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

It would already take 3 million years to regain the diversity of mammal species that have been on the verge of extinction since man settled on the island 2,500 years ago. But much more is at risk in the coming decades: if Madagascar’s threatened mammal species disappear, the life forms created by 23 million years of evolutionary history will be destroyed.

“Our results suggest that a wave of extinction with profound evolutionary impact is imminent in Madagascar unless immediate conservation action is taken,” the researchers wrote in a paper published in Nature Communications. Madagascar is one of the planet’s biodiversity hotspots with 90% of its species found nowhere else on the planet, but more than half of its mammal species are threatened with extinction.

So much is at stake because the island is relatively pristine and home to wildlife that evolved nowhere else, having split off from greater India around 88 million years ago. It’s the fourth largest island in the world, roughly the size of Ukraine, and much of its diversity has been built on species originating in Africa and then diversifying over millions of years.

“It’s about putting things into perspective – we are losing unique species traits that will probably never evolve again,” said lead researcher Dr Luis Valente of the Naturalis Biodiversity Center in Leiden, the Netherlands. , and the University of Groningen. “Each species is valuable in itself; it’s like destroying a work of art, so what’s happening is very shocking. His team collaborated with American researchers and the conservation organization Association Vahatra in Madagascar.

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

The island is particularly known for its ring-tailed lemurs, members of a unique lineage of primates found nowhere else. Other well-known inhabitants include the pit, a cat-like carnivorous animal, and the panther chameleon, as well as a huge array of unique butterflies, orchids, baobabs and many other species.

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

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

A lowland striated tenrec.  Tenrec is a diverse and unique group of mammals found only in Madagascar.
A lowland striated tenrec. Tenrec is a diverse and unique group of mammals found only in Madagascar. Photograph: Dog C Lee/PA

Valente said: “A lot of these species could go extinct in the next 10 or 20 years – they can’t wait much longer. You can quickly reach a point where a species is no longer viable. The main message is that biodiversity is not going to recover quickly. Even places that we think are pristine and truly untouched can be pushed to the point of collapse quite quickly.

The loss of mammals would have significant impacts on other plant and insect species that depend on them. Valente said: “It’s a cascading effect – the loss of these mammals would likely cause the ecosystem to collapse more broadly. In total, there will likely be over 23 million years in play.”

The main threats are habitat destruction by humans, 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 people to prevent the conversion of forests to agricultural land and to limit the exploitation of resources such as hardwood trees and animals used for bushmeat, the paper’s authors said.

The Madagascar sucker-footed bat belongs to an ancient family of bats found only on the island.
The Madagascar sucker-footed bat belongs to an ancient family of bats found only on the island. Photography: Dog C Lee

Yadvinder Malhi, professor of ecosystem science at the University of Oxford, who was not involved in the research, said: “This fascinating study shows that it would take millions of years for natural processes to replenish the levels of biodiversity already lost, and tens of millions of years if currently threatened species also disappear. While this study focused on Madagascar, similar analyzes could be done for other islands and continents, and I think they would tell a similar story.

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

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