Ancient Connection Between the Americas Caused a Surge in Biodiversity 20 Million Years Ago

A new study may reveal an unprecedented surge in biodiversity that occurred 20 million years ago. Researchers have discovered that species migrations across the Isthmus of Panama began during this time period, which is six times earlier than commonly assumed.

"Even organisms that need very specific conditions to survive, such as salamanders and freshwater fishes, crossed the Isthmus of Panama over 6 million years ago," said Christine Bacon, one of the researchers, in a news release. "These early migrations impact our understanding of how and when biodiversity in the Americas took shape."

The Isthmus of Panama links North and South America. It plays a crucial role in the planet's atmospheric and ocean circulation. Despite its importance across multiple disciplines, though, the timing of its formation and the effect that it had on the continents' biodiversity has remained controversial.

In this latest study, the researchers examined a large number of molecular studies and fossils, including land and aquatic organisms. Models based on molecular genetic data indicated that rather than one great migration following a set closure time, there were several periods in which animals and plants moved across the intercontinental land bridge. There were also shifts in the rate of movement of animal fossils moving from North America to South America at 23 million and within the past 10 million years.

The researchers also compared the proportion of immigrants in each direction to sea level and global mean temperature. This revealed that migrations may have coincided with low sea levels.

The findings reveal a bit more about the rise of the Isthmus. This is especially important to know for evolutionary biologists, who want to understand how species of marine organisms diverged and when species of terrestrial organisms moved from one continent to another.

The findings are published in the journal Proceedings of the National Academy of Sciences.

For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).