More than 160 years after its original founding, scientists have finally solved the evolutionary mystery surrounding the Wallace Line, an imagined and real biogeographic boundary. This boundary, named after renowned British naturalist Alfred Russell Wallace, was observed during his exploration of the Malay Archipelago, which incorporates greater than 25,000 islands positioned between Southeast Asia and Australia.
Wallace noticed a big change in species composition beyond a certain point, which led to the delineation of the Wallace Line. The creatures on the Asian side of the border were exclusively from Asia, while on the Australian side they represented a mix of Asian and Australian origins. This asymmetrical distribution of species has perplexed ecologists for over a century.
Recent research has make clear this mystery, suggesting that the driving force behind the uneven distribution of species was extreme climate change attributable to tectonic activity around 35 million years ago. During this era, Australia broke away from Antarctica and collided with Asia, giving rise to the Malay Archipelago.
Using computer simulations, scientists examined the results of those climate changes on greater than 20,000 species on either side of the Wallace Line. They determined that Asian species were higher adapted to the climatic conditions then prevailing within the archipelago. The separation of Australia and Antarctica led to the formation of the Antarctic Circumpolar Current (ACC), which cooled the climate significantly and created a contrast between the nice and cozy and wet conditions in Southeast Asia and the islands and the cold and dry climate in Australia.
As a result, Asian species found the Malay Archipelago favorable to their survival and used it as a springboard to migrate towards Australia. In turn, Australian species, adapted to a colder and drier climate, struggled to realize a foothold on tropical islands. This discrepancy in adaptability explains the observed pattern of species distribution along the Wallace Line.
The results of this study have implications not just for understanding past evolutionary events, but in addition have implications for predicting the results of up to date climate change on living species. Using a pc model, researchers wish to predict how current climate change may affect species distributions and biodiversity patterns all over the world.
