evolution, 66: 211–228. doi: 10.1111/j.1558-5646.2011.01424.x
- Issue published online: 3 JAN 2012
- Article first published online: 6 SEP 2011
- Accepted manuscript online: 29 JUL 2011 02:10PM EST
- Received February 21, 2011, Accepted July 8, 2011, Data Archived: Dryad doi:10.5061/dryad.3n148
- chromosome evolution;
- fluorescence in situ hybridization;
- genome size;
Polyploidy, an important factor in eukaryotic evolution, is especially abundant in angiosperms, where it often acts in concert with hybridization to produce allopolyploids. The application of molecular phylogenetic techniques has identified the origins of numerous allopolyploids, but little is known on genomic and chromosomal consequences of allopolyploidization, despite their important role in conferring divergence of allopolyploids from their parental species. Here, using several plastid and nuclear sequence markers, we clarify the origin of tetra- and hexaploids in a group of American daisies, allowing characterization of genome dynamics in polyploids compared to their diploid ancestors. All polyploid species are allopolyploids. Among the four diploid gene pools, the propensity for allopolyploidization is unevenly distributed phylogenetically with a few species apparently more prone to participate, but the underlying causes remain unclear. Polyploid genomes are characterized by differential loss of ribosomal DNA loci (5S and 35S rDNA), known hotspots of chromosomal evolution, but show genome size additivity, suggesting limited changes beyond those affecting rDNA loci or the presence of processes counterbalancing genome reduction. Patterns of rDNA sequence conversion and provenance of the lost loci are highly idiosyncratic and differ even between allopolyploids of identical parentage, indicating that allopolyploids deriving from the same lower-ploid parental species can follow different evolutionary trajectories.