Rutaceae and Australia–New Caledonia biogeography

Project summary

Our aim is to determine the historical biogeographic links between Australia and New Caledonia based on a molecular phylogenetic analysis of the flowering plant family Rutaceae: discovering the pattern, timing and tempo of plant evolution across these areas.

Rutaceae includes rainforest and sclerophyllous species in New Caledonia and Australia. The family is an ideal group to discover general biogeographic patterns that will provide evidence of the geological history of fragments of Gondwana and the south-west Pacific region. The Australasian members of subfamily Rutoideae include 18 genera and 74 species in New Caledonia (being one of the five largest plant families there) and 36 genera and about 446 species in Australia. These are mostly woody shrubs and trees, occurring in habitats ranging from tropical rainforest to arid-zone shrubland.

Both vicariance and long-distance dispersal hypotheses have been postulated to account for Australia–New Caledonia links in Rutoideae. Links potentially dating to the vicariant separation of Australia and New Caledonia are postulated for taxa with relatively poor dispersal capacity, such as Zieria (Armstrong 2002), Medicosma (Hartley 1985), Boronella (Weston et al. 1984) and Neoschmidia. More recent long-distance dispersal between the two areas is postulated for some bird-dispersed groups, such as the fleshy-fruited genera Sarcomelicope, Acronychia (Hartley 1974), and Halfordia. In the latter two genera, the same species are shared between Australia and New Caledonia, which can be argued is evidence of relatively recent connections between populations in the two areas. The exact number and the nature of all Australia–New Caledonia links in Rutoideae are not clear, and the primary aim of this project is to better understand them by applying modern molecular phylogenetic and biogeographic methods.

This study will result in the first comprehensive molecular phylogeny of a major component of the Australasian flora, the family Rutaceae, and improve our understanding of the evolution of Australia's flora.

Project team

  • David Cantrill (Royal Botanic Gardens Melbourne)
  • Pauline Ladiges (School of Botany, The University of Melbourne)
  • Mike Bayly (School of Botany, The University of Melbourne)
  • Gareth Holmes (Royal Botanic Gardens Melbourne)
  • Paul Forster (Queensland Herbarium)
  • Jérôme Munzinger (Herbarium of Nouméa)

Support

  • ARC Linkage Grant

References

Armstrong, J.A. (2002). Zieria (Rutaceae): a systematic and evolutionary study.Australian Systematic Botany 15, 277–463.

Hartley, T.G. (1974). A revision of the genus Acronychia (Rutaceae). Journal of the Arnold Arboretum 55, 469–523, 525–567.

Hartley, T.G. (1985). A revision of the genus Medicosma (Rutaceae). Australian Journal of Botany 33, 27–64.

Weston, P.H., Carolin, R.C. and Armstrong, J.A. (1984). A cladistic analysis ofBoronia Sm. and Boronella Baill. (Rutaceae). Australian Journal of Botany 32, 187–203.

Publications

Ladiges, P.Y. and CantrillD.J. (2007). New Caledonia–Australian connections: biogeographic patterns and geology. Australian Systematic Botany 20, 383–389.