It could take 23 million years to replace Madagascar’s endangered mammals

By Mark Waghorn via SWNS

It would take 23 million years for evolution to replace Madagascar's endangered mammals, according to new research.

Immediate conservation efforts are needed to avoid long-lasting biodiversity losses, say scientists.

The haven in the Indian Ocean is home to a unique set of animals, including the ring-tailed lemur, the fossa and the world's smallest chameleon.

It is a real-life experiment on how isolation on an island can spark evolution.

Madagascar is one of the last land masses to be colonized by humans. More than 90 percent of its reptiles, plant life and mammals are found nowhere else on Earth.

But they are in major trouble - turning the biologist's dream into a nightmare.

Many species are threatened with extinction owing to deforestation, hunting and climate change.

Co-author Dr. Steve Goodman, of Chicago's Field Museum, said: "It is abundantly clear there are whole lineages of unique mammals that only occur on Madagascar that have either gone extinct or are on the verge of extinction.

"If immediate action isn't taken, Madagascar is going to lose 23 million years of evolutionary history of mammals, which means whole lineages unique to the face of the Earth will never exist again."

The study quantifies for the first time the extent to which humans have disrupted the fauna over the past two centuries - and forecasts future outcomes.

An international team assembled a comprehensive dataset of 249 living and recently extinct mammals.

Some disappeared shortly after humans first settled on the island 2,500 years ago.

Huge lemurs as big as a gorilla, ten-foot-tall elephant birds, puma-like predators called giant fossas and dwarf hippos once roamed the island.

Then, after millions of years of evolution, they disappeared - in just a couple of centuries.

Combining evolutionary history and statistical models of geographical distribution over time showed it would take three million years for Madagascar to recover the species that have been lost.

Alarmingly, it would take more than 20 million years if currently threatened species went as well.

Even bats, which can colonize islands more easily than non-flying mammals, may need about three million years to recover.

Dr. Goodman and colleagues also found the number of mammal species threatened with extinction has increased dramatically in the past decade - from 56 in 2010 to 128 in 2021.

Madagascar is the world's fifth-largest island - about the size of France.

But Dr. Goodman said: "In terms of all the different ecosystems present on Madagascar, it is less like an island and more like a mini-continent"

Madagascar split from the mainlands of Africa and India 150 million and 80 million years ago, respectively.

Plants and animals have since gone down their own evolutionary paths, cut off from the rest of the world.

A smaller gene pool and wealth of habitats - from mountainous rainforests to lowland deserts - allowed mammals to split into different species far more quickly than their continental relatives.

But incredible biodiversity comes at a cost. Evolution happens faster on islands - but so does extinction.

Smaller populations are specially adapted to smaller, unique environments and are more vulnerable to being wiped out.

More than half of the mammals on Madagascar are included on the IUCN (International Union for Conservation of Nature) Red List of Threatened Species, aka the IUCN Red List.

The researchers built a dataset of every known mammal species to co-exist with humans on Madagascar for the last 2,500 years.

They identified 219 known today, plus 30 more that have gone extinct over the past two millennia.

Malagasy mammals that interacted with humans enabled genetic family trees to be drawn.

They established how all these species are related to each other and how long it took them to evolve from their various common ancestors.

The scientists extrapolated how long this amount of biodiversity took - and how long it would take to 'replace'.

If we let lemurs, tenrecs, fossas and other unique mammals go extinct, evolution won't recreate them if we just wait around 23 million years.

Dr. Goodman said: "It would be simply impossible to recover them."

Instead, the model means this would be the time to achieve a similar level of evolutionary complexity, whatever those new species might look like.

Corresponding author Dr. Luis Valente, of the University of Groningen, The Netherlands, described the discovery as surprising.

He said: "It is much longer than what previous studies have found on other islands, such as New Zealand or the Caribbean.

"It was already known Madagascar was a hotspot of biodiversity, but this new research puts into context just how valuable this diversity is.

"These findings underline the potential gains of the conservation of nature on Madagascar from a novel evolutionary perspective."

Madagascar, now home to 25 million people, is at a tipping point for protecting its biodiversity.

Dr. Goodman said: "There is still a chance to fix things, but basically, we have about five years to really advance the conservation of Madagascar's forests and the organisms that those forests hold."

Urgent conservation work is made difficult by inequality and political corruption that keeps land-use decisions out of the hands of most Malagasy people.

Dr. Goodman said: "Madagascar's biological crisis has nothing to do with biology. It has to do with socio-economics."

But while the situation is dire, "we can't throw in the towel."

He added: "We are obliged to advance this cause as much as we can and try to make the world understand it is now or never." The study is in Nature Communications.

What is remarkable about the crash in Madagascar is it occurred relatively recently. It has implications for today.

Many remaining giants, such as elephants and rhinos, are threatened or endangered. The study is in Nature Communications.