EbeneNews – UA – Study investigates factors responsible for Madagascar’s megafauna extinction

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Over the past thousand years, there has been a complete destruction of the endemic megafauna of Madagascar and the Mascarene Islands An international research team has analyzed the likely factors of this extinction by developing a record of 8,000 years of the island’s previous climate

The results of the study revealed that although the ecosystem was resistant to previous climatic stresses, it collapsed with an increase in human activities

Christoph Spötl from the Quaternary Research Group in Innsbruck was one of the members of the international research team The results have now been published in the journal Science Advances

Almost all of the Malagasy megafauna – which includes the famous Dodo bird, giant tortoises, the elephant which was 3m tall and weighed around half a ton and lemurs the size of a gorilla – disappeared between 1500 and 500 years ago from

Did humans hunt these animals to extinction? Or have they disappeared because of climate change? There are different hypotheses, but the real reason for the megafauna collapse remains a mystery and is the subject of intense debate

The Mascarene Islands located to the east of Madagascar are of unique interest as they are the last islands on the planet to be colonized by humans Interestingly, the megafauna of the islands collapsed in just 200 years later human installation

In a study published recently in the journal Science Advances, an international research team found that this may be a « double whammy » related to increased human activity as well as a particularly acute period of aridity throughout the region, which could have led to the elimination of megafauna

The team rejects climate change as the sole reason and instead proposes that the effect of human colonization was a key contributor to the megafauna collapse Hanying Li, postdoctoral researcher at Xi’an Jiaotong University in China and lead author of this study, has compiled an elaborate history of regional climate change

The main source of the new paleoclimatic record comes from the small Mascarene island of Rodrigues, in the southwest of the Indian Ocean, about 1,600 km east of Madagascar

An island so isolated and so small that you won’t find it on most school atlases « 

Li and his collaborators developed their climate records by studying the trace elements as well as the oxygen and carbon isotopes of each incremental growth layer of stalagmites, which was collected from one of the many caves present on this island

Variations in geochemical signatures provided the information necessary to reconstruct the rainfall regimes of the region over the past 8,000 years. To analyze the stalagmites, we used the stable isotope method in our laboratory in Innsbruck « 

Regardless of the distance between the two islands, Rodrigues and Madagascar, summer rainfall is affected by the same global tropical rain belt that fluctuates north and south with the seasons

« And when this belt weakens and stays further north of Rodrigues, droughts can hit the entire region from Madagascar to Rodrigues, » explained Hai Cheng, co-lead author of the study

“Li de Rodrigues’ work demonstrates that the region’s hydroclimate has experienced a series of drying trends over the past 8 millennia, which were frequently punctuated by ‘mega-lice’ that lasted for many years. decades, ”noted Hubert Vonhof, who is a study co-author and scientist at the Max Planck Institute for Chemistry in Mainz, Germany

The latest drying trends in the area began around 1,500 years ago when archaeological and proxy records began to show definitive signs of a higher human presence on the island

While we cannot say with 100% certainty whether human activity, such as overhunting or habitat destruction, was the proverbial last drop that broke the camel’s back, our records paleoclimatic clearly show that megafauna survived all previous episodes even greater aridity This resilience to past climatic fluctuations suggests that an additional stressor has contributed to the elimination of the region’s megafauna « 

« Many pieces are still missing to fully solve the enigma of the megafauna collapse This study now provides an important multi-millennial climate backdrop to the megafaunal extinction, » said Ny Rivao Voarintsoa of KU Leuven in Belgium, from Madagascar, who also contributed to this study

The study highlights the decimation of flora and fauna of Mauritius and Rodrigues: “The two islands were rapidly stripped of endemic vertebrate species within two centuries of initial human colonization, including the well-known flightless’ Dodo ‘bird of Mauritius and the’ giant tortoise of Rodrigues’ endemic to Rodrigues’ saddleback ”, added Aurele Anquetil André, head of the reserve and chief curator of the giant turtle reserve and François Leguat caves in Rodrigues

« The story our data tells is one of the resilience and adaptability of island ecosystems and wildlife to endure past episodes of violent climate change for eons – until they are. hit by human activities and climate change, « the researchers concluded

Li, H, et al (2020) A multimillennial climate context for megafaunal extinctions in Madagascar and the Mascarenes Scientific progress https: // doiorg / 101126 / sciadvabb2459

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Extinction, megafauna, climate change

EbeneNews – AU – A study investigates the factors responsible for the extinction of Madagascar’s megafauna



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