Freshwater paths across the ocean : molecular phylogeny of the frog Ptychadena newtoni gives insights into amphibian colonization of oceanic islands

摘要: Aim  Amphibians are a model group for studies of the biogeographical origins salt-intolerant taxa on oceanic islands. We used Gulf Guinea islands to explore island endemism one species frog, and this gain insights into potential colonization mechanisms. Location  Sao Tome Principe, two four major in Guinea, West Africa, truly have an exceptionally high biodiversity. Methods  Mitochondrial DNA is test endemic status frog from compare it with congeneric tropical Africa. Existing data surface currents, salinity, atmospheric circulation bird migration summarized address hypotheses concerning mechanisms. Results  The Ptychadena newtoni (Bocage) supported here by mitochondrial sequences, analysis other molecular indicates that East African close mascareniensis (Dumeril Bibron) its nearest relative. refute possibility population was anthropogenically introduced, favour natural dispersal mechanism. Main conclusions  With six frogs caecilian, harbour diverse amphibian fauna. Five these appear their closest relatives Insufficient evidence exists transportation storms, birds or rafts alone. However, we propose synergy rafting, favourable currents reduction salinity waters. Catastrophic events, wet periods climatic history, could allow freshwater paths open far enough enable continental flora fauna reach isolated