Using Sequences of rbcL to Study Phylogeny and Biogeography of Nothofagus Species

Abstract

Sequences of rbcL for 23 species of Nothofagus and three of Fagus have been determined and analysed to form phylogenetic trees. The two genera are well separated. The species of Nothofagus separate into lineages which correspond exactly with the subgenera recently defined on morphological grounds. The rate of evolution of the four subgenera is shown to be statistically the same and, using a reference date from palaeobotany, is found to be one nucleotide change in 6 Ma. This rate is used to derive the ages of the common ancestors of species in subgenera and it is tentatively concluded that intercontinental dispersal was possible in the early stages of the evolution of the genus.