The Wallace Line: Borders Aren’t Just For Humans, This One Divides Animals – News18

Last Updated:February 19, 2025, 10:20 IST

This line named after Alfred Russel Wallace, marks a boundary between Asian and Australian species in Southeast Asia, separating distinct habitats and species

One often hears that borders are only for humans. But what if that is not the case? In fact, borders exist for animals too. This is not a modern phenomenon, but something that occurred long ago. Scientists have named this border the Wallace Line.

Dr Penny van Oosterzee, an ecological researcher at James Cook University, has studied the areas where the Wallace Line falls for many years. She stated that numerous obstacles prevent habitats from merging, even after geographical barriers dissipate.

The Wallace Line, located in Southeast Asia, marks a distinct boundary between Asian and Australian species. This invisible line traverses the waters separating Borneo and Sulawesi, and Bali and Lombok, islands a mere 15 miles apart. Despite its unofficial status, the Wallace Line effectively functions as a biological border for numerous animal species.

The Makassar Strait plays a crucial role in the region’s biodiversity. Its deep ocean trench acted as a barrier during periods of lowered sea levels centuries ago, preventing islands from connecting. This enduring separation resulted in distinct habitats on either side of the strait. Consequently, the animal and plant species differ significantly. Furthermore, the climate and food sources on one side are often unsuitable for species from the other, even hindering birds from crossing over.

The line, named after the scientist Alfred Russel Wallace, commemorates his independent work on the concept of natural selection alongside Darwin. His research reinforced the understanding that species develop based solely on their environment. The Wallace Line has since become a symbol of distinct biogeographical realms separated by geographical divisions. Interestingly, some studies suggest that the location of the Wallace Line has shifted over time.