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Richard Lenski has been growing cultures of Escherichia coli for 21 years representing about 40,000 generations. A new paper published in Nature provides details about genetic changes occurring during evolution, which can be divided into slow adaptive mutations and faster random changes.
Sequencing genomes of various generations of the bacteria, which had been frozen periodically over the years, Lenski and his team found that adaptive and random genomic changes don't necessarily follow the same patterns. Rather than a plodding equilibrium, even in a consistent environment, the interplay between these two kinds of genomic changes "is complex and can be counterintuitive," Lenski said in a prepared statement.
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The new data "beautifully emphasize the succession of mutational events that allowed these organisms to climb toward higher and higher efficiency in their environment," Dominique Schneider of the Université Joseph Fourier in Grenoble, France, and a coauthor on the paper, said in a prepared statement.
ht*p://w*w.scientificamerican.com/blog/post.cfm?id=evolution-details-revealed-through-2009-10-18
Abstract
Genome evolution and adaptation in a long-term experiment with Escherichia coli
The relationship between rates of genomic evolution and organismal adaptation remains uncertain, despite considerable interest. The feasibility of obtaining genome sequences from experimentally evolving populations offers the opportunity to investigate this relationship with new precision. Here we sequence genomes sampled through 40,000 generations from a laboratory population of Escherichia coli. Although adaptation decelerated sharply, genomic evolution was nearly constant for 20,000 generations. Such clock-like regularity is usually viewed as the signature of neutral evolution, but several lines of evidence indicate that almost all of these mutations were beneficial. This same population later evolved an elevated mutation rate and accumulated hundreds of additional mutations dominated by a neutral signature. Thus, the coupling between genomic and adaptive evolution is complex and can be counterintuitive even in a constant environment. In particular, beneficial substitutions were surprisingly uniform over time, whereas neutral substitutions were highly variable.
ht*p://w*w.nature.com/nature/journal/vaop/ncurrent/full/nature08480.html
Who was it said you can't get beneficial mutations? Who said 'new information' couldn't get into the genome? Who said all mutations are deleterious?
I read about this in "The Greatest Show on Earth", I found it really interesting and a powerful put down to the irreducible complexity argument.
On a side note the correspondence between Richard Lenski and Andy Schlafly of the Conservapedia. Is uber funny. I haven’t got time to summarise it now and its probably better that you read it in full.
Here is a good place to start its more about the second letter but it has links to what happened previously
Ok so I cant post links yet so just google “Lenski gives Conservapædia a lesson”
I read about this in "The Greatest Show on Earth", I found it really interesting and a powerful put down to the irreducible complexity argument.
On a side note the correspondence between Richard Lenski and Andy Schlafly of the Conservapedia. Is uber funny. I haven’t got time to summarise it now and its probably better that you read it in full.
Here is a good place to start its more about the second letter but it has links to what happened previously
Ok so I cant post links yet so just google “Lenski gives Conservapædia a lesson”
__________________ No silicon heaven? Where would all of the calculators go?
Kryton
Courage is the price that life exacts for granting peace. The soul that knows it not, knows no release from little things; Knows not the livid loneliness of fear, nor mountain hights where bitter joy can hear the sound of wings. How can life grant us boon of living, compensate for dull gray ugliness and pregnant hate unless we dare the soul's dominion? Each time we make a choice, we pay with courage to behold restless day, and count it fair.
Amelia Earhart
Conservapedia? I always thought they were satire, like Landover Baptist.
__________________ Creationism has not made a single contribution to agriculture, medicine, conservation, forestry, pathology, or any other applied area of biology. Creationism has yielded no classifications, no biogeographies, no underlying mechanisms, no unifying concepts with which to study organisms or life. - Botanical Society of America's Statement on Evolution
Richard Lenski has been growing cultures of Escherichia coli for 21 years representing about 40,000 generations. A new paper published in Nature provides details about genetic changes occurring during evolution, which can be divided into slow adaptive mutations and faster random changes.
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Last edited by godsmission; 22nd October 2009 at 02:43 PM.
Conservapedia? I always thought they were satire, like Landover Baptist.
Only if you count it as self parody. They are quite serious in there beliefs. They are even undertaking to re-interpret the bible in order to remove any "Liberal" ideology that might have crept in.
__________________ No silicon heaven? Where would all of the calculators go?
Kryton
Courage is the price that life exacts for granting peace. The soul that knows it not, knows no release from little things; Knows not the livid loneliness of fear, nor mountain hights where bitter joy can hear the sound of wings. How can life grant us boon of living, compensate for dull gray ugliness and pregnant hate unless we dare the soul's dominion? Each time we make a choice, we pay with courage to behold restless day, and count it fair.
Amelia Earhart
I learned about the ongoing twenty year E. coli experiment that Dr. Lenski is conducting Michigan State University while reading "The Greatest Show on Earth" as well. Fascinating. 45,000 generations!
__________________ We are surrounded by endless forms, most beautiful and most wonderful, and it is noaccident, but the direct consequence of evolution by non-random natural selection - the only game in town, the greatest show on Earth. ~R.D.
But other species are supposed to have evolved far more and they don't even have enough generations available to do it in, humans, for example. Between humans and a putative human-ape ancestor ten million years ago there are a maximum of perhaps one million generations, depending on the reproductive age at different stages. During that e-coli experiment, there was time for 653 mutations by generation 40,000, the later ones being mostly not helpful to the bacteria, divide 1 million generations by 40,000 we get 25 minor changes (eg. the abilty to digest something not previously able to handle), surely at a minimum to go from ape ancestor to human would take some 30 million minor changes, or 19,590,000,000 mutations, according to that experiment, there would happen only 16,325 mutations during that amount of time. Is it possible?
Linear Mode
