Navigation Links
Low level of extinction during ice age linked to adaptability

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 abun dant 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.


Source:Johns Hopkins University

Related biology news :

1. Unprecedented water level rise in Somalia
2. New lab technique identifies high levels of pathogens in therapy pool
3. Findings have implications for tracking disease, drugs at the molecular level
4. At the molecular level, the predator is the prey
5. Scientists at Galileo Pharmaceuticals confirm inflammatory response linked to glucose levels
6. MERIS monitoring tracks planetary photosynthesis levels
7. ‘Blue Brain?project explores thought at molecular level
8. Scientists find evidence of catastrophic sand avalanches, sea level changes in Gulf of Mexico
9. High carbon dioxide levels spur Southern pines to grow more needles
10. Enzyme affects hypertension by controlling salt levels in body
11. Field tested: Grasslands wont help buffer climate change as carbon dioxide levels rise
Post Your Comments:

(Date:11/12/2015)... , Nov. 11, 2015   Growing need ... analytical tools has been paving the way for ... determination of discrete analytes in clinical, agricultural, environmental, ... being predominantly used in medical applications, however, their ... sectors due to continuous emphasis on improving product ...
(Date:11/10/2015)... , Nov. 10, 2015 ... behavioral biometrics that helps to identify and verify ... Signature is considered as the secure and accurate ... identification of a particular individual because each individual,s ... accurate results especially when dynamic signature of an ...
(Date:11/4/2015)... , November 4, 2015 ... new market report published by Transparency Market Research "Home Security ... Trends and Forecast 2015 - 2022", the global home security ... 30.3 bn by 2022. The market is estimated to ... period from 2015 to 2022. Rising security needs among ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... ... November 24, 2015 , ... International ... and one of the premier annual events for pharmaceutical manufacturing: 2015 Annual Meeting. ... 2015, where ISPE hosted the largest number of attendees in more than a ...
(Date:11/24/2015)... ... , ... This fall, global software solutions leader SAP and AdVenture Capital brought ... pitch their BIG ideas to improve health and wellness in their schools. , Now, ... the title of SAP's Teen Innovator, an all-expenses paid trip to Super Bowl 50, ...
(Date:11/24/2015)... , Nov. 24, 2015  Tikcro Technologies Ltd. (OTCQB: TIKRF) today announced ... 29, 2015 at 11:00 a.m. Israel time, at ... 98 Yigal Allon Street, 36 th Floor, Tel Aviv, ... Eric Paneth and Izhak Tamir to the Board of ... as external directors; , approval of an amendment to certain terms ...
(Date:11/24/2015)... ... November 24, 2015 , ... InSphero AG, the leading supplier of easy-to-use ... promoted Melanie Aregger to serve as Chief Operating Officer. , Having joined ... management team and was promoted to Head of InSphero Diagnostics in 2014. ...
Breaking Biology Technology: