There is an invisible line that no animal goes through – not even the birds

The animal kingdoms of Asia and Australia are completely different worlds, thanks to an invisible line that runs between the two neighboring continents.

Most of the wildlife never cross this imaginary bordernot even the birds.

And so it has been for tens of millions of years, shaping animal evolution in different ways on each side, tells the.

It all started about 30 million years agowhen the Australian tectonic plate collided with the Eurasian tectonic plate and created an archipelago, redirecting ocean currents and creating new regional climates.

On one side of the map, In Indonesia and Malaysia, monkeys evolvedsteps, elephants, tigers and rhinos; While on the other side, in New Guinea and Australia, they bloom marsupials, monotreed, rodents and catatues. Very few species are abundant on both sides.

This curious Faunistic Division is named after Wallace line – In honor of the naturalist Alfred Russel Wallacewhich first noticed the marked difference in animal life (mainly mammals) while exploring the region in the mid -nineteenth century.

“We can consider established that the Lombok Straitbetween Bali and Lombok, with only 24 kilometers wide, marks the limit and separates abruptly two of the Great Zoos of the Globe“Wrote Wallace.

The naturalist later developed independently a theory of evolution at the same time as Charles Darwin. The line it designed on a map over a century has still been considered a hypothetical evolutionary barrieralthough the debates continue to their exact location and mechanisms.

In general, Wallace’s line separates a platform from the Asian continent of an Australian tectonic plate platform. It is a geological linebut also climate and biological.

Deep oceanic channels As the Lombok Strait separate each platform, which makes it difficult to cross animals. Even when sea levels in the distant past were much lower than today, This abyss would still exist.

Although Wallace’s invisible line is more obvious when comparing mammals in Asia and Australia, It also exists for birds, reptiles and other animals.

Same creatures with wings usually do not travel through the Wallace line, and in the ocean, Some types of fish and microbes They show genetic differences on one side of the border compared to the other, indicating very little mix between populations.

Scientists have not yet found that invisible barriers are preventing these species. Habitat and climate, however, are probably factors that accentuate the evolutionary division.

In 2023, an analysis of More than 20,000 vertebrate species He found that Southeast Asian strains evolved into a relatively tropical ancient environment that allowed them to spread toward New Guinea on moist islands that served as “trampolins”.

Wildlife on the Australian continental shelf, however, evolved into distinctly drier conditions, which dictated a different evolutionary path. This meant that Australian wildlife was at a disadvantage on the nearest tropical islands to Ecuador.

The more researchers study the Wallace line, however, the less clear it becomes where the line should be drawn and how “porous” the barrier can be – At least for some animals that can swim, float or fly, Like bats, beetles, monitors or monkeys.

Wallace’s division It is not an absolute borderBut one more gradient, the scientists say. Even so, the blurred line helps us understand the animal evolution of thousands of species.

But what started as a single line, placed approximately over a century ago, helped the shape a larger and more complicated image of the natural world and its mysteries.