KIM, SEUNG-CHUL1*, KAREN LUNDY1, and ARNOLDO SANTOS-GUERRA2. 1Department of Botany and Plant Sciences, University of California, Riverside, CA 92521; 2Jardin de Aclimatacion de La Orotava, Calle Retama Num. 2, E-38400, Puerto de la Cruz, Tenerife, Canary Islands, Spain. - Phylogenetic relationships in the woody Sonchus alliance (Asteraceae) based on chloroplast DNA noncoding sequences.
The woody Sonchus alliance (Asteraceae: Lactuceae) in the Macaronesian
islands is comprised of 19 species of woody Sonchus and five closely
related genera and has been regarded as an outstanding example of
adaptive radiation among angiosperms. Previous phylogenetic study
based on ITS sequences of nrDNA demonstrated the monophyly of the
entire alliance and suggested several phylogenetic relationships among
the species within the alliance. Further, the ITS phylogeny suspected
the placement of several Sonchus species in the Taeckholmia clade due
to ancient hybridization and subsequent fixation of the Taeckholmia
type ITS sequences. The cpDNA nocoding regions, trnL intron, trnT-L
intergenic spacer, and trnL-F intergenic spacer, were sequenced to
independently explore relationships within the alliance and also to
understand the role of hybridization during the adaptive radiation of
the alliance. The cpDNA phylogeny shows low resolution compared to the
ITS phylogeny and reveals many different relationships within the
alliance. This discordance could be the result of ancient
hybridization and subsequent chloroplast capture and further suggests
that hybridization appears to have been much more pervasive in the
Sonchus alliance than previously suspected.
Key words: adaptive radiation, trnT-L-F, woody Sonchus alliance. Macaronesia