SYTSMA, KENNETH J., JEFFREY MORAWETZ*, J. CHRIS PIRES, AND CLIFFORD W. MORDEN. Department of Botany, University of Wisconsin, Madison, WI 53706; Department of Botany, University of Hawaii-Manoa, HI 96822. - Phylogeny of the Urticales based on three molecular data sets, with emphasis on relationships within Urticaceae.
The traditional Urticales (Ulmaceae, Celtidaceae, Cannabaceae,
Moraceae, Urticaceae, and Cecropiaceae) is one of the more
controversial orders in terms of family circumscriptions and both
inter- and intra-familial phylogenetic relationships. Recent
molecular evidence has clarified its position as a monophyletic
assemblage within a now expanded Rosales, with close relationships to
an unresolved group including Barbeyaceae, Dirachmaceae, Rhamnaceae,
and Elaeagnaceae. Although the Ulmaceae has now been demonstrated to
be sister to the rest of the urticalean lineage with both
morphological and molecular data, the circumscription and
relationships of the other families has remained unclear and
controversial. The majority of morphological analyses have concluded
either that (1) Celtidaceae, Cecropiaceae, Moraceae, and Urticaceae
should be combined as one family, or (2) at least Moraceae and
Urticaceae should be merged; the placement of Cannabaceae being
largely unknown. Analyses now based on rbcL, ndhF, and trnT-trnL
spacer sequences strongly support monophyly of each of the families
Moraceae and Urticaceae (with Ceropiaceae) and the polyphyletic nature
of Cecropiaceae with Poikilospermum at least imbedded within
Urticaceae. There is both strong sequence and indel support for the
placement of Cannabaceae within Celtidaceae. The different molecular
data are congruent in indicating polyphyly for the tribe Moreae and
the isolated position of Maclura within Moraceae, and that a number of
tribes within Urticaceae are either paraphyletic or polyphyletic.
Some of this discrepancy is due to the unusual placements of some
Hawaiian Urticaceae, most notably Touchardia. The robust molecular
results for major portions of the phylogenetic history of the
urticalean clade permit reinterpretation of morphological, anatomical,
and ecological features in the group as well as suggest changes in
classification and nomenclature.
Key words: Cannabaceae, classification, ndhF, trnT-trnL, Urticaceae, Urticales