Evolution and biogeography of the austral genus Phyllocladus (Podocarpaceae)


Steven J. Wagstaff, Allan Herbarium, Landcare Research, PO Box 69, Lincoln 8152, New Zealand.
E-mail: wagstaffs@landcareresearch.co.nz


Aim  To infer evolutionary relationships within the genus Phyllocladus and among its close relatives by phylogenetic analysis of DNA sequences. Interpret the inferred relationships in association with the fossil record to examine the origin and diversification of the genus.

Location  Australasia.

Methods  Phylogenetic analyses of rbcL, matK and internal transcribed spacer (ITS) sequences representing all of the extant species of Phyllocladus and a selection of outgroups from Podocarpaceae and Araucariaceae.

Results  The rbcL and matK sequences exhibit little variation within Phyllocladus, but ally its members to Podocarpaceae although its immediate sister remains unclear. The ITS sequences resolve all five species of Phyllocladus and two intraspecific ecotypes of P. alpinus.

Main conclusions Phyllocladus forms a distinct lineage that diverged early in the evolutionary history of Podocarpaceae. The fossil record indicates that the genus was more widely distributed and morphologically diverse during the early Tertiary than at present. Although of Mesozoic origin, the level of sequence variation within Phyllocladus suggests that the extant species radiated during the late Tertiary c. 6.3 ± 0.9 Ma. New Zealand is the present centre of species diversity.