Mass Extinctions Set the Pace

The rate of evolution is affected for millenia after mass extinctions.

By Hayley Dunning | July 4, 2012



Mass extinction events empty many ecological niches, usually leading to explosions in speciation as new groups of organisms rush to claim them. It is commonly assumed that after this initial growth, the number of new species evolving declines back to a normal rate. However, a new analysis published last week (June 30) in Geology suggests that new, often faster rates of speciation prevail for hundreds of years after widespread extinctions.

“Things don’t return to what they were before,” study co-author Andrew Krug said in a press release. “They operate at a different pace, sometimes more rapidly, other times more slowly.” The new pace also seems to be permanent, until the next mass extinction.

The team looked into the diversity of bivalves, the group of mollusks that includes clams and oysters, from the start of the Jurassic period, 200 million years ago, to the end of the Pleistocene Epoch, just 10,000 years ago. The bivalve groups evolved at steady rates for millions of years, but that rate shifted dramatically in step with mass extinctions, in a pattern co-author David Jablonski described as “surprisingly organized.”

Add a Comment

Avatar of: You



Sign In with your LabX Media Group Passport to leave a comment

Not a member? Register Now!

LabX Media Group Passport Logo


Avatar of: rhansing


Posts: 20

July 5, 2012

Interesting.... the question is why???? No competition? any other ideas?

Avatar of: steinp2


Posts: 33

July 5, 2012

It's like opening the doors to Walmart at midnight on Black Friday.  The results are often not pretty.

Paul M. Stein

Avatar of: rhansing


Posts: 20

July 6, 2012

thanks... this is amazing research... and quite innovative... Ahhh,... the wonders of science. i love it.

July 6, 2012

 Follow the link:

"Krug and Jablonski’s suggestion that the potential for rapid speciation and expansion of survivors and new groups of organisms in the “emptierâ€쳌 world following a mass extinction “is a reasonable possibility as one source of rate change,â€쳌 said paleontologist Richard Bambach of the Smithsonian Museum of Natural History, who was not directly involved in the UChicago study."

“No one has really thought about it in terms of these downstream dynamics, once the smoke has cleared and ecosystems have found a new equilibrium, for want of a better word. But the wonderful thing is that when they find a new equilibrium, it’s a different evolutionary pace from the one that prevailed for the preceding 50 million years. The survivors of the mass extinction, or the world they inherited, is so different from what went before that the rate of evolution is permanently changed.â€쳌

July 6, 2012

 To expand, it isn't only lack of competition, but perhaps also lack of ecological niches that makes for rapid speciation.

Avatar of: Donkie421


Posts: 1457

July 8, 2012

mass extinctions happens once in a while after a million of years. what happens if extinctions happens more moderately? 

Popular Now

  1. Elena Rybak-Akimova, Chemical Kinetics Expert, Dies
  2. University of Oregon Erecting a $1-Billion Science Center
  3. Could Rapamycin Help Humans Live Longer?
  4. Investigation Finds Signs of Misconduct in Swedish Researcher’s Papers