ZME Science
  • News
  • Environment
  • Health
  • Future
  • Space
  • Features
    • Natural Sciences
    • Physics
      • Matter and Energy
      • Quantum Mechanics
      • Thermodynamics
    • Chemistry
      • Periodic Table
      • Applied Chemistry
      • Materials
      • Physical Chemistry
    • Biology
      • Anatomy
      • Biochemistry
      • Ecology
      • Genetics
      • Microbiology
      • Plants and Fungi
    • Geology and Paleontology
      • Planet Earth
      • Earth Dynamics
      • Rocks and Minerals
      • Volcanoes
      • Dinosaurs
      • Fossils
    • Animals
      • Mammals
      • Birds
      • Fish
      • Amphibians
      • Reptiles
      • Invertebrates
      • Pets
      • Conservation
      • Animal facts
    • Climate and Weather
      • Climate change
      • Weather and atmosphere
    • Health
      • Drugs
      • Diseases and Conditions
      • Human Body
      • Mind and Brain
      • Food and Nutrition
      • Wellness
    • History and Humanities
      • Anthropology
      • Archaeology
      • History
      • Economics
      • People
      • Sociology
    • Space & Astronomy
      • The Solar System
      • Sun
      • The Moon
      • Planets
      • Asteroids, meteors & comets
      • Astronomy
      • Astrophysics
      • Cosmology
      • Exoplanets & Alien Life
      • Spaceflight and Exploration
    • Technology
      • Computer Science & IT
      • Engineering
      • Inventions
      • Sustainability
      • Renewable Energy
      • Green Living
    • Culture
      • Culture & Society
      • Bizarre Stories
      • Lifestyle
      • Art and Music
      • Gaming
      • Books
      • Movies and Shows
    • Resources
      • How To
      • Science Careers
      • Metascience
      • Fringe Science
      • Science Experiments
      • School and Study
  • Reviews
  • More
    • Agriculture
    • Anthropology
    • Biology
    • Chemistry
    • Electronics
    • Geology
    • History
    • Mathematics
    • Nanotechnology
    • Economics
    • Paleontology
    • Physics
    • Psychology
    • Robotics
  • About Us
    • About
    • The Team
    • Advertise
    • Contribute
    • Privacy Policy
    • Contact
No Result
View All Result
ZME Science

No Result
View All Result
ZME Science

Home → Science → News

There’s an invisible barrier that separates Asian and Australian species. Scientists now know why

Ever wondered why you won't find kangaroos outside Australia? It all started with massive climate change millions of years ago.

Tibi Puiu by Tibi Puiu
July 24, 2023
in Animals, Biology, News
Edited and reviewed by Zoe Gordon

Scientists have finally solved the puzzle of the mysterious Wallace Line that runs through Indonesia, providing an explanation for the uneven distribution of animal species on either side of this boundary. This invisible but impactful line, first mapped out by British naturalist Alfred Russel Wallace more than 160 years ago, has puzzled researchers for centuries. But now, a new study sheds light on its origin and the factors that shaped it.

The Wallace Line

You've likely heard of famed naturalist Charles Darwin, but not a lot of people know that Alfred Russel Wallace, also a British naturalist, independently proposed a theory of evolution due to natural selection around the same time as Darwin. He is best known, however, for something you might find quite intriguing: the Wallace Line.

In the 19th century, while on an expedition, Wallace noted a surprising contrast in animal species on either side of an invisible boundary running between the Indonesian islands of Borneo and Sulawesi. To the west, the islands— including Borneo, Java, and Sumatra— are home to animals commonly found in Southeast Asia. However, when you move east past the line to islands like Sulawesi, New Guinea, and the Moluccas, the animals are more akin to species found in Australia.

Wallace Line
The Wallace Line. Credit: Wikimedia Commons.

The Wallace Line delineates two distinct zones of animal and plant life. But the curious thing about this line is that it exists despite the geographical proximity of the islands. One might expect a gradual transition of species between areas so close, but that's not the case here.

This clear division of wildlife has puzzled scientists for over a century. Now, a new study may have finally explained the conundrum: extreme climate change triggered by tectonic activity around 35 million years ago played a crucial role in creating the Wallace Line.

Around that time, Australia drifted away from Antarctica and collided with Asia, causing significant changes in geography and also Earth's climate. The continental collision birthed the volcanic islands of Indonesia while also opening up a deep ocean surrounding Antarctica. In turn, this led to the formation of the Antarctic Circumpolar Current, which dramatically cooled the climate.

Stepping stones across Indonesia

The findings were made by biologists at the Australian National University (ANU) and ETH Zurich in Switzerland, who ran a computer model that predicts how this ancient tectonic event affected the range and diversification of species. This model revealed that the changing climate affected species differently on both sides of the Wallace Line.

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," Dr Alex Skeels, from ANU, said. 

Although the global cooling caused by the merger of Australia and Asia unleashed a mass extinction event, the climate on the newly formed Indonesian islands was relatively welcoming for life: it was warm, wet, and tropical, much like today.

"So Asian fauna were already well-adapted and comfortable with these conditions, so that helped them settle in Australia," Skeels said.

"This was not the case for the Australian species. They had evolved in a cooler and increasingly drier climate over time and were therefore less successful in gaining a foothold on the tropical islands compared to the creatures migrating from Asia." 

kangaroo chilling
Credit: Wikimedia Commons.

The researchers hope that their computer model can help forecast how modern-day climate change will impact living species. By understanding how species adapted to historical climate changes, scientists can better predict which species may be more adept at adapting to new environments in the future.

The Wallace Line serves as a demonstration of how geographical and geological factors can influence biodiversity. But it is not the only example. Closer to the Wallace Line, you'll find two other lines named after the scientists who discovered them: Weber's Line and Lydekker's Line.

Weber's line runs east of the Wallace Line and shows a gradual transition from Asian to Australian species. Further east is Lydekker's Line, which borders the edge of the Australian continent. Beyond this point, the species are predominantly Asian.

The Aïr and Ténéré Line is another fascinating biogeographical boundary. It runs through the Sahara Desert in Niger, separating the Western Saharan flora from the Eastern Saharan flora. Despite the harsh conditions, the regions on either side of this line boast different plant species adapted to their specific environments.

As the climate shifts at an alarming pace, it has perhaps never been more important to study these lines. Although their boundaries may be invisible, their impact is very much real.

The findings appeared in the journal Science.

Tags: wallacewallace line

ADVERTISEMENT
  • About
  • Advertise
  • Editorial Policy
  • Privacy Policy and Terms of Use
  • How we review products
  • Contact

© 2007-2023 ZME Science - Not exactly rocket science. All Rights Reserved.

No Result
View All Result
  • News
  • Environment
  • Health
  • Future
  • Space
  • Features
    • Natural Sciences
    • Physics
      • Matter and Energy
      • Quantum Mechanics
      • Thermodynamics
    • Chemistry
      • Periodic Table
      • Applied Chemistry
      • Materials
      • Physical Chemistry
    • Biology
      • Anatomy
      • Biochemistry
      • Ecology
      • Genetics
      • Microbiology
      • Plants and Fungi
    • Geology and Paleontology
      • Planet Earth
      • Earth Dynamics
      • Rocks and Minerals
      • Volcanoes
      • Dinosaurs
      • Fossils
    • Animals
      • Mammals
      • Birds
      • Fish
      • Amphibians
      • Reptiles
      • Invertebrates
      • Pets
      • Conservation
      • Animal facts
    • Climate and Weather
      • Climate change
      • Weather and atmosphere
    • Health
      • Drugs
      • Diseases and Conditions
      • Human Body
      • Mind and Brain
      • Food and Nutrition
      • Wellness
    • History and Humanities
      • Anthropology
      • Archaeology
      • History
      • Economics
      • People
      • Sociology
    • Space & Astronomy
      • The Solar System
      • Sun
      • The Moon
      • Planets
      • Asteroids, meteors & comets
      • Astronomy
      • Astrophysics
      • Cosmology
      • Exoplanets & Alien Life
      • Spaceflight and Exploration
    • Technology
      • Computer Science & IT
      • Engineering
      • Inventions
      • Sustainability
      • Renewable Energy
      • Green Living
    • Culture
      • Culture & Society
      • Bizarre Stories
      • Lifestyle
      • Art and Music
      • Gaming
      • Books
      • Movies and Shows
    • Resources
      • How To
      • Science Careers
      • Metascience
      • Fringe Science
      • Science Experiments
      • School and Study
  • Reviews
  • More
    • Agriculture
    • Anthropology
    • Biology
    • Chemistry
    • Electronics
    • Geology
    • History
    • Mathematics
    • Nanotechnology
    • Economics
    • Paleontology
    • Physics
    • Psychology
    • Robotics
  • About Us
    • About
    • The Team
    • Advertise
    • Contribute
    • Privacy Policy
    • Contact

© 2007-2023 ZME Science - Not exactly rocket science. All Rights Reserved.

Don't you want to get smarter every day?

YES, sign me up!

Over 35,000 subscribers can't be wrong. Don't worry, we never spam. By signing up you agree to our privacy policy.

✕
ZME Science News

FREE
VIEW