The iconic symbol of Australia, kangaroo has never been found outside its native land. This has long puzzle scientists, but a new study has shed light on the secrets of the species. Led by biologists at The Australian National University (ANU) and ETH Zurich in Switzerland, researchers have discover that the uneven distribution of Australian and Asian species is due to changing plate tectonics and a dramatic shift in Earth’s climate tens of millions of years ago.
This explanation sheds light on the mystery of Wallace’s Line, an imaginary boundary separating Australia, New Guinea, and parts of Indonesia from continental Southeast Asia.
As per the study, species originating from Asia were more successful at adapting to and settling in Australia due to their ability to tolerate a wide range of climatic conditions.
Dr. Alex Skeels, a biologist at ANU Said :
“If you travel to Borneo, you won’t see any marsupial mammals, but if you go to the neighboring island of Sulawesi, you will. Australia, on the other hand, lacks mammals typical of Asia, such as bears, tigers or rhinos,”.
He explain that this uneven distribution of animal species is partly due to changes in ancient plate tectonics dating back 45 million years.
These changes led to a “continental collision” that alter the geographic composition of Earth.
Dr. Alex Skeels Said :
“About 35 million years ago, Australia was located much further south and was connected to Antarctica,”.
“At some point in Earth’s timeline, Australia broke away from Antarctica and over millions of years drifted north, causing it to crash into Asia. That collision gave birth to the volcanic islands that we now know as Indonesia.”
These Indonesian islands serve as “stepping stones” for animals and plants originating from Asia to reach New Guinea and northern Australia.
So, the Australian species, which had evolve in a cooler and increasingly drier climate over time, were less successful in gaining a foothold on the tropical islands compare to the creatures migrating from Asia.
The researchers analyse a dataset of about 20,000 birds, mammals, reptiles, and amphibians to determine which species hopped between Indonesia and Australia, and which ones were able to successfully adapt to their new home.
Dr. Alex Skeels Said :
“Our findings could also inform predictions for animal migration in the future and help us predict which species may be better versed at adapting to new environments, as changes to Earth’s climate continue to impact global biodiversity patterns,”.
This study not only provides an explanation for the absence of kangaroos outside Australia but also offers valuable insights into the effects of climate change on global biodiversity over millions of years.
