In many ways, Madagascar is a biologist’s paradise. It is the fifth largest island in the world, the size of France, separated by 150 million years from Africa and 80 million from the Indian subcontinent. About 90% of life on Madagascar is found nowhere else on Earth.
After human colonization 2,500 years ago, the island suffered the extinction of giant lemurs, elephant birds and dwarf hippos, among many other animals. And while its fauna remains relatively intact, it is also in dire straits.
About 90% of life on Madagascar is found nowhere else on Earth
A new study published in the journal Nature Communications calculates that if species currently classified as endangered become extinct, it would take 23 million years of evolution to restore the island’s biodiversity, much longer than previously estimated for any other island.
In the case of terrestrial mammals that have already been extinguished by human action, it would take about three million years.
Myzopoda aurita belongs to a family of bats unique to Madagascar. / Chien C. Lee
An incipient socioecological catastrophe
Speaking to SINC, Luis Valente, a scientist at the Naturalis Biodiversity Center and the University of Groningen (Netherlands) and co-author of the study, warned that the extinction of endemic species in Madagascar could cause “the collapse of the island’s ecosystems, as many species of plants and animals depend on them”. But the problem is not just biological, as this environmental disaster “would affect the island’s food security and water supply, producing famines and massive migrations of human populations.”
“If immediate action is not taken, entire lineages unique to the face of the Earth will never exist again,” said Steve Goodman, a biologist at the Field Museum in Chicago and another co-author of the paper.
Madagascar’s biological crisis has nothing to do with biology, but with socioeconomics
Steve Goodman
Valente finds it difficult to predict how long it will be before the island’s endangered mammals disappear completely. However, he notes that “some lemur species with very small populations could become extinct in the next 10 to 20 years.”
As a first measure, it proposes to stop the destruction of habitats by increasing the size and quality of the network of protected areas. “These areas are not effective if the human populations that live near them do not have a good standard of living”, he says.
That urgent conservation work is hampered by inequality and political corruption that keep land-use decisions out of reach for most Malagasy people, Goodman denounces. “The biological crisis in Madagascar has nothing to do with biology, but with socioeconomics”, he emphasizes.
The Hemicentetes semispinosus is a species of tenrec, an animal endemic to Madgascar. / Chien C. Lee
The team, made up of biologists and paleontologists from Europe, Madagascar and the United States, created an unprecedented new dataset that describes the evolutionary relationships of all mammalian species present on Madagascar since humans colonized the island.
In total, the researchers found 249 species, 30 already extinct and 219 still surviving. More than half of the fauna, 120 animals, are classified as endangered in the red list of the International Union for Conservation of Nature.
Scientists don’t want to say that exactly the same species would recover over time, but the same degree of evolutionary complexity
Armed with this dataset, scientists constructed genetic family trees to establish the relationship between all these species and the time it took them to evolve from their various common ancestors. They also extrapolated evolutionary time to estimate how long it would take to “replace” all endangered mammals if they went extinct.
This does not mean that exactly the same species would recover over time, but rather the same degree of evolutionary complexity. “It would simply be impossible to recover lost animals,” laments Goodman.
A mouse lemur (Microcebus) / Vahatra Association
Other similar studies on islands in New Zealand or the Caribbean suggest much shorter time periods, says Valente. “These findings highlight the potential benefits of nature conservation in Madagascar from a new evolutionary perspective,” he adds.
These findings highlight the potential benefits of conservation in Madagascar from a new evolutionary perspective.
luis valiant
According to Goodman, Madagascar is at a critical point in protecting its biodiversity. “There’s still room to fix things, but basically we have about five years to really make progress in conserving Madagascar’s forests and the organisms they host,” he says.
Despite the precarious situation, the scientist maintains a persevering attitude: “We have an obligation to advance this cause as much as we can and try to make the world understand that it is now or never”, he concludes.
Reference
Valente, L. et al., “The macroevolutionary impact of recent and impending mammalian extinctions in Madagascar”. Nature Communications (2023).