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The Sunda-Sahul exchange: functional and dynamic patterns

We showed that the two groups of contrasting biogeographic history in Australian rainforests, those of recent Southeast Asian origin (Sunda ancestry) and those of Sahul origin have distinct functional and distributional patterns.

We compared a large dataset consisting of 604 Sunda species and 795 Sahul species out of the 1,872 known Australian woody rainforest taxa. We asked whether Sunda migrants display functional characteristics that explain how they were able to arrive from the north and establish in Australia, and whether climate is a limiting factor for these migrant plant species that originate mostly from tropical climates.

Our results show that Sunda species display effective dispersal mechanisms (smaller fleshy palatable seeds enabling wider dispersal), as well as traits that enhance rapid establishment (such as lighter wood and shorter stature reflecting faster growth) and larger leaves (as expected from their tropical origins). The distribution of Sunda lineage is also influenced by interacting environmental and climatic factors and historical contingencies. Consequently, within our tropical forests the Sunda invasion was resisted within stable, communities saturated with Sahul lineages, and in the subtropical forests where climate acted as a selective filter.

Current research 

Outcomes of this study will form part of our investigation in the relative role of biogeographic history in structuring genetic diversity through time (using landscape genomic data), and the historical dynamics of rainforest populations.

Some of our relevant publications:

  1. Yap JYS, Rossetto M, Costion C, Crayn D, Kooyman R, Richardson J, Henry R (2017) Filters of floristic exchange: how traits and climate shape the invasion of Sahul from Sunda. Journal of Biogeography