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Towards a complete species tree of Nymphaea: shedding further light on subg. Brachyceras and its relationships to the Australian water-lilies

2011; National Herbarium of NSW; Volume: 13; Issue: 1-2 Linguagem: Inglês

10.7751/telopea20116014

2200-4025

Thomas Borsch, Cornelia Loehne, Mame Samba Mbaye, John H. Wiersema,

Ecology and Vegetation Dynamics Studies

The water-lily genus Nymphaea exhibits a worldwide distribution with an estimated number of more than 50 extant species.Recent phylogenetic analyses resolved three major lineages, a subg.Brachyceras-subg.Anecphya clade, also including Nymphaea ondinea, a subg.Hydrocallis-subg.Lotos clade, and the temperate subg.Nymphaea as a third clade.This study extends the taxon sampling for Brachyceras, previously the least understood subgenus.Maximum Parsimony and Bayesian analysis of nrITS sequence data depict a monophyletic subg.Brachyceras-clade and show a New World clade to be nested within African taxa.Plastid trnT-trnF sequence data are less conclusive.A middle Miocene origin is inferred for the New World Brachyceras lineage that must have dispersed out of Africa either via a Beringian migrational route or through immediate long distance dispersal.Within subg.Brachyceras, the West African individuals of Nymphaea guineensis form a distinct clade in both nuclear and plastid trees to which the Madagascan Nymphaea minuta is sister.Central and East African Brachyceras species appear well separated, suggesting a separating effect of the Dahomey gap to the evolution of these species.ITS sequences are more powerful in identifying Nymphaea species than trnT-trnF sequences.Nevertheless, about 15% of the known species remain to be sampled for a complete molecular tree of water-lilies.This also requires sampling of multiple populations in order to discover entities with a common evolutionary history and distinct molecular and morphological characters.