Ancient Insects Provide Clue to Biodiversity 50 Million Years Ago

About 50 million years ago, the Earth swarmed with a vast array of species. Ancient insects and other creatures thrived in a tropical mountain environment that extended up into modern-day Canada. Yet this species diversity didn't last; in modern times, there are far fewer species than there once were.

Before now, why this was the case was unconfirmed. Now, scientists, including Bruce Archibald, Rolf Mathewes and David Greenwood, have discovered evidence that shows global biodiversity was far greater in ancient times than now. The findings, published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology, examined fossil beds across a few thousand miles of the ancient mountains of British Columbia and Washington.

About 45 years ago, an evolutionary biologist theorized that the change in species from site to site across mountain ranges in the tropics should be greater than in temperate latitudes. The reasoning was that the great difference in temperate latitude seasons offered a wide window to migrate across mountainous regions, while the small difference in the tropics allowed a very narrow opportunity. Therefore, communities across tropical mountains should have fewer of the same species.

By studying the fossil beds, the researchers found that insect species in particular changed greatly across British Columbia's and Washington State's ancient mountain ranges--just like in the modern tropics. This helped actually confirm that, in fact, the seasonality hypothesis was correct.

"We found that insect species changed greatly across British Columbia's and Washington State's ancient mountain ranges, like in the modern tropics," said Archibald in a press release.

This study in particular shows that seasonality greatly affects diversity pattern. Not only that, it shows that ancient Earth had far more biodiversity than it does today. Because of these findings, scientists can better understand how life has changed on our planet.