Evolution imposes 'speed limit' on recovery after mass extinctions

Evolution imposes 'speed limit' on recovery after mass extinctions
An artist's interpretation of the sea floor after the mass extinction that wiped out the dinosaurs. The three hair-covered forms (left) represent species of plankton that survived. The geometric form (bottom left) is a species of algae. Credit: The University of Texas at Austin Jackson School of Geosciences/John Maisano

It takes at least 10 million years for life to fully recover after a mass extinction, a speed limit for the recovery of species diversity that is well known among scientists. Explanations for this apparent rule have usually invoked environmental factors, but research led by The University of Texas at Austin links the lag to something different: evolution.

The recovery limit has been observed across the fossil record, from the "Great Dying" that wiped out nearly all ocean life 252 million years ago to the massive asteroid strike that killed all nonavian dinosaurs. The study, published April 8 in the journal Nature Ecology & Evolution, focused on the later example. It looks at how life recovered after Earth's most recent , which snuffed out most dinosaurs 66 million years ago. The asteroid impact that triggered the is the only event in Earth's history that brought about faster than present-day climate change, so the authors said the study could offer important insight on recovery from ongoing, human-caused extinction events.

The idea that evolution—specifically, how long it takes surviving species to evolve traits that help them fill open ecological niches or create new ones—could be behind the extinction recovery speed limit is a theory proposed 20 years ago. This study is the first to find evidence for it in the , the researchers said.

The team tracked recovery over time using fossils from a type of plankton called foraminifera, or forams. The researchers compared foram diversity with their physical complexity. They found that total complexity recovered before the number of species—a finding that suggests that a certain level of ecological complexity is needed before diversification can take off.

Evolution imposes 'speed limit' on recovery after mass extinctions
Lead author Chris Lowery, a research associate at the University of Texas at Austin, examining microfossils on the scientific drilling mission that retrieved core samples from the crater left by the dino-killing asteroid. Credit: The UT Jackson School of Geosciences/Chris Lowery.

In other words, mass extinctions wipe out a storehouse of evolutionary innovations from eons past. The speed limit is related to the time it takes to build up a new inventory of traits that can produce new species at a rate comparable to before the extinction event.

Lead author Christopher Lowery, a research associate at the University of Texas Institute for Geophysics (UTIG), said that the close association of foram complexity with the recovery speed limit points to evolution as the speed control.

"We see this in our study, but the implication should be that these same processes would be active in all other extinctions," Lowery said. "I think this is the likely explanation for the speed limit of recovery for everything."

Lowery co-authored the paper with Andrew Fraass, a research associate at the University of Bristol who did the research while at Sam Houston State University. UTIG is a research unit of the UT Jackson School of Geosciences.

Evolution imposes 'speed limit' on recovery after mass extinctions
A photomicrograph showing 10 species of foraminifera, a type of plankton. In this paper, researchers examined foraminifera fossils and found a link between the rate of species recovery after an extinction event and evolution. Credit: United States Geological Survey/l Randolph Femmer

The researchers were inspired to look into the link between recovery and evolution because of earlier research that found recovery took millions of years despite many areas being habitable soon after Earth's most recent mass extinction. This suggested a control factor other than the environment alone.

They found that although foram diversity as a whole was decimated by the asteroid, the species that survived bounced back quickly to refill available niches. However, after this initial recovery, further spikes in species diversity had to wait for the evolution of new traits. As the speed limit would predict, 10 million years after extinction, the overall diversity of forams was nearly back to levels observed before the extinction event. Foram fossils are prolific in ocean sediments around the world, allowing the researchers to closely track species diversity without any large gaps in time.

Earth's recovery from mass extinction could take millions of years
Figure showing the very diverse late Cretaceous planktic foraminifera, the very small and simple group that survives the extinction, and then the increasing diversity of shapes in this group of plankton as they recover during the early Paleogene. Credit: Christopher Lowery

Pincelli Hull, an assistant professor at Yale University, said the paper sheds light on factors driving recovery.

"Before this study, people could have told you about the basic patterns in diversity and complexity, but they wouldn't have been able to answer how they relate to one another in a quantitative sense," she said.

The authors said that recovery from past extinctions offers a road map for what might come after the modern ongoing extinction, which is driven by climate change, habitat loss, invasive and other factors.

Explore further

Fossils show recovery from extinction event helped shape evolutionary history

More information: Morphospace expansion paces taxonomic diversification after end Cretaceous mass extinction, DOI: 10.1038/s41559-019-0835-0 , https://www.nature.com/articles/s41559-019-0835-0
Journal information: Nature Ecology & Evolution

Citation: Evolution imposes 'speed limit' on recovery after mass extinctions (2019, April 8) retrieved 20 August 2019 from https://phys.org/news/2019-04-evolution-imposes-limit-recovery-mass.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Apr 08, 2019
The only problem with this theory is that the speed of light is not a constant. It also was hundreds of thousands of times faster a few millennia ago and is only now starting to taper off. This throws carbon dating off and means the earth is not billions of years old but only a 10-20 thousand years old... scientists refuse to accept this challenge to their 'dogma' much like the discovery that the world is not flat, and the earth is not the center of the universe. This childish behavior by the supposedly elite of the scientific community is troubling and also shows their inability to think for themselves when faced with hard evidence. Which is something they berate the 'non-scientific' community constantly for...

Apr 08, 2019
The only problem with this theory is that the speed of light is not a constant. It also was hundreds of thousands of times faster a few millennia ago and is only now starting to taper off.

Utter crap. Point to this finding in the scientific literature. Do not link to creationist crap, or it will be reported.

Apr 08, 2019
The speed of light has absolutely NOTHING to do with this article. Nothing.

Anyone making extraordinary claims, for example... "the speed of light is not constant", needs extraordinary evidence. Name calling and invective nastiness may be emotionally satisfying to the crackpot slinging mud, but it hardly amounts to evidence.

Apr 08, 2019
Estimates from extinctions has diversity recovery on the order of 1 Myrs for smaller ones and 10 Myrs for larger ones; this confirms the latter.

Since we now seem to live in the 6th major extinction, this means that we, or our immediate descendants, won't see the diversity recovery - the average lifetime of a mammal species is on the order of 1 Myrs.

The "complexity before diversity" theme is consistent with the Ediacaran and Cambrian diversifications, where IIRC gene regulation and transcriptome diversification are believed to have underlie complexity. Those happened on a similar time scale (perhaps 20 Myrs for the Lantian diversification, 40 Myrs for the Cambrian).

Apr 08, 2019
The speed of light has absolutely NOTHING to do with this article.

FWIW, I believe blocked that crackpot at the speed of light; his first sentence oozed of troll bridge mold - no need to read (and thx to sensible comments, no need to respond to the crap).

How hard can it be to distinguish between *biology* and *physics*, for starters?

Apr 08, 2019
The only problem with this theory is that the speed of light is not a constant. ...

Turned down for yet another doctoral program, eh? Well, same time tomorrow - you're bound to get a winner one of these days..!

(P.S. - this would have sounded a lot better if you'd mentioned at least two of:
- alien visitors
- creationism
- intelligent design
- intelligent aliens
- designing aliens
- visitational creators
- aliens at the well of souls
- Barbie - because everything goes better with Barbie

Oh, and - no need to say "They all thought I was mad! Well, I'll show them! Ah-ha-ha-ha-ha-ha! Ah-ha-ha-ha-ha-ha! Ah-ha-ha-ha-ha-ha-ha-ha-ha-ha!!!!!". You already have. Ta!)

Apr 08, 2019
10M years isn't that long. Considering some of these life-groups lasted 200M years. Mass extinction really isn't a logical term since there never was (that we know of) any Earth-wide total extinction of higher forms.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more