ALBACH, DIRK C. 1*, PAMELA S. 1 SOLTIS, DOUGLAS E. 1 SOLTIS, AND RICHARD G. 2 OLMSTEAD. 1Department of Botany, Washington State University, Pullman, WA 99164-4238 and 2University of Washington, Department of Botany, Box 355325, Seattle WA 98195-5325. - Phylogenetic Analysis of the Asteridae s.l. Based on Sequences of Four Genes.
The Asteridae s.l., as circumscribed by Olmstead et al. (1992, 1993),
comprise about one-third of all angiosperm species. This clade
includes almost all sympetalous and iridoid-containing species, and
most species have unitegmic-tenuinucellate ovules. To elucidate the
evolution of these characters, we used a combined data set of
sequences from 18S rDNA, rbcL, ndhF and atpB with
a total of 7165 base pairs for 130 genera. The analysis resolved the
major lineages of Asteridae s.l., confirming the usefullness of large
data sets in phylogenetic systematics. Most of the taxa fall within
one of four major clades. The cornalean clade, comprising Cornaceae,
Nyssaceae, Hydrangeaceae, Loasaceae and Hydrostachyaceae, is sister to
the remaining genera. The ericalean-thealean clade clade consists of
taxa traditionally included in Ericales s.l., Primulales and Theales,
as well as Polemoniaceae and Balsaminaceae. The third clade comprises
the Asterales-Campanulales, Apiales and Dipsacales. The largest clade
includes Lamiales, Solanales, Boraginaceae and Gentianales. This
analysis allows us to infer patterns of evolution in the evolution of
the ovule and the diversification of iridoid biosynthesis.
Key words: Asteridae, molecular systematics