Abstract Detail

Systematics Section / ASPT

Funk, Vicki A [1], Chan, Raymund [2].

The importance of outgroup selection and the use of unrooted networks in determining the phylogeny of the tribe Arctoteae (Compositae: subfamily Cichorioideae sensu stricto) using trnL-F, ndhF, and IT.

The Compositae (Asteraceae) is the largest flowering plant family (23,000 to 30,000) and its members are found throughout the world in both temperate and tropical habitats. The tribe Arctoteae (African Daisies) is a diverse and interesting group with a primarily southern African distribution (ca. 17 genera, 220 species); it is part of the monophyletic subfamily Cichorioideae s.s. Twenty-nine ingroup taxa and 16 outgroup taxa with a total of 130 sequences from three genetic markers, two from the chloroplast DNA (trnL-F and ndhF) and one from the nuclear genome (ITS), were used to evaluate the tribe and its proposed outgroups. Each molecular marker is examined separately, the chloroplast markers are examined together, and the data are combined. The data were analyzed with and without outgroups and problem taxa using parsimony and maximum likelihood methods. The analyses showed robust support for two outgroup clades and two main subtribes within the Arctoteae: Arctotineae and Gorteriinae. Support for the monophyly of the Arctoteae is weak. Within the Arctoteae, Berkheya, Haplocarpha, and Hirpicium are probably paraphyletic. Furthermore, Platycarpha most likely does not belong in the Arctoteae, and Heterolepis and the tribe Eremothamneae are within the Arctoteae but not within either of the two main subtribes. The study showed that the unusual taxa are of critical importance and that multiple outgroups evaluated in an iterative manner had pronounced effects on the relationships within the ingroup, not only on the position of the root. Finally, unrooted consensus trees and unrooted phylograms were found to be very useful in analyzing the data, allowing for the examination of the placement of taxa without the bias of a rooted tree.

1 - Smithsonian Institution, US National Herbarium, MRC166, Washington, DC, 20013-7012, USA
2 - University of Hawaii at Manoa, Botany, Manoa, Hawaii, 96822-2279, USA

Keywords:
Compositae
Asteraceae
Arctoteae
molecular systematics
South Africa.

Presentation Type: Paper
Session: 3-5
Location: Cottonwood B (Snowbird Center)
Date: Monday, August 2nd, 2004
Time: 9:00 AM
Abstract ID:898