Abstract Detail

Systematics Section / ASPT

Lee, Chunghee [2], Kim, Seung-Chul [2], Santos-Guerra, Arnoldo [1].

The phylogeny of the woody Sonchus alliance (Asteraceae: Sonchinae) based on chloroplast and low copy nuclear gene sequences.

The woody Sonchus alliance is one of the largest diverse endemics (6 genera and approximately 31 species) and represents a premiere example of adaptive radiation in Macaronesia. The previous studies have shown that the woody Sonchus alliance in the Macaronesian Islands is monophyletic and radiated recently. Due to its recent radiation on the islands, the phylogenetic relationships among the members within the alliance were poorly resolved. Here we sequenced two low copy nuclear genes (i.e., Gpat and G3pdh) and ca. 4500 bp of chloroplast coding and noncoding regions. The cpDNA phylogenys is somewhat poorly resolved within the alliance, but it suggests that four segregate genera (i.e., Lactucosonchus, Chrysoprenanthes, Babcockia, and Sventenia) radiated early, followed by major radiation of subg. Dendrosonchus sensu Aldridge. It also suggests that Sonchus tuberifer and few other taxa of Dendrosonchus radiated first within the major radiation of subg. Dendrosonchus sensu Aldridge. However, the current cpDNA sequence alone did not provide sufficient resolution within subg. Dendrosonchus sensu Aldridge. Two low copy nuclear genes, G3pdh and Gpat, seem to provide sufficient resolution within the woody Sonchus alliance. However, the phylogenies based on two nuclear loci are different drastically from the ITS tree, especially the positions of four segregate genera and Sonchus tuberifer. In addition, relationships among taxa within the subg. Dendrosonchus sensu Aldridge differed significantly. Overall, the preliminary cpDNA phylogeny is similar to the ITS tree and is significantly different from the preliminary G3pdh and Gpat trees. Several major incongruences among the phylogenies and their possible explanations will be discussed.

1 - Jardin de Aclimatacion de la Orotava, Calle Retama Numero 2, Puerto de la Cruz, Teneri, Canary Islands, E-38040, Spain
2 - University of California, Botany and Plant Sciences, Riverside, California, 92521

Keywords:
woody Sonchus alliance
adaptive radiation
Macaronesian islands
ITS
cpDNA
low copy nuclear genes.

Presentation Type: Paper
Session: 3-10
Location: Cottonwood B (Snowbird Center)
Date: Monday, August 2nd, 2004
Time: 10:15 AM
Abstract ID:875