October 22, 1998
Contact:
Leila Belkora
(312) 996-3457
[email protected]
FOSSIL RESEARCHER CHALLENGES POPULAR IDEA OF DEVELOPMENT OF FORM THROUGH TIME
A graduate student at the University of Illinois at Chicago is challenging a popular idea that the range of physical forms exhibited by organisms of the same species decreases with time over millions of years of evolution. The idea, put forward by noted evolutionary biologist Stephen J. Gould, is that the morphology of biological groups shows "early experimentation, later standardization."
Andrea Stockmeyer Lofgren, working with advisor Roy Plotnick, professor of earth and environmental sciences at UIC, studied fossils of arthropods belonging to nearly 100 different species of the Carboniferous age (about 300 million years ago) from an area near Mazon Creek, Illinois. She assigned each specimen a score according to the presence, absence or state of 66 traits, such as number of legs or presence of antennae. From the data she determined the level of morphologic disparity, or the range of morphology in the sample of organisms.
"Morphologic disparity is becoming increasingly recognized as an important factor in understanding evolution and the development of form through time," said Lofgren. "Disparity is not the same as diversity; it has been described as a measure of the range or significance of morphology in a given sample of organisms."
Her preliminary results suggest that arthropod disparity has not decreased as much as expected since the Cambrian age about 600 million years ago, and in fact has remained nearly constant.
The researchers said the data shed new light on the question of morphologic disparity. Previous studies, supporting the idea that the range of forms decreased or stayed constant, examined arthropod disparity by comparing Cambrian and recent organisms. The current data give a snapshot of morphologic disparity at a third time.
"Conclusions from this analysis may be very significant, as they offer data from an age nearly halfway between the Cambrian and Recent studies and will offer insight into the trends of disparity through geologic time," said Lofgren.
Lofgren will present her work at the Geological Society of America's national meeting in Toronto, Oct. 26-29.
- UIC -
_________________________________________________________
October 22, 1998
Contact: Leila Belkora
(312) 996-3457
[email protected]
NEW TECHNIQUE HELPS STUDY UNDERGROUND BACTERIA,
HARNESS THEM FOR GROUNDWATER CLEAN-UP
A geologist at the University of Illinois at Chicago, together with colleagues from the Idaho National Engineering and Environmental Laboratory and Princeton University, has developed a technique to study bacteria from subsurface rock samples. The technique allows scientists to understand the bacteria's natural role and will help engineers refine the process of using bacteria to clean up polluted groundwater.
Kenneth Tobin, a UIC visiting assistant professor of earth and environmental sciences, finds bacterial cells in basalt rock samples using a chemical stain that binds with nucleic acids like DNA. When treated with the stain propidium iodide, the cells reveal their presence by emitting red light in fluorescence after being exposed to green light.
"The advantage of the technique over previous methods is that it avoids detaching the cells from their host mineral surfaces, and it avoids the problem of contaminating the rock sample with non-indigenous bacteria," said Tobin. "The protocol we've developed enables us to visualize intact microbial cells, so we can understand the context in which they grow."
Bacteria are naturally present in the aquifers that provide drinking water for about half the U.S. population. They are an integral part of the chemical processes affecting groundwater, helping to dissolve some minerals and precipitate others. Tobin expects the technique he developed with colleagues Tullis Onstott and Frederick Colwell will allow scientists to better characterize these bacteria and assess their geochemical impact.
A better understanding of the bacteria should also help scientists exploit them to clean up contaminated groundwater. Some naturally occurring bacteria break down undesirable chemicals in the groundwater, such as chlorinated organic compounds, if the bacteria are supplied with extra nutrients. The process is called biostimulation.
"It's important to know the specific ecological niche occupied by indigenous bacteria, to evaluate the potential effectiveness of remediation efforts," Tobin said.
Tobin will present the work at the Geological Society of America's national meeting in Toronto, Oct. 26-29.
- UIC -
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