Systematics Section / ASPT
Mathews, Katherine Gould .
Phylogeny of Sabatia and the distribution of floral polymery.
The objectives of this study are to determine evolutionary relationships among the species of Sabatia (Gentianaceae, Chironieae) using a relatively quickly-evolving chloroplast DNA (cpDNA) gene region, the trnD-trnT spacer (ca. 1 kb), and to use a phylogenetic hypothesis to understand the distribution of floral polymery in this group. Sabatia is an annual to biennial, herbaceous flowering plant genus that contains approximately 17 species distributed in eastern North America and the West Indies. It is primarly a coastal plain group with many of the species found in wetland habitats, mainly in freshwater but also tidal marshes. While most species of Sabatia (as well as most gentians) have five petals, six species have evolved an increase in petal number (typically 10-12 petals), making the flowers of these species relatively large and conspicuous. Polymerous flowers have also evolved in several other genera of Gentianaceae, so this character state may be homoplastic and influenced by selection. A molecular phylogeny will be estimated using parsimony and the resulting hypotheses used to infer how many times floral polymery has evolved in Sabatia. Since relatively conserved cpDNA gene regions (matK, trnL intron) have not proven to be useful for resolving species-level relationships in Sabatia and related genera, the phylogenetic utility of trnD-T will be discussed.
1 - Western Carolina University, Department of Biology, 132 Natural Science Building, Cullowhee, North Carolina, 28723, USA
Presentation Type: Paper
Location: Cottonwood A (Snowbird Center)
Date: Monday, August 2nd, 2004
Time: 1:15 PM