Biodiversity: Extinctions may threaten Madagascar’s biodiversity for millions of years

Madagascar’s biodiversity could take millions of years to recover to levels before the arrival of humans if threatened animal species become extinct, according to a Nature Communications paper. The findings suggest that immediate conservation efforts are needed to avoid long-lasting biodiversity losses.

Madagascar is home to a unique set of animal species, including the ring-tailed lemur, the fossa and the world’s smallest chameleon. Many of these species are threatened with extinction owing to human influences such as deforestation, hunting and climate change. Evolution and the arrival of new species from other regions may eventually compensate for these extinctions, but this would take a very long time.

Nathan Michielsen and colleagues attempted to quantify the extent to which humans have disrupted the fauna of Madagascar and forecast future outcomes. They assembled a comprehensive dataset of 249 living and recently extinct mammals, including species that disappeared shortly after humans first arrived on the island, such as several species of giant lemurs and dwarf hippos. By combining these data with species’ evolutionary history and statistical models of their geographical distribution over time, the authors estimated that it would take 3 million years for Madagascar to recover the species that have been lost since human arrival if current threats were not mitigated. Additionally, it would take more than 20 million years if currently threatened species were lost as well. They suggest that even bat species, which can colonise islands more easily than non-flying mammals, may need about 3 million years to recover. The authors also found that the number of Madagascar’s mammal species threatened with extinction has increased dramatically in the past decade, from 56 in 2010 to 128 in 2021.

The authors warn that, without timely conservation actions, the biodiversity of Madagascar could be impacted for millions of years. They suggest that conservation programs should include socio-economic improvements for local human populations, reducing forest loss in the remaining natural habitats, and limiting artisanal and commercial resource exploitation, such as of hardwoods and animals for the bushmeat trade.