Barrett, Craig , Davis, Jerrold , Leebens-Mack, Jim , Stevenson, Dennis , Conran, John , Zomlefer, Wendy .
Plastid genomes and deep relationships among the commelinid monocots.
The commelinid monocots comprise the orders Arecales, Commelinales, Poales (sensu APGIII), Zingiberales, plus the unplaced family Dasypogonaceae. These major monocot groups contain many ofthe most economically and ecologically important species, encompass enormous morphological diversity, and are supported as a clade by anatomical characters and molecular phylogenetic analyses. However, previous studies support conflicting relationships among thesegroups. Even in recent whole-plastome analyses (with sampling largely focused on Poales) areas of conflict still exist,suggesting the need for closer investigation of relationships and support. We have increased sampling of non-Poalean commelinid plastomes to investigate support at the deepest nodes, using Illumina short-read sequencing of whole plastomes. Analyses of 46 monocot taxa and 83 plastid genes (over 20,000 informative characters) recover the same relationships among major commelinid groups as in some previous plastome studies, with robust support, regardless of reconstruction method (parsimony vs. likelihood). Arecales are sister to Dasypogonaceae, and this clade is sister to ((Zingiberales, Commelinales) Poales). However, substantial conflict among genes is evident: gene subsets based on genomic region (large single copy, small single copy, inverted repeat) recover different relationships. When genes were ranked in order of decreasing numbers of informative characters, cumulative phylogenetic analyses indicated continued fluctuation in support, even as very small genes were added to a nearly complete matrix. This was contrary to the hypothesized pattern of stabilization of support values as genes with fewer informative characters are sequentially added. Tests of alternative topologies among the major commelinid groups suggested that the data were not decisive enough to reject all possibilities. Thus, this study provides clues to the limits of the plastid genome for resolving deep relationships among the commelinid monocots. A closer investigation of relationships in two emblematic tropical commelinid orders (Arecales and Zingiberales) was also undertaken. Analyses of plastid genomes representing all five palm subfamilies are largely in agreement with previous multigene studies,here with extremely high support, including the placement of the monotypic Nypa fruticans as sister to ((Coryphoideae(Ceroxyloideae, Arecoideae)). Analysis of representatives of each of the eight families of Zingiberales resulted in a largely resolved and highly supported tree, but with novel relationships near the base, namely among Musaceae and Heliconiaceae. The plastid genome represents one version of monocot evolutionary history, and here displays powerful capabilities as well as limitations for phylogenetics.
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1 - Cornell University, Department of Plant Biology, 412 Mann Library Building , Ithaca, NY, 14853, USA
2 - CORNELL UNIVERSITY, PLANT BIOLOGY AND L.H. BAILEY HORTORIUM, 412 MANN LIBRARY BUILDING, ITHACA, NY, 14853-4301, USA
3 - University Of Georgia, 4503 Miller Plant Sciences, Athens, GA, 30602, USA
4 - THE NY BOTANICAL GARDEN, 2900 SOUTHERN BLVD, BRONX, NY, 10458-5126, USA, 718/817-8632
5 - The University Of Adelaide, ACEBB EEB/EES, Benham Bldg, DX650 312, Adelaide, N/A, SA 5005, Australia
6 - University Of Georgia, Department Of Plant Biology, 2052 Miller Plant Sciences Building, 120 Carlton Street, Athens, GA, 30602, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Delaware B/Hyatt
Date: Tuesday, July 10th, 2012
Time: 3:45 PM