Abstract Detail

Systematics Section / ASPT

Saarela, Jeffery M. [1], Graham, Sean W. [2].

Phylogenetic relationships among the subfamilies of grasses (Poaceae) inferred from a large, multigene plastid data set.

Most molecular data sets indicate that Poaceae comprises several early-diverging lineages (subfamilies Anomochlooideae, Pharoideae and Puelioideae) plus two major clades: the ‘BEP’ clade (subfamilies Bambusoideae, Ehrhartoideae and Pooideae) and the ‘PACCAD’ clade (subfamilies Panicoideae, Arundinoideae, Centothecoideae, Chloridoideae, Aristidoideae and Danthonioideae). However, phylogenetic relationships among some of the major lineages within these two major clades remain poorly resolved or supported. To clarify these higher-order relationships, we surveyed ~13.5 kb of DNA sequence data spanning 17 chloroplast genes and associated noncoding regions from at least one representative of each subfamily (except Puelioideae) as well as representatives from several closely related families. Parsimony and Bayesian analyses confirm the phylogenetic positions of the early diverging lineages and robustly support the monophyly of the BEP and PACCAD clades. Within the BEP clade, subfamily Bambusoideae is moderately supported as the sister-group of subfamily Pooideae. Within the PACCAD clade, a sister-group relationship is strongly supported between subfamilies Centothecoideae and Panicoideae, while subfamilies Aristidoideae and Chloridoideae are moderately supported as a clade. We also discuss the identity of the sister group of the grasses and characterize variation in the rate of molecular evolution of the grasses and relatives.

1 - University of British Columbia, Botany Department, 3529-6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada
2 - University of British Columbia, UBC Botanical Garden and Centre for Plant Research, 6804 SW Marine Drive, Vancouver, British Columbia, V6T 1Z4, Canada

Keywords:
Poaceae
phylogenetics
molecular evolution
Bayesian
parsimony
chloroplast DNA
multigene analyses.

Presentation Type: Paper
Session: 20-6
Location: Cottonwood B (Snowbird Center)
Date: Monday, August 2nd, 2004
Time: 3:00 PM
Abstract ID:366