Navigation Links
No peak in sight for evolving bacteria

There's no peak in sight fitness peak, that is for the bacteria in Richard Lenski's Michigan State University lab.

Lenski, MSU Hannah Distinguished Professor of Microbiology and Molecular Genetics, has been running his evolutionary bacteria experiment for 25 years, generating more than 50,000 generations. In a paper published in the current issue of Science, Michael Wiser, lead author and MSU graduate student in Lenski's lab, compares it to hiking.

"When hiking, it's easy to start climbing toward what seems to be a peak, only to discover that the real peak is far off in the distance," Wiser said. "Now imagine you've been climbing for 25 years, and you're still nowhere near the peak."

Only the peaks aren't mountains. They are what biologists call fitness peaks when a population finds just the right set of mutations, so it can't get any better. Any new mutation that comes along will send things downhill.

The bacteria in Lenski's lab are still becoming more fit even after a quarter century, living in the same, simple environment.

Biologists have known that organisms keep evolving if the environment keeps changing, but they've previously thought that adaptation would eventually grind to a halt if the environment stayed constant for a long time.

Wiser pulled hundreds of samples from the deep freezer that contains a frozen fossil record bacteria all the way back to generation 0 in Lenski's 25-year experiment. And these fossils, unlike dinosaurs, are alive. So they can be competed against samples from different generations to measure the trajectory the path of the bacteria as they climbed for 50,000 generations toward the fitness peaks.

"There doesn't seem to be any end in sight," Lenski said. "We used to think the bacteria's fitness was leveling off, but now we see it's slowing down but not really leveling off."

Wiser found that the trajectories matched a type of mathematical function called a power law. Although the slope of the power-law function gets less and less steep over time, it never reaches a peak.

Noah Ribeck, co-author and MSU postdoctoral researcher, built a model using a few well-understood principles.

"It was surprising to me that a simple theory can describe the entirety of a long evolutionary trajectory that includes initially fast and furious adaptation that later slowed to a crawl," Ribeck said. "It's encouraging that despite all the complications inherent to biological systems, they are governed by general principles that can be described quantitatively."

When will it end?

"I call this the experiment that keeps on giving," Lenski said. "Even after 25 years, it's still generating new and exciting discoveries. From the models, we can predict how things will evolve how fit the bacteria will become if future generations of scientists continue the experiment long after I'm gone."

Lenski hopes that an endowment could be secured to keep the experiment going forever, he added.


Contact: Layne Cameron
Michigan State University

Related biology news :

1. OHSU Vollum Institute research gives new insight into how antidepressants work in the brain
2. Global map provides new insights into land use
3. Physicists provide new insights into coral skeleton formation
4. New insights into DNA repair process may spur better cancer therapies
5. Erratic proteins: New insights into a transport mechanism
6. Eyewear Market 2014 Insights and System Refresher Report
7. Global analysis reveals new insights into the ribosome -- with important implications for disease
8. Potential diagnostic marker for zinc status offers insights into the effects of zinc deficiency
9. Unprecedented control of genome editing in flies promises insight into human development, disease
10. Better insight into molecular interactions
11. New insights into neuroblastoma tumor suppressor may provide clues for improved treatment
Post Your Comments:
(Date:11/18/2015)... , November 18, 2015 ... published a new market report titled  Gesture Recognition Market ... Forecast, 2015 - 2021. According to the report, the global gesture ... is anticipated to reach US$29.1 bn by 2021, at ... North America dominated the global ...
(Date:11/17/2015)... Nov. 17, 2015  Vigilant Solutions announces today that ... Board of Directors. --> ... retiring from the partnership at TPG Capital, one of ... over $140 Billion in revenue.  He founded and led ... the TPG companies, from 1997 to 2013.  In his ...
(Date:11/12/2015)... Nov. 12, 2015  A golden retriever that stayed ... dystrophy (DMD) has provided a new lead for treating ... the Broad Institute of MIT and Harvard and the ... . Cell, pinpoints a protective ... the disease,s effects. The Boston Children,s lab of ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... 25, 2015  Neurocrine Biosciences, Inc. (Nasdaq: NBIX ... and CEO of Neurocrine Biosciences, will be presenting at ... New York . .   ... approximately 5 minutes prior to the presentation to download ... presentation will be available on the website approximately one ...
(Date:11/25/2015)... , ... November 25, 2015 , ... ... uBiome, were featured on AngelList early in their initial angel funding process. Now, ... syndicate for individuals looking to make early stage investments in the microbiome space. ...
(Date:11/24/2015)... 24, 2015 /CNW/ - iCo Therapeutics ("iCo" or "the ... results for the quarter ended September 30, 2015. ... dollars and presented under International Financial Reporting Standards ... ," said Andrew Rae , President & ... are not only value enriching for this clinical ...
(Date:11/24/2015)... PUNE, India , November 24, 2015 ... to a new market research report "Oligonucleotide Synthesis Market ... Equipment), Application (PCR, Gene Synthesis, Diagnostic, DNA, RNAi), End-User ... to 2020", published by MarketsandMarkets, the market is expected ... 1,078.1 Million in 2015, at a CAGR of 10.1% ...
Breaking Biology Technology: