ZHANG, XIAOYAN AND SHAUN M. MCELLIN.* ( Department of Forestry, Michigan State University, East Lansing, MI 48824 and Wuhan Institute of Botany, Academia Sinica, Wuhan 430074, Hubei, P. R. China; * Department of Life Science, New Mexico Highlands University, Las Vegas, NM 87701). - The reconstruction and comparison of phylogenetic trees of the order Nymphaeales based on morphological and molecular data.
In this study, cladistic analyses were carried out to reveal the
phylogenetic relationships among the 10 genera of the waterlilies
order Nymphaeales sensu lato . Twenty-four morphological,
anatomical, and palynological characters and a molecular data set of
an 1183-base-pair (bp) portion of the chloroplast gene rbcL sequences
were extracted from a number of previously published references and
databases. Three types of methods, i.e., maximum parsimony, character
compatibility, and maximum likelihood methods were used for
reconstructing phylogenetic trees. Eleven phylogenetic trees based on
morphological and molecular data were generated by using three
computer program packages, i.e., PHYLIP 3.5c, PAUP 3.1.1, and MacClade
3.04, and related algorithms. In order to determine the degrees of
consistency between these resulting phylogenetic trees and some
exisiting classification systems of Nymphaeales such as Cronquist
(1981) , a generalized method for tree-comparison based on subtree
similarity was applied. This analysis resulted in elucidating two
trees (one morphological and one molecular) that showed the greatest
similarity in comparisons among the classifications. From the results
of the present cladistic analyses based on both morphological and
molecular data and the most similar trees, the phylogenetic status of
each genus and their relationships were clarified as follows: 1)
Nelumbo and Barclaya are two distinct taxa and can be
recognized as two families each containing a single genus. 2)
Nelumbo is presumed to have originated from an ancestral stock of
the order; 3) Ceratophyllum has a relatively close
phylogenetic relationship with Cabomba and Brasenia
(Cabombaceae sensu Cronquist; and 3) Nuphar and the
remaining genera constitute a monophyletic group in the Nymphaeaceae
sensu stricto , that disagrees with the concept of
Nupharaceae in some classifications such as Li (1955).
Key words: cladistics, molecular data, morphological data, Nymphaeales, phylogenetic tree