Madagascar launches an SOS: from the famous fossa lemurs, resembling their predator and a small puma, to the strange sucker bat, 120 species of mammals are threatened with extinction, more than 50% of the 219 in the world island symbol of biodiversity. They took 23 million years of evolution to thrive and would take as many to rebuild if they disappeared: a much longer time span than previously thought. It’s the estimate of the study published in the journal Nature Communications and led by the Center for Natural Biodiversity of Leiden in the Netherlands that sounds the alarm: according to the study’s authors, there are only 5 years left to save Madagascar from the point of no return.
The bat, Myzopoda aurita, belongs to an ancient family of bats unique to Madagascar (Source: Chien C. Lee)
“It is absolutely clear that there are unique mammals found only in Madagascar, some of which are already extinct or on the verge of extinction,” says Steve Goodman of the Field Museum of Natural History in Chicago, co-author of the study led by Nathan Michielsen: “Unless immediate action is taken, Madagascar will lose 23 million years of evolutionary history, meaning many unique species on Earth will no longer exist”.
Madagascar is the fifth largest island in the world, but if we think about the richness of ecosystems and biodiversity, it’s more like a mini-continent: its remoteness has actually allowed plants and animals to evolve in unique ways, imagine it 90% of the species are found nowhere else. A biodiversity that has been under constant threat since humans settled permanently on the island some 2,500 years ago: since then, many extinctions have already occurred, including those of giant lemurs, elephant birds and pygmy hippos.
Microcebus rufus, one of Madagascar’s critically endangered lemur species (Source: Chien C. Lee)
To quantify the risk to life on the island, the researchers compiled an unprecedented set of data describing the evolutionary relationships among all mammalian species present on Madagascar at the time of colonization, a total of 249. Using computer simulations, the authors were able to calculated how long it took for this biodiversity to evolve, and how long it would take for evolution to “replace” all mammals in the event of an extinction.
The results show that 120 of the 219 species currently alive are on the verge of extinction. It will take 3 million years to rebuild the diversity of animals that are already extinct, but much more, 23 million years, will be needed if the present ones also become extinct. A time span that surprised the researchers: “It is much more than what previous studies have calculated for other islands – comments Luis Valente, one of the authors of the study – like New Zealand or the Caribbean.” This doesn’t mean that if lemurs disappeared, they could return to Earth in 23 million years: what the study highlights is the amount of time it would take for evolution to return to a similar level of complexity, even if the species would be entirely new.
The hedgehog Hemicentetes semispinosus, which belongs to a globally unique group of mammals, is found only in Madagascar (Source: Chien C. Lee)