Picture yourself relaxing on a sandy beach, taking in the stunning sight of Lombok just northeast of Bali. But did you know that as you admire this view, you’re actually crossing a hidden boundary called the Wallace Line?
Named after the British naturalist Alfred Russel Wallace, this line marks a split between the plants and animals of nearby islands, shaped by ancient geological shifts and evolutionary processes. But does it matter in today’s world?
Researchers from the Department of Ecology and Evolution at UNIL have dived into this question, focusing on ants. Led by Lucie Aulus-Giacosa, they’ve looked into how human activities like global trade and tourism are changing the homes of ant species around the world.
“A lot of past studies focused on snails, but our work on ants, which make up a big part of Earth’s animal life, has revealed some surprising discoveries,” says Aulus-Giacosa. “We’ve found that even a small influx of non-native ant species can really shake up ecosystems, affecting not just the ants we’ve studied but the whole ant community.”
In simpler terms, tropical areas are becoming more alike. Whether you’re in Australia, Africa, or South America, you’re more likely to come across similar ant species. Cleo Bertelsmeier, the project’s leader, thinks this would surely surprise Wallace!
This blending of species is because of the rich variety of life found in the tropics. These regions not only create many different species but also help them adapt to similar climates elsewhere. “It’s worrying to realize that in just 200 years, we’ve disrupted millions of years of ant evolution,” notes Bertelsmeier, showing how deeply humans are affecting Earth’s biodiversity.
The research shows a troubling trend: more than half of the world’s ant communities are becoming more similar, especially in tropical areas and on islands. These places, with their unique ecosystems, are especially vulnerable to human impact, raising concerns about the future of distinct species.
Looking forward, the researchers want to focus on islands, where tourism and trade often introduce invasive species that harm local wildlife. “We’re trying to understand why islands are seeing bigger changes,” explains Aulus-Giacosa, stressing the urgent need to protect these delicate ecosystems.