Featured Research

from universities, journals, and other organizations

Family Trees Of Ancient Bacteria Reveal Evolutionary Moves

Date:
February 16, 2005
Source:
Washington University In St. Louis
Summary:
A geomicrobiologist at Washington University in St. Louis has proposed that evolution is the primary driving force in the early Earth's development rather than physical processes, such as plate tectonics.

A hot spring at old faithful in Yellowstone National Park, Wyoming. A WUSTL scientist suggests that Cyanobacteria arose in freshwater environments rather than in the sea.
Credit: Photo Carrine Blank/WUSTL Photo

Feb. 2, 2005 — A geomicrobiologist at Washington University in St. Louis has proposed that evolution is the primary driving force in the early Earth's development rather than physical processes, such as plate tectonics.

Carrine Blank, Ph.D., Washington University assistant professor of geomicrobiology in the Department of Earth & Planetary Sciences in Arts & Sciences, studying Cyanobacteria - bacteria that use light, water, and carbon dioxide to produce oxygen and biomass - has concluded that these species got their start on Earth in freshwater systems on continents and gradually evolved to exist in brackish water environments, then higher salt ones, marine and hyper saline (salt crust) environments.

Cyanobacteria are organisms that gave rise to chloroplasts, the oxygen factory in plant cells. A half billion years ago Cyanobacteria predated more complex organisms like multi-cellular plants and functioned in a world where the oxygen level of the biosphere was much less than it is today. Over their very long life span, Cyanobacteria have evolved a system to survive a gradually increasing oxidizing environment, making them of interest to a broad range of researchers.

Blank is able to draw her hypothesis from family trees she is drawing of Cyanobacteria. Her observations are likely to incite debate among biologists and geologists studying one of Earth's most controversial eras - approximately 2.1 billion years ago, when cyanobacteria first arose on the Earth. This was a time when the Earth's atmosphere had an incredible, mysterious and inexplicable rise in oxygen, from extremely low levels to 10 percent of what it is today. There were three - some say four - global glaciations, and the fossil record reflects a major shift in the number of organisms metabolizing sulfur and a major shift in carbon cycling.

"The question is: Why?" said Blank.

"My contribution is the attempt to find evolutionary explanations for these major changes. There were lots of evolutionary movements in Cyanobacteria at this time, and the bacteria were making an impact on the Earth's development. Geologists in the past have been relying on geological events for transitions that triggered change, but I'm arguing that a lot of these things could be evolutionary."

Blank presented her research at the 2004 annual meeting of the Geological Society of America, held, Nov. 7-10 in Denver.

Blank's finding that Cyanobacteria emerged first in fresh water lakes or streams is counterintuitive.

"Most people have the assumption that Cyanobacteria came out of a marine environment - after all, they are still important to marine environments today, so they must always have been," Blank said. "When Cyanobacteria started to appear, there was no ozone shield, so UV light would have killed most things. They either had to have come up with ways to deal with the UV light - and there is evidence that they made UV-absorbing pigments - or find ways of growing under sediments to avoid the light."

To study the evolution of Cyanobacteria, Blank drew up a backbone tree using multiple genes from whole genome sequences. Additional species were added to the tree using ribosomal RNA genes. Morphological characters, for instance, the presence or absence of a sheath, unicellular or filamentous growth, the presence or absence of heterocysts — a thick-walled cell occurring at intervals — were coded and mapped on the tree. The distribution of traits was compared with those found in the fossil record.

Cyanobacteria emerging some two billion years ago were becoming complex microbes that had larger cell diameters than earlier groups - at least 2.5 microns. Blank's tree shows that several morphological traits arose independently in multiple lines, among them a sheath structure, filamentous growth, the ability to fix nitrogen, thermophily (love of heat), motility and the use of sulfide as an electron donor.

"We will need lots of analyses of the micro-fossil record by serious paleobiologists to see how sound this hypothesis is," Blank said. "This time frame is one of the biggest puzzles for biologists and geologists alike. A huge amount of things are happening then in the geological record."


Story Source:

The above story is based on materials provided by Washington University In St. Louis. Note: Materials may be edited for content and length.


Cite This Page:

Washington University In St. Louis. "Family Trees Of Ancient Bacteria Reveal Evolutionary Moves." ScienceDaily. ScienceDaily, 16 February 2005. <www.sciencedaily.com/releases/2005/02/050212185542.htm>.
Washington University In St. Louis. (2005, February 16). Family Trees Of Ancient Bacteria Reveal Evolutionary Moves. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/2005/02/050212185542.htm
Washington University In St. Louis. "Family Trees Of Ancient Bacteria Reveal Evolutionary Moves." ScienceDaily. www.sciencedaily.com/releases/2005/02/050212185542.htm (accessed July 30, 2014).

Share This




More Plants & Animals News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Rodents Rampant in Gardens Around Louvre

Rodents Rampant in Gardens Around Louvre

AP (July 29, 2014) Food scraps and other items left on the grounds by picnickers brings unwelcome visitors to the grounds of the world famous and popular Louvre Museum in Paris. (July 29) Video provided by AP
Powered by NewsLook.com
Jane Goodall Warns Great Apes Face Extinction

Jane Goodall Warns Great Apes Face Extinction

AFP (July 29, 2014) The world's great apes face extinction within decades, renowned chimpanzee expert Jane Goodall warned Tuesday in a call to arms to ensure man's closest relatives are not wiped out. Duration: 00:58 Video provided by AFP
Powered by NewsLook.com
How Your Face Can Leave A Good Or Bad First Impression

How Your Face Can Leave A Good Or Bad First Impression

Newsy (July 29, 2014) Researchers have found certain facial features can make us seem more attractive or trustworthy. Video provided by Newsy
Powered by NewsLook.com
Rat Infestation at Paris' Tuileries Garden

Rat Infestation at Paris' Tuileries Garden

AFP (July 29, 2014) An infestation of rats is causing concern among tourists at Paris' most famous park -- the Tuileries garden next to the Louvre Museum. Duration: 00:54 Video provided by AFP
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:
from the past week

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