Abstract Detail

Systematics Section / ASPT

Bell, Hester L. [1], Columbus, J. Travis [1].

Molecular phylogenetics of the Monanthochloinae (Eragrostideae, Chloridoideae, Poaceae) based upon ITS (nrDNA) and trnL-F (cpDNA).

Within the grasses, the subfamily Chloridoideae (~145 genera and ~1400 species) forms a strongly supported group. Hilu and Alice established that the Chloridoideae can be divided into three clades; A includes Eragrostis, B includes Sporobolus, C includes Bouteloua and Muhlenbergia as well as many smaller genera (such as Aeluropus, Monanthochloë, and Reederochloa). Our study is focused on the position of members of the subtribe Monanthochloinae (sensu Clayton and Renvoize) that contains Aeluropus, Allolepis, Distichlis, Jouvea, Monanthochloë, Reederochloa, and Swallenia. All species in the Monanthochloinae are rhizomatous perennials occurring in the New World except that Aeluropus is found in the Old World and one species of Distichlis occurs in Australia. Most species in the subtribe are dioecious except for Aeluropus and Swallenia that both have hermaphroditic flowers. Results based on separate and combined analyses of ITS (nrDNA) and trnL-F (cpDNA) sequences indicate that all members of the Monanthochloinae belong in Clade C. Within Clade C, Distichlis, Monanthochloë, and Reederochloa form a clade (D/M/R) in both phylogenies. The relationships of all other genera in the subtribe lack jackknife support above 70%. In the ITS analysis, D. distichlophylla and D. palmeri are nested within D. spicata, furthermore D. australis, D. humilis, D. laxiflora, and D. scoparia, four South American species, are more closely related to Reederochloa and Monanthochloë than to D. spicata. The D/M/R clade is well supported in the trnL-F analysis but the positions of other genera in the Monanthochloinae are not resolved by this marker. Overall, the combined analyses support Clade C as distinct from the Eragrostis (A) and Sporobolus (B) clades but does not resolve many internal nodes. Strategies to improve resolution of relationships within Clade C will be discussed.

1 - Rancho Santa Ana Botanical Garden, 1500 North College Avenue, Claremont, California, 91711-3157, USA

Keywords:
Poaceae
Eragrostideae
Chloridoideae
Monanthochloinae
molecular phylogeny.

Presentation Type: Paper
Session: 20-7
Location: Cottonwood B (Snowbird Center)
Date: Monday, August 2nd, 2004
Time: 3:15 PM
Abstract ID:656