BOEREMA, DAVID1, TIMOTHY M. EVANS1*, and GREGORY K. BROWN2. 1Biology Department, Hope College, Holland, MI 49423-9000; 2Department of Botany, University of Wyoming, Laramie, WY 82071. - Phylogenetic relationships in O÷nopsis (Asteraceae) based on DNA sequences from three spacer regions.
O÷nopsis is a monophyletic genus consisting of five species
distributed mainly in central and eastern Wyoming and Colorado. The
plants are herbaceous perennials that tend to grow on alkaline soils.
All members of the genus are primary selenium indicators, and appear
to be obligatory seleniophiles. The purpose of this study was to
determine phylogenetic relationships among species of the genus
O÷nopsis using DNA sequence data from two chloroplast
intergenic spacers (trnL-trnF and
psbA-trnH) and the nuclear ribosomal internal
transcribed spacers (ITS). Sequence variation was lowest in the
trnL-trnF spacer and greatest in the
psbA-trnH region. The total data phylogeny placed O.
multicaulis sister to the rest of the genus. O. foliosa
var. foliosa and O. foliosa var. monocephala were
placed in separate clades, in disagreement with morphology-based
phylogenies. Low bootstrap and decay values indicate a low amount of
divergence among sequences, suggesting a relatively recent origin for
Key words: Asteraceae, ITS, O÷nopsis, psbA-trnH, trnL-trnF