Earth’s ancient marine life could reveal what triggers mass extinctions

WASHINGTON - A new study has found that an influx of invasive species can hinder the natural evolution of new species and trigger mass extinction events.

Scientists at Ohio University studied the collapse of Earth’s marine life 378 to 375 million years ago and found that the planet’s current ecosystems, which are struggling with biodiversity loss, could meet a similar fate.

“We refer to the Late Devonian as a mass extinction, but it was actually a biodiversity crisis,” said Alycia Stigall.

“The knowledge is critical to determining the cause and extent of mass extinctions through time, especially the five biggest biodiversity crises in the history of life on Earth. It provides an important perspective on our current biodiversity crises,” she added.

Results indicate that vicariance - the typical method by which new species originate - was absent during this ancient phase of Earth’s history, and could be to blame for the mass extinction.

New species also can originate through dispersal, which occurs when a subset of a population moves to a new location.

The study analysed on one bivalve, Leptodesma (Leiopteria), and two brachiopods, Floweria and Schizophoria (Schizophoria), as well as a predatory crustacean, Archaeostraca.

When sea levels began rising, some species gained access to environments they hadn’t inhabited before. The hardiest of these invasive species that could thrive on a variety of food sources and in new climates became dominant, wiping out more locally adapted species.

Of the species Stigall studied, most lost substantial diversity during the Late Devonian, and one, Floweria, became extinct. The giant fishes, trilobites, sponges and brachiopods also declined dramatically, while organisms on land had much higher survival rates.

“Even if you can stop habitat loss, the fact that we’ve moved all these invasive species around the planet will take a long time to recover from because the high level of invasions has suppressed the speciation rate substantially,” Stigall said.

“The more we know about this process,” Stigall said, “the more we will understand how to best preserve biodiversity.”

The research results are published today in the journal PLoS ONE. (ANI)