Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Low level of extinction during ice age linked to adaptability

26.04.2005


A Johns Hopkins University graduate student may have figured out why rates of extinction were so low for many of the major groups of marine life during one of the greatest ice ages of them all, which occurred from about 330 million to 290 million years ago, late in the Paleozoic Era.



The likely answer: because those aquatic life forms that did survive during this era were singularly equipped to endure severe fluctuations in temperature and sea levels. Those that were not died in a mass extinction that heralded the ice age’s onset. "These results not only clue us in to what happened many millions of years ago, but they also have implications for understanding the modern marine ecosystem," said Matthew Powell, a doctoral candidate in the Morton K. Blaustein Department of Earth and Planetary Sciences at The Johns Hopkins University’s Zanvyl Krieger School of Arts and Sciences. His paper on the topic appears in the May issue of Geology, published by the Geological Society of America.

"If the patterns I detected also are true for the modern ice age -- and other researchers’ results suggest that they may be -- then modern marine life ought to be relatively resistant to extinction," he said. "Yet species are dying off at an alarming rate. It may be that humans have altered the environment so much that we are now causing the extinction of species that should be relatively immune. Though it’s difficult to say exactly what the implications are for the world we live in, what I can say is that it is worrisome."


Powell looked at extinctions during an age when glaciers reached to within 35 degrees of the equator, roughly as far south as a line between present-day Raleigh, Memphis and Albuquerque or nearly as far north as Buenos Aires. Powell tackled the question of why extinction rates were so low during that great ice age by closely examining geographic patterns of evolution and extinction in brachiopods, simple shelled sea creatures that were abundant and well-fossilized during the Paleozoic. He constructed a database that charted latitudinal patterns of evolution and extinction through the late Paleozoic. "This database is the first ever; no other database of this kind exists for any interval of geologic time, from which to study geographic patterns of macroevolution," Powell said.

According to Powell’s analysis, brachiopods that lived primarily near the equator suffered the highest extinction rates and did not re-appear in great numbers until the ice age ended. "The absence of these particular brachiopods during the ice age left the oceans populated almost entirely with those who lived over a wider geographic area," Powell said. "What I found is that the uniquely low global rates of evolution and extinction for brachiopods during the late Paleozoic ice age were caused by the loss and lack of recovery of those that had existed in narrow latitudinal ranges."

Powell believes that those brachiopods that existed within narrow latitudinal ranges became victims of the extremes in the annual minimum and maximum temperatures that were typical of the late Paleozoic. During that era, "seasonality" -- the difference between annual temperatures’ highs and lows -- was amplified by the presence of glaciers. "I’ve suggested that those brachiopods which eventually became extinct had adapted only to small temperature changes, and thus did not survive," he said. "The other competing hypothesis is that large fluctuations of sea level, driven by the melting and reforming of glaciers, disrupted marine communities, and the ones which survived were those able to adjust.

Lisa De Nike | EurekAlert!
Further information:
http://www.jhu.edu

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Researchers shoot for success with simulations of laser pulse-material interactions

29.03.2017 | Materials Sciences

Igniting a solar flare in the corona with lower-atmosphere kindling

29.03.2017 | Physics and Astronomy

As sea level rises, much of Honolulu and Waikiki vulnerable to groundwater inundation

29.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>