NIEHAUS, KRISTI1, KHIDIR HILU1*, JOHN H. WIERSEMA2, and THOMAS BORSCH3. 1Dept. of Biology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061; 2USDA/ARS, Systematic Botany and Mycology Laboratory, Bldg. 011A, Beltsville Agricultural Research center (BARC-West), Beltsville, MD 20705-2350; 3Botanisches Institut und Botanischer Garten, Friedrich-Wilhelms-Universität Bonn, Germany. - Patterns of variation and evolution of Nymphaea odorata (Nymphaeaceae) assessed by molecular and morphological information.
Nymphaea odorata is the most common water lily species in
North America. Although a variety of infraspecific taxa have been
described, a recent classification accepts two subspecies: subsp.
odorata and subsp. tuberosa. The closest relative of
Nymphaea odorata is N. mexicana; the latter overlaps with
subspecies odorata from Texas to Florida. Subspecies
tuberosa occurs further north. To study patterns of variation and
speciation in N. odorata we have used information from
morphology and sequence data from ITS and trnT-F. Forty-three
populations from across the distribution of N.odorata and
four of N. mexicana were sampled. Forty morphological
characters were examined with univariate analysis, SAHN clustering,
and principle component analysis. Overall, morphology was highly
variable and no significant grouping by either subspecies or geography
was revealed. ITS sequences revealed the potential presence of
different paralogues and point to gene flow between and within the two
subspecies. Subspecies tuberosa seems to be characterized by a
different cpDNA haplotype. Parsimony and NJ analyses of nrDNA sequence
data excluding the apparently heterozygous individuals revealed two
clades, representing the subspecies. The results of the morphological
and molecular analysis are evaluated to infer phylogeographical
patterns and to explain the observed morphological variability.
Key words: evolution, morphologic variation, Nymphaea odorata, speciation