Systematics Section / ASPT
Brunsfeld, Steven J. , Anttila, Carina K. .
Complexities in the Phylogeny of Salix (Salicaceae)..
Salix is a large and important group of temperate woody plants with a wide distribution in the northern hemisphere. Evolutionary relationships within the group are still poorly understood, with most of our ideas based on assumptions about traditional morphological characters and limited genetic data. As part of a larger study employing molecular genetic data to explore phylogeography and hybridization in the group, we have also gained two independent hypotheses of phylogenetic relationships. Trees obtained from analysis of chloroplast matK and nuclear ITS sequences show substantial incongruence and include many deviations from traditional taxonomic concepts. The major subgenera, Salix and Vetrix, are recognizable, but many species have differing placements that provide insights into evolutionary processes and change assumptions about the taxonomic value of some morphological characters. For example, sect. Longifoliae is part of a subg. Vetrix clade in the ITS tree, in agreement with crossing studies. However, this section lies within a well-supported matK clade that corresponds with subg. Salix, a placement common to many classifications. Neither data set provides support for the recognition of a subg. Chamaetia, a group composed primarily of dwarf shrubs. Both data sets verify that the genus Chosenia is a morphologically divergent part of Salix subg. Vetrix. These analyses add evidence to the suggestion that hybridization has played a major role in the evolution of the genus, and provide many insights into morphological evolution. The results provide a wealth of hypotheses worth testing using genetic and other approaches.
1 - University of Idaho, Department of Forest Resources, Moscow, Idaho, 83844, USA
2 - University of Joensuu, Biological Station, Joensuu, 80101, Finland
Presentation Type: Paper
Location: Cottonwood B (Snowbird Center)
Date: Tuesday, August 3rd, 2004
Time: 10:15 AM