Just 0.7% of the world’s land surface is home to one-third of the world’s most threatened and unique four-legged animals, a recent study has found.
In the vast evolutionary tree of life, some animals, like rats, have many closely related species that are at no immediate risk of extinction. But others, like the red panda (Ailurus fulgens), have no close relatives and are the only species in their family, Ailuridae. You would have to travel back 24 million years on the tree of life to find the red panda’s nearest common ancestor with another living species, a group of animals that includes weasels and racoons. Red pandas are listed as endangered on the IUCN Red List, so if they go extinct, an entire branch on the tree of life would be wiped out.
Researchers set out to find the most taxonomically unique and endangered species living in areas where human pressure may force them into extinction, like the red panda. They wanted to identify so-called EDGE Zones, or places with evolutionarily distinct (ED) species that are globally endangered (GE).
The researchers focused on tetrapods — vertebrates with four legs. They investigated more than 33,000 species worldwide and identified 25 priority tetrapod EDGE Zones across 33 countries. Together, these EDGE Zones account for just 0.72% of the world’s land surface, but they harbor around one-third of the world’s EDGE tetrapod species. Roughly half of those species are endemic, found nowhere else on Earth.
Many EDGE Zones for tetrapods are in the tropics and on islands: Costa Rica, Peninsular Malaysian, Cameroon and Hispaniola top the list. But the most, 10% or roughly 3,000 EDGE species, are found on the island of Madagascar, home to a wide variety of ecosystems including rainforests, deserts, coasts and mountains more than 2,800 meters (9,000 feet) high.
“It’s a whole world in an island,” Sebastian Pipins, the study’s lead author and a Ph.D. candidate with the Imperial College London, U.K., told Mongabay by phone. “It’s also an island that’s been separated for tens of millions of years from any other area. And so, the diversity there has been able to evolve in isolation, which has led to all of these remarkably unique forms. And then when you bring in the human element and the fact that now a lot of these species are threatened, that means they tick both the boxes to qualify as an edge species, being both unique and imperiled.”
As countries work toward the biodiversity conservation goal of protecting 30% of the world’s land and ocean by 2030, Pipins said his research shows that concentrating efforts on a small portion of the world can have a huge impact toward saving our shared evolutionary heritage.
“Not all species extinctions equate to the same thing. Some result in a larger loss of diversity, and that’s something that we need to consider and account for,” he said.
Banner image: Flickr via Pexels (Public domain).
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