Ancestral area analysis of Nothofagus (Nothofagaceae) and its congruence with the fossil record

The evolutionary centre of origin of Nothofagus (Nothofagaceae) remains an open question. Competing hypotheses suggest either a South American or Aust ralasian source area for Nothofagus. Antarctica, once part of Gondwana and densely vegetated in the Cretaceous, was certainly important for the divers ification of the genus but cannot be included in current modelling due to i ts lack of extant species. By using Bremer s (1992), Ronquist s (1994) and Hausdorf s (1998) methods, all based on cladistic philosophy, analyses of t he modern areas of endemism being part of the ancestral area of Nothofagus were undertaken. Southern South America was distinctly identified as the li kely ancestral area by Bremer's and Hausdorf s methods. This result is supp orted by the current fossil record. Ronquist s method was not decisive and yielded ambiguous results, suggesting a larger, combined ancestral area. Th ese results do not favour Australasia, or parts thereof, being an important area for Nothofagus origin. Bremer's and Hausdorf s methods identified New Zealand as the second most plausible source area, a result partly supporte d by the fossil record.