Most parsimonious areagrams versus fossils: the case of Nothofagus (Nothofagaceae)

Vicariance biogeography uses most parsimonious areagrams in order to explai n biogeographic patterns. One notion is that areagrams convey biogeographic information to the extent that alternative palaeogeographic hypotheses are suggested. However, extinctions may distort biogeographic information, lea ding to areagrams showing area relationships not supported by geological da ta, and plausible dispersal events might also be overlooked. By the use of the software COMPONENT 2.0, Nothofagus phylogeny was reconciled with the mo st parsimonious areagrams. Well-preserved fossils, identified to subgenera, were optimised to the reconciled tree. Not all past distributions were pre dicted by the analysis, and Nothofagus has clearly been present in areas wh ere it cannot have been if strict vicariance is followed. It can therefore be demonstrated that the biogeographic signal in Nothofagus areagrams is in complete, and that most parsimonious areagrams can be flawed. Areagrams can be a useful tool in historical biogeography, but must be scrutinised withi n a known geological context and not accepted uncritically as alternative p alaeogeographical hypotheses.