DONOGHUE, MICHAEL J.* and CHARLES D. BELL. Department of Ecology and Evolutionary Biology, Yale University, P. O. Box 208105, New Haven, CT 06520-8105. - Character evolution in Dipsacales.
Our phylogenetic analyses of Dipsacales, based on 6,500 base pairs of
chloroplast DNA, provide a well resolved, well supported phylogenetic
hypothesis for the major lineages. An additional dataset from the internal transcribed spacer (ITS)
region of the nuclear genome provides additional support for several
relationships that were not as strongly supported by the chloroplast
data alone (e.g., Heptacodium as sister to Caprifolieae). A
combined analysis yields a tree in which nearly every branch is
supported with a bootstrap value of 100%. This provides a solid
backbone for the assembly of a supertree that draws together analyses
of included clades based on a variety of data types. The result is a
tree of about one quarter of the more than 1,000 species of
Dipsacales, which well represents all of the major lineages. Using
this framework we analyze trends in character evolution, including
vegetative and reproductive traits. While the direction of evolution
is easily determined for many characters (e.g. woody to herbaceous
habit; simple to compound leaves; five stamens to four, and then
fewer), the interpretation of others (e.g., number of carpels; corolla
shape; nectary type, pollen morphology) depends critically on
attaining better knowledge of the relationships of Dipsacales within
Asteridae.
Key words: character evolution, Dipsacales, supertrees