Study Reveals How Galapagos Islands Developed Their Unique Biodiversity

Posted: Dec 25 2016, 5:56am CST | by , Updated: Dec 25 2016, 5:58am CST, in News | Latest Science News

 

Study Reveals How Galapagos Islands Developed their Unique Biodiversity
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The critical event that caused a biological explosion in the Galápagos occured when the Equatorial Undercurrent began colliding with the archipelago

While visiting Galapagos Islands in 1835, Charles Darwin observed a diverse range of local plants and animal species and called the archipelago a little world within itself. The islands have also inspired Darwin’s theory of evolution by natural selection. But how and when the Galapagos Islands developed their unique ecosystems is still a mystery.

A new study, however, offers more clues to the geological formation of one of the most important parts of archipelago known as Isla Isabela – the part that hosts a huge biodiversity – and researchers believe it was formed approximately 1.6 million years ago.

The Galapagos Islands may have existed in one form or another for several million years but researchers were interested in learning more about its biodiversity. They want to put finger on the geologic event or moment that turned the Galápagos from just another ordinary group of oceanic islands into one of the most biologically diverse spots in the world.

Galapagos Islands sit atop Nazca tectonic plate, off the coast of South America. The plate is slowly moving from west to east and appears to be reaching a hotspot, a point at which magma lurks under the Earth's core and form volcanic islands. 

Researchers hypothesize that biological explosion in the Galápagos was triggered by the collision of Equatorial Undercurrent (EUC) with the archipelago. Equatorial Undercurrent is a jetlike current found just below the sea surface, flowing eastward. This event alongside the extreme isolation of the islands led to the development of unusual ecosystems and biodiversity.

“That's what occurred with the Galápagos," said lead author Kris  Karnauskas from University of Colorado, Boulder. "It's a pure accident of geography that Isla Isabela is so large and stands right on the equator, right where the EUC is trying to pass through. This is enough to drive cold, nutrient-rich water up to the surface where it can fuel marine productivity. We can easily see it today from space; the water is very cold and productive just west of the Galápagos along the shores of Isabela. It's no surprise that you'll find all the penguins jumping in the water there.”

Finding out exactly when the Galápagos blocked the Equatorial Undercurrent, researchers used previously collected data from sediment cores - deep samples of the sea floor – from Galápagos Islands and South America and observed subtle chagnes in chemical composition of sediments, dating back to approximately 1.6 million years.

“Typically, we use known geologic constraints to help explain past changes in the environment such as ocean circulation," said Karnauskas. "In this case, we flipped the problem on it's head, combined models that aren't normally combined, and discovered a new constraint for piecing together the bigger picture of the evolution of, and on, the islands over time. It contributes a unique data point not only for geology but also for ecology and biogeography—where and when life is distributed."

 

 

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Hira Bashir covers daily affairs around the world.

 

 

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