Scientists: Madagascar’s unique wildlife is facing an imminent wave of mammalian extinction

From the ring-tailed lemur to the aye-aye, a nocturnal primate, more than 20 million years of unique evolutionary history could be wiped from the planet if nothing is done to stop the extinction of Madagascar’s threatened mammals, according to a new study.

It will take 3 million years to restore the diversity of mammal species that have been driven to extinction since humans settled the island 2,500 years ago. But there is a much greater danger in the coming decades: If Madagascar’s threatened mammal species become extinct, the life forms that 23 million years of evolutionary history created will be destroyed.

“Our results indicate that an extinction wave with profound evolutionary impact is imminent in Madagascar unless immediate protection measures are taken,” the researchers wrote in a paper published in the journal Nature Communications. Madagascar is one of the biodiversity hotspots on the planet with 90% of its species found nowhere else on the planet, yet more than half of its mammal species are threatened with extinction.

There’s a lot at stake because the island is relatively pristine and home to wildlife that didn’t evolve anywhere else, after it was separated from Greater India some 88 million years ago. It is the fourth largest island in the world, about the size of Ukraine, and much of its diversity is built on species that came from Africa and then diversified over millions of years.

“It’s about setting the record straight – we’re missing out on unique species traits that will probably never evolve again,” said lead researcher Dr Luis Valente of the Naturalis Center for Biodiversity in Leiden, the Netherlands, and the University of Groningen. “All genres have value in themselves; it’s like destroying a piece of art, so what’s happening is so shocking.” His team collaborated with researchers from the United States and conservation organization Vahatra in Madagascar.

A ring-tailed lemur in a reserve in Toliara Province, Madagascar. Photograph: Alex Konstantinidis/Reuters

The island is particularly famous for its ring-tailed lemurs, members of a unique breed of primate found nowhere else. Other known residents include the fossa, a carnivorous cat-like animal, and the tiger chameleon, as well as a wide variety of unique butterflies, orchids, baobabs and many other species.

Biologists and paleontologists created a dataset that showed all mammal species currently on the island, those that were alive when humans arrived, and those that were only known from fossil records. Of the 249 identified species, 30 are extinct. More than 120 of the 219 species of mammals that live on the island today are threatened with extinction.

Lost species can never return, and so the study looked at how long it would take to restore the same levels of biodiversity through colonization and evolution of new species on the island.

tenrec striped lowland.  Tenrec is a diverse and unique group of mammals found only in Madagascar.
tenrec striped lowland. Tenrec is a diverse and unique group of mammals found only in Madagascar. Photo: Shin Se Lee/PA

“A lot of these species could go extinct in the next 10 or 20 years — they can’t wait much longer,” Valiente said. “You can quickly get to a point where a species is not viable anymore. The main message is that biodiversity is not going to recover quickly. Even places Which we think is really pure and untouched can be pushed to breaking point very quickly.”

The loss of mammals will have major impacts on other species of plants and insects that depend on them. “It’s a chain effect — the loss of these mammals is likely to lead to ecosystem collapse on a larger scale. Altogether, more than 23 million years are likely at stake,” Valiente said.

The main threats are man-made habitat destruction, climate change and hunting. Over the past decade, the number of endangered mammal species in Madagascar has more than doubled, from 56 in 2010 to 128 in 2021. Conservation programs are needed to create livelihoods for local people and stop the conversion of forests to farmland, the paper’s authors said. Reducing the exploitation of resources such as hardwood trees and animals used for bushmeat.

The Madagascar bat belongs to an ancient family of bats found only on the island.
The Madagascar bat belongs to an ancient family of bats found only on the island. Photography: Shin Se Lee

“This fascinating study shows that it will take millions of years for natural processes to rebuild levels of biodiversity already lost, and tens of millions of years if currently threatened species are also lost,” said Yadvinder Malhi, Professor of Ecosystem Science at the University of Oxford, who was not involved in the research. The study in Madagascar, similar analyzes can be done for other islands and continents, and I think they would tell a similar story.

He added, “The impact humanity has already had on Earth’s biodiversity will last for millions of years, but the next few decades are critical to avoiding large-scale extinctions that could have much deeper and longer-lasting consequences.”

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