Historical Biogeography and Floristic Exchange in Southeast Asia

The historical biogeography of Southeast Asia has been shaped by a dynamic interplay of plate tectonics, sea‐level fluctuations and climatic shifts since the Cenozoic. The collision of the Eurasian, Indo‐Australian and Pacific plates forged island arcs and continental shelves, notably Sundaland, Wallacea and Sahul, which intermittently connected and isolated floras. Repeated glacial and interglacial cycles drove sea levels up and down, opening land bridges for range expansions and then severing them to generate endemic lineages. This alternating connectivity fostered pulses of dispersal, vicariance and in situ diversification, resulting in one of the richest plant assemblages on Earth. Key floristic exchange events include westward incursions of Asian wet‐forest taxa into New Guinea and Australia, eastward colonisations of Australian lineages into Malesian mountains, and long‐distance dispersals across oceanic barriers into the Pacific islands. These processes have produced a mosaic of centres of endemism and phylogenetic diversity that underpins conservation priorities and informs models of tropical ecosystem resilience under future environmental change.

Research from Nature Portfolio

A seminal meta-analysis has introduced a quantitative framework to assess temporal pulses of biotic interchange by mapping the rate of documented dispersal events over tens of millions of years. This approach revealed that exchanges between the Indian subcontinent and mainland Asia after the Eocene collision were episodic rather than constant, with peaks corresponding to periods of tectonic uplift, monsoon intensification and shifts in palaeohydrology. By integrating time‐calibrated phylogenies and dispersal event counts, the study highlights the importance of irregular environmental forcing in driving major floristic dispersal waves, challenging previous notions of steady colonisation following land‐bridge formation.

Historical Biogeography and Floristic Exchange in Southeast Asia publication trend

The graph below shows the total number of articles in historical biogeography and floristic exchange in southeast asia across all publications each year (not limited to Nature Index journals).

Technical terms

Historical biogeography: The study of how geological and climatic history shapes the spatial distribution of organisms over time.

Floristic exchange: The movement and integration of plant lineages between distinct geographic regions.

Biotic interchange: The dispersal and establishment of organisms following the connection of previously isolated landmasses.

Phylogeography: The analysis of the historical processes that have shaped the geographic distribution of genetic lineages.

Wallace’s Line: A biogeographical boundary separating Asian and Australian faunal and floral provinces.

Dispersal–extinction–cladogenesis (DEC) model: A likelihood framework used to reconstruct ancestral geographic ranges by accounting for dispersal, local extinction and speciation events.

Endemism: The condition of species being restricted to a defined geographic area.

Palaeoenvironmental drivers: Past environmental factors, such as climate oscillations or tectonic events, that influence species distribution and diversification.

References

1. Biotic interchange between the Indian subcontinent and mainland Asia through time. Nature Communications (2016).
2. From earthquakes to island area: multi‐scale effects upon local diversity. Ecography (2024).
3. Predominant colonization of Malesian mountains by Australian tree lineages. Journal of Biogeography (2019).
4. Sunda–Sahul floristic exchange and pathways into the Southwest Pacific: New insights from wet tropical forest trees. Journal of Biogeography (2023).