Phylogenetic analysis of Nymphaeales using fast-evolving and noncoding chloroplast markers
2007
Löhne, Cornelia | Borsch, Thomas | Wiersema, John H.
The Nymphaeales (water-lilies and relatives) represent one of the earliest branching lineages of angiosperms and comprise about 70 aquatic species. Here, we present a comprehensive study of phylogenetic relationships within the Nymphaeales from a dataset containing 24 representatives of the order, including all currently recognized genera and all subgenera of the genus Nymphaea, plus 5 outgroup taxa. Nine different regions of the chloroplast genome - comprising spacers, group II introns, a group I intron, and a protein coding gene - were analysed. This resulted in a character matrix of 6597 positions and an additional 369 characters obtained from coded length mutations. Maximum parsimony and Bayesian analyses of the complete dataset yielded congruent, fully resolved and well-supported trees. Our data confirm the monophyly of the Cabombaceae but do not provide convincing support for the monophyly of Nymphaeaceae with respect to Nuphar. Moreover, the genus Nymphaea is inferred to be paraphyletic with respect to Ondinea, Victoria and Euryale. In fact, the Australian endemic Ondinea forms a highly supported clade with members of the Australian Nymphaea subgenus Anecphya. In addition, Victoria and Euryale are inferred to be closely related to a clade comprising all night-blooming water-lilies (Nymphaea subgenera Hydrocallis and Lotos). An experimental approach showed taxon sampling to be of influence on the nodes reconstructed in core Nymphaeaceae. The results underscore that more diverse genera, if not clearly known to be monophyletic, should be represented by all major lineages.
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