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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

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.

Pages : 193-217
Année de publication : 2011
Revue : Telopea
N° de volume : 13(1-2)
Type : Article
Mise en ligne par : MBAYE Mame Samba