Vicariance biogeography uses most parsimonious areagrams in order to explain
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, leading
to areagrams showing area relationships not supported by geological data, and
plausible dispersal events might also be overlooked. By the use of the
software COMPONENT 2.0, Nothofagus phylogeny was
reconciled with the most parsimonious areagrams. Well-preserved fossils,
identified to subgenera, were optimised to the reconciled tree. Not all past
distributions were predicted by the analysis, and
Nothofagus has clearly been present in areas where it
cannot have been if strict vicariance is followed. It can therefore be
demonstrated that the biogeographic signal in Nothofagus
areagrams is incomplete, and that most parsimonious areagrams can be flawed.
Areagrams can be a useful tool in historical biogeography, but must be
scrutinised within a known geological context and not accepted uncritically as
alternative palaeogeographical hypotheses.
On biosignatures for Mars
