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Abstract Detail


Systematics Section

Grass Phylogeny Working Group II,  [1].

Relationships among the subfamilies of grasses (Poaceae).

The phylogeny of the grass family has received a great deal of attention, and published data to date have supported twelve well-supported clades that are named as subfamilies. The three smallest subfamilies are consistently supported as successive sisters to the remainder, which are divided into the BEP clade (Bambusoideae, Ehrhartoideae and Pooideae) and the PACMAD clade (Panicoideae, Arundinoideae, Chloridoideae, Micrairoideae,Aristidoideae and Danthonioideae). Although both the BEP clade and the PACMAD clade are strongly supported,relationships among their respective subfamilies are unresolved. Phylogenetic analyses using one or two genes have found almost all possible relationships among the subfamilies, and the results are often highly sensitive to taxon sampling. The PACMAD clade is of particular interest here because it contains at least 17 origins (and possible reversals)of C4 photosynthesis; however, determining the precise number and phylogenetic position of these changes requires a resolved and robust phylogeny. The GPWGII was formed in 2010 specifically to resolve the PACMAD phylogeny as a crucial step towards investigating C4 evolution. By using data available in NCBI and supplementing it with extensive unpublished data from each of our lab groups, we were able to assemble a dataset of 540 taxa with sequences from the chloroplast loci rcbL, ndhF and matK. Additional sequences were then produced to fill in gaps in the matrix and reduce missing data to only 7%. Within the PACMAD clade, our data support the position of Aristidoideae as sister to the other subfamilies, and Panicoideae as the next diverging clade. The remaining four clades have the relationship ((chloridoid,danthonioid),(arundinoid, micrairoid)). Although not a focus of this particular project, we also resolved the BEP clade as ((bambusoid, pooid), oryzoid). Our taxon sampling focused particularly on Panicoideae, for which we included nearly all currently recognized genera. Our results are consistent with previous single-gene studies, but with better resolution and stronger support.

Broader Impacts:


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Keywords:
PACMAD
Panicoideae
Chloridoideae
Arundinoideae
Danthonioideae
Micrairoideae
Aristidoideae
C4 photosynthesis.

Presentation Type: Oral Paper:Papers for Sections
Session: 44
Location: Lindell A/Chase Park Plaza
Date: Wednesday, July 13th, 2011
Time: 8:30 AM
Number: 44001
Abstract ID:398


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