The Ancient Journey of African Tropical Trees to Southeast Asia

From this well-document report:

'The rainforests of Southeast Asia comprise 15 percent of the world’s tropical rainforests and are spread across Indonesia, the Malay peninsula, which includes Malaysia, Thailand and Myanmar, and Laos and Cambodia. Boasting four out of 25 of the world’s biodiversity hotspots, the region hosts a treasure trove of species, including critically endangered, charismatic animals such as orangutans and rhinoceros. In 2020, scientists discovered 224 new species in the Greater Mekong region, which included 155 species of plants.

'Southeast Asian lowland and hill rainforests are dominated by a family of pantropical trees called Dipterocarpaceae represented by more than 400 species. Dipterocarps —meaning ‘two-winged fruits’ — are valuable for their timber. But the origin of these slow-growing, economically-important trees has remained a mystery due to the lack of fossil evidence of their early history.

'An international team of researchers studied newly discovered fossilised pollen to reveal that dipterocarps in Southeast Asian rainforests originated thousands of miles away in tropical Africa around 102 million years ago — more than 30 million years before the extinction of the dinosaurs.

'Jun Ying Lim, assistant professor at the National University of Singapore, says that “from the perspective of dipterocarps, Southeast Asia must have presented a tremendous ecological opportunity: the heterogeneous, complex and ever-changing geophysical landscape has provided many ways in which speciation may occur.” One example, he explains, is the periodic flooding and draining of the Sunda shelf during the ice ages, which would have led to repeated cycles of isolation driving “formerly contiguous populations to become fragmented, with each fragment diverging from the others to become new species.”'