SOROS, CONNIE L.*, DONALD H. LES, MICHAEL L. MOODY, AND USHER POSLUSZNY. Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT USA 06269-3043 and Department of Botany, University of Guelph, Guelph, ON CANADA N1G 2W1. - Phylogenetic relationships in the Hydrocharitaceae.
A phylogenetic analysis of Hydrocharitaceae was conducted using data
from the internal transcribed spacers (ITS-1;2) of the nuclear
ribosomal genes, the chloroplast gene IrbcL and the flanking
introns of the chloroplast matK gene. The aquatic,
monocotyledonous Hydrocharitaceae consist of 17 genera which are
highly variable in habitat, pollination and morphology. Numerous
convergences and reduced vegetative and reproductive structures make
it difficult to interpret morphological characters for phylogenetic
analysis. Our combined data set showed high congruency with results
published previously using rbcL data alone, or a combination
of rbcL and matK (coding region) data. The combined
molecular data consistently show a monophyletic origin for the family.
Other results include the monophyly of seagrass genera
(Enhalus, Halophila and Thalassia), a
possible sister group relationship of Najadaceae and Hydrocharitaceae,
and several well-supported monophyletic clades within the family.
Currently, morphological and developmental characters within the
Hydrocharitaceae are being investigated to supplement the molecular
data for further investigation of relationships.
Key words: Hydrocharitaceae, ITS, matK, morphology, phylogeny, systematics