Featured Research

from universities, journals, and other organizations

Geologist Finds Evidence That Mass Extinctions Are Not Unique In Affecting Global Diversity Trends

Date:
August 24, 1998
Source:
University Of Cincinnati
Summary:
The dramatic effects of the mass extinctions recorded in Earth's geologic record have led many geologists to view them as a distinct class of events -- so powerful that they swamp out normal evolutionary processes. Others have argued the opposite, that over geologic time, mass extinctions have had little effect on global diversity trends.

Cincinnati -- The dramatic effects of the mass extinctions recorded in Earth's geologic record have led many geologists to view them as a distinct class of events -- so powerful that they swamp out normal evolutionary processes. Others have argued the opposite, that over geologic time, mass extinctions have had little effect on global diversity trends.

Related Articles


University of Cincinnati geologist Arnold Miller argues in a review paper in the August 21 issue of Science that the truth is somewhere in the middle of those extreme views. Miller's evaluation of global marine diversity patterns through the Phanerozoic, in light of recent research, indicates that mass extinctions are simply the most globally extensive of a continuum of abrupt transitions that combine to affect overall global diversity. The Phanerozoic covers the pasts 540 million years.

That view is in contrast to Stephen Jay Gould and others who have viewed mass extinctions as an over-arching tier of evolutionary processes, distinctly different than the processes which occur in the intervening time periods.

"While I agree that mass extinctions are the largest and most important of a class of 'catastrophes,' I would argue that they are not fundamentally different as an evolutionary mechanism from what causes diversity change in the intervals between them," said Miller. "The so-called background intervals are also built of catastrophes that are more local or regional in scope, but can have the same profound effect on a local biota that a mass extinction has on a global biota."

As an example of an abrupt regional change, Miller discusses the diversification of a group of organisms known as "biological bulldozers," which dig into deposited sediments to find food. The geologic record includes cases where the bulldozers replaced another group known as ISOSS (immobile suspension feeders on soft substrates). Previously, researchers believed the biological bulldozers out-competed the ISOSS organisms. Miller suggests an alternative explanation.

"Many deposit-feeders favor muddy, nutrient-rich sediments as a substrate to occupy. Just such sediments were provided during key intervals as a consequence of eroding areas uplifted during mountain-building. Quite apart from the action of the bulldozers, many of the incumbent immobile types would not have liked this kind of habitat. So I am suggesting, as an alternative to the above 'competitive' scenario, that the transition happened because of major, physical changes to habitats."

In fact, previous research reported by Miller and others on the Ordovician Period showed that diversification of certain groups was favored in areas where active mountain-building took place.

As for those who argue that mass extinctions are actually minor contributors to global diversity patterns, Miller has used his database of Ordovician fossil occurrences to demonstrate that regional and local bursts of diversification occur at different times around the world. Over time, the bursts add up to present what Miller believes is a misleading picture of diversification trends a smooth, gradual change over geologic time.

"The global pattern does not match any localized pattern," said Miller. "The global diversity trend is misleading for what it says about the rates of transition and perhaps even for what causes them."

Miller's research is supported by NASA's Program on Exobiology.


Story Source:

The above story is based on materials provided by University Of Cincinnati. Note: Materials may be edited for content and length.


Cite This Page:

University Of Cincinnati. "Geologist Finds Evidence That Mass Extinctions Are Not Unique In Affecting Global Diversity Trends." ScienceDaily. ScienceDaily, 24 August 1998. <www.sciencedaily.com/releases/1998/08/980824072246.htm>.
University Of Cincinnati. (1998, August 24). Geologist Finds Evidence That Mass Extinctions Are Not Unique In Affecting Global Diversity Trends. ScienceDaily. Retrieved March 3, 2015 from www.sciencedaily.com/releases/1998/08/980824072246.htm
University Of Cincinnati. "Geologist Finds Evidence That Mass Extinctions Are Not Unique In Affecting Global Diversity Trends." ScienceDaily. www.sciencedaily.com/releases/1998/08/980824072246.htm (accessed March 3, 2015).

Share This


More From ScienceDaily



More Plants & Animals News

Tuesday, March 3, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Rare Goblin Shark Found in Australia

Rare Goblin Shark Found in Australia

AFP (Mar. 3, 2015) A goblin shark, a rare sea creature described as an &apos;alien of the deep&apos; is found off Australia and delivered to the Australian Museum in Sydney. Duration: 01:25 Video provided by AFP
Powered by NewsLook.com
500 Snakes Surprise Construction Workers In Canada

500 Snakes Surprise Construction Workers In Canada

Newsy (Mar. 2, 2015) Hundreds of snakes, disturbed by a construction project, were relocated to a wildlife rescue association in Canada. Video provided by Newsy
Powered by NewsLook.com
Going Gluten-Free Could Get You A Tax Break

Going Gluten-Free Could Get You A Tax Break

Newsy (Mar. 2, 2015) If a doctor advises you to remove gluten from your diet, you could get a tax deduction on the amount you spend on gluten-free foods. Video provided by Newsy
Powered by NewsLook.com
Zookeepers Copy Animal Poses In Hilarious Viral Photos

Zookeepers Copy Animal Poses In Hilarious Viral Photos

Buzz60 (Mar. 2, 2015) Zookeepers at the Symbio Wildlife Park in Helensburgh, Australia decided to take some of their favorite animal photos and recreate them by posing just like the animals. Jen Markham (@jenmarkham) has the story. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins