Colombian megafauna experienced "waves" of extinctions

Spores of coprophilous fungi pass through the guts of megafauna (animals weighing over 45 kilograms) as part of their life cycle. As a result,  the presence of such spores in sediment samples can provide evidence that large animals lived in a specific time and place. 

By analyzing samples from a peat bog in Pantano de Monquentiva – located about 60 kilometers from Bogota, Colombia in the Eastern Cordillera mountains – a team of researchers from the University of Exeter discovered that large animals became locally extinct at this location both around 23,000 years ago and 11,000 years ago, severely impacting the ecosystems in which they were embedded. 

Considering our current biodiversity crisis, these findings suggest that the disappearance of large animals could once more transform ecosystems that sustain both wildlife and humans.

“We know that large animals such as elephants play a vital role in regulating ecosystems, for example by eating and trampling vegetation,” said study senior author Dunia H. Urrego, a senior lecturer in Physical Geography at Exeter.

“By analyzing samples of fungal spores, as well as pollen and charcoal, we were able to track the extinction of large animals, and the consequences of this extinction for plant abundance and fire activity. We found the Monquentiva ecosystem changed dramatically when large animals disappeared, with different plant species thriving and wildfires increasing.”

Although the analysis of fungal spores does not show which types of megafauna were present, species known to inhabit Columbia during these periods included the giant armadillo and the giant, six-meter-tall ground sloth. 

According to the researchers, most of the plentiful megafauna that existed for thousands of years vanished 23,000 years ago. After about 5,000 years, large animals began once more to populate the Monquentiva, before another wave of extinction decimated them approximately 11,000 years ago. While the causes of these extinctions are not yet clear, scientists argue that climate change, hunting by humans, or even meteor strikes could be plausible explanations. 

“After the megafauna vanished, plant species at Monquentiva transitioned, with more woody and palatable plants (those favored by grazing animals), and the loss of plants that depend on seed dispersal by animals,” said lead author Felix Pym, a graduate student in Physical Geography at Exeter.

“Wildfires became more common after the megafauna extinctions – presumably because flammable plants were no longer being eaten or trampled upon. Overall, our findings show that this habitat was highly sensitive to the decline of its megafaunal populations.”

The findings suggest that, in the context of our current biodiversity crisis, conservation efforts should take into account the effects of local herbivore declines on the dispersal of various plant species, wildfire activity, and the loss of ecosystem services.

The study is published in the journal Quaternary Research.

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By Andrei Ionescu, Earth.com Staff Writer

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