More than 20 million years of unique evolutionary history from ring-tailed lemurs to the aye-aye, a nocturnal primate, could be wiped from the planet if nothing is done to halt the extinction of Madagascar’s endangered mammals, according to a new study.
It would already take 3 million years to restore the diversity of mammal species that have been threatened with extinction since the island was settled 2,500 years ago. But there is much more at stake in the coming decades: if endangered mammal species become extinct in Madagascar, life forms that have evolved over 23 million years of evolutionary history will be destroyed.
“Our findings suggest that unless conservation action is taken immediately, Madagascar may face an extinction wave with profound evolutionary implications,” researchers wrote in a paper published in Nature Communications. Madagascar is one of the planet’s biodiversity hotspots, as 90% of its species are found nowhere else on earth, but more than half of its mammalian species are threatened with extinction.
The stakes are so high because the island is relatively untouched and is home to wildlife that has not evolved anywhere else after splitting from Greater India some 88 million years ago. It’s the fourth largest island in the world, about the size of Ukraine, and much of its diversity was built on species that originated in Africa and then diversified over millions of years.
“It’s about putting things in perspective – we’re losing unique species traits that will likely never evolve again,” said lead researcher Dr. Luis Valente from the Naturalis Biodiversity Center in Leiden, the Netherlands, and the University of Groningen. “Each species is valuable in its own right; It’s like destroying a work of art, so what happens is very shocking.” His team worked with researchers from the US and the conservation organization Association Vahatra in Madagascar.
A ring-tailed lemur in a reserve in Toliara province, Madagascar. Photo: Alkis Konstantinidis/PortalThe island is particularly well known for its ring-tailed lemurs, members of a unique lineage of primates found nowhere else. Other well-known residents include the fossa, a carnivorous feline, and the panther chameleon, as well as a wide range of unique butterflies, orchids, baobabs and many other species.
Biologists and paleontologists have created a dataset showing all mammalian species currently found on the island, those inhabited when humans arrived, and those known only from the fossil record. Of the 249 species identified, 30 are extinct. More than 120 of the 219 species of mammals living on the island today are threatened with extinction.
Lost species can never return, and so the study examined how long it would take to restore the same level of biodiversity from new species colonizing and evolving on the island.
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A striped tenrec in the lowlands. Tenrec are a diverse and unique group of mammals found only in Madagascar. Photo: Chien C. Lee/PA
Valente said: “Many of these species could become extinct in the next 10 or 20 years – they can’t wait much longer. It can quickly come to a point where a species is no longer viable. The main message is that biodiversity will not recover quickly. Even the places that we think are pristine and truly untouched can be brought down pretty quickly.”
The loss of mammals would have a significant impact 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 a broader ecosystem collapse. Altogether there are probably more than 23 million years at stake.”
The main threats are human-caused habitat destruction, climate change and hunting. In the last decade, the number of mammal species threatened with extinction in Madagascar has more than doubled, from 56 in 2010 to 128 in 2021. Conservation programs are needed to provide livelihoods for local people to prevent forests Converted to farmland Limit exploitation of resources such as hardwood trees and animals used for bushmeat, the paper’s authors said.
The Madagascar sucker bat belongs to an ancient family of bats found only on the island. Photo: Chien C LeeYadvinder Malhi, Professor of Ecosystem Sciences at the University of Oxford, who was not involved in the research, said: “This fascinating study shows that it would take natural processes millions of years for natural processes to rebuild already lost biodiversity, and tens of years Millions of years, even if currently threatened species are lost. While this study was about Madagascar, similar analyzes could be done for other islands and continents, and I think they would tell a similar story.
He added: “The impacts humanity has already had on Earth’s biodiversity will last for millions of years, but the next few decades are critical to avoiding a large-scale extinction that could have much deeper and longer-lasting consequences.”