Most Compositae (Asteraceae) are descendants of a paleohexaploid and all share a paleotetraploid ancestor with the Calyceraceae.
Like many other flowering plants, members of the Compositae (Asteraceae) have a polyploid ancestry. Previous analyses found evidence for an ancient duplication or possibly triplication in the early evolutionary history of the family. We sought to better place this paleopolyploidy in the phylogeny and assess its nature.



We sequenced new transcriptomes for Barnadesia, the lineage sister to all other Compositae, and four representatives of closely related families. Using a recently developed algorithm, MAPS, we analyzed nuclear gene family phylogenies for evidence of paleopolyploidy.



We found that the previously recognized Compositae paleopolyploidy is also in the ancestry of the Calyceraceae. Our phylogenomic analyses uncovered evidence for a successive second round of genome duplication among all sampled Compositae except Barnadesia.



Our analyses of new samples with new tools provide a revised view of paleopolyploidy in the Compositae. Together with results from a high density Lactuca linkage map, our results suggest that the Compositae and Calyceraceae have a common paleotetraploid ancestor and that most Compositae are descendants of a paleohexaploid. Although paleohexaploids have been previously identified, this is the first example where the paleotetraploid and paleohexaploid lineages have survived over tens of millions of years. The complex polyploidy in the ancestry of the Compositae and Calyceraceae represents a unique opportunity to study the long-term evolutionary fates and consequences of different ploidal levels.
Department of Ecology & Evolutionary Biology, University of Arizona, P. O. Box 210088, Tucson, Arizona 85721 USA msbarker@email.arizona.edu.
Michael S
MS
Barker
Department of Ecology & Evolutionary Biology, University of Arizona, P. O. Box 210088, Tucson, Arizona 85721 USA.
Zheng
Z
Li
Department of Ecology & Evolutionary Biology, University of Arizona, P. O. Box 210088, Tucson, Arizona 85721 USA.
Thomas I
TI
Kidder
Department of Ecology & Evolutionary Biology, University of Arizona, P. O. Box 210088, Tucson, Arizona 85721 USA.
Chris R
CR
Reardon
Department of Biology and Center for Genomics and Bioinformatics, Indiana University, Bloomington, Indiana 47405 USA.
Zhao
Z
Lai
Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Viçosa 36570-900, Viçosa, Brazil.
Luiz O
LO
Oliveira
Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, V6T 1Z4 Canada.
Moira
M
Scascitelli
Department of Biology and Center for Genomics and Bioinformatics, Indiana University, Bloomington, Indiana 47405 USA Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, V6T 1Z4 Canada.
Loren H
LH
Rieseberg
D019659:Asteraceae / Q000235:genetics*; D005075:Biological Evolution; D002874:Chromosome Mapping; D018745:Genome, Plant / Q000235:genetics*; D019684:Magnoliopsida / Q000235:genetics*; D010802:Phylogeny; D011123:Polyploidy; D059467:Transcriptome
asteraceae; calyceraceae; compositae; paleopolyploidy; polyploidy; transcriptome; whole genome duplication