May 19, 2006 2:08 PM PDT

Is evolution predictable?

Can we predict how animals and plants evolve in response to changes in the environment? Maybe, according to preliminary research from Rice University.

Associate professor Yousif Shamoo and two students recently conducted experiments on a microbe, G. stearothermophilus, to see how it adapted to different environmental circumstances. In the experiment, the dominant strains of separate generations of the microbe ended up developing the same mutant gene in response to the same environmental hazards.

Conceivably, if scientists can predict how the microbes will adapt to changes in their environment, they can develop antibiotics that won't be rapidly rendered ineffective by stronger, successive generations. In other words, if researchers can figure out what gene might evolve in response to a medicine, they can figure out a way around that response.

In the experiment, the team created a mutant strain of the microbe that was unable to live in high-temperature environments. Typically, the bacteria can continue to thrive when the temperature hits 73 degrees Celsius (163 degrees Fahrenheit). The experimental strain of bacteria contained a mutated version of a gene that, in the naturally occurring strain of the microbe, produces a protein that made existence possible.

They then put these mutant strains in environments where the temperature rose slowly but steadily, and studied how different generations coped with the changing temperature.

In the breeding that followed, millions of new mutations of the gene in question were produced, but only about 700 of those variants replicated some of the functionality of the naturally occurring gene.

One variant, called Q199R, appeared almost immediately, and the bacteria that contained it became the dominant strain of bacteria through 500 generations of breeding. The gene, however, couldn't provide protection after 62 degrees Celsius.

At that point, five new strains of bacteria, all with slightly different versions of Q199R, appeared. Three of the five new strains were driven to extinction in a few days, while the remaining two fought it out for three weeks longer.

The group then conducted the experiment again, and the same mutations developed. Thus, the experiment suggests that evolutionary development can be predicted, the researchers said.

"The duplicate study suggests that the pathways of molecular adaptation are reproducible and not highly variable under identical conditions," Shamoo said in a statement. "One of our most surprising findings is that an estimated 20 million point mutations gave rise to just six populations that were capable of vying for dominance. This suggests that very few molecular pathways are available for a specific molecular response."

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Scope of predictabililty
This is a most interesting finding. However, I would pounder it with two questions:
1 - Do we know that the mutated gene was not already present in the population?
2 - Is this possible that some gene are most likely to mutate and that some mutation are more likely, based on the mechanic of the DNA. If that so, could the presence of those loose end DNAs be itself an evolution factor?

Just the point of view of a software programmer.
Posted by rlemieux (1 comment )
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why a surprise?
but this is exactly the crux of evolution: a VERY large number of possible variants are tried, in parallel by a population, and the most effective ones are most selected. it's strange to use the word "predictable" here, since no one claims to understand the chemistry or biology well enough to actually enumerate all possible mutations, and understand their repercussions. mutation+selection is the underlying fact that makes the theory of evolution possible.
Posted by markhahn (32 comments )
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why a surprise?
Is it clear if the word 'predictable' is replaced with 'reproducible'? The surprise to me that one can achieve, in a lab, the sufficient number of generations required to observe reproducible evolution. If results such as these can be simulated in-silico, then generalised/validated models that _predict_ evolution will be sure to follow.
Posted by whs_qwghlm (1 comment )
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what evolution?
traits changing because of environment isnt the same as evolution or mutation.isnt almost all mutation deadly?
Posted by newcreation (118 comments )
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Clean Sweep!
Wrong on both counts! :)
Posted by Mister C (423 comments )
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what evolution?
traits changing because of environment isnt the same as evolution or mutation.isnt almost all mutation deadly?.and evolution hasnt been proven yet.i havent seen any talking monkeys yet
Posted by newcreation (118 comments )
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Good one, by the way, could you show me that clip you must have of the guys sitting on clouds, or the hubble pictures of heaven?

I'm sure there must be at least a dozen examples of miners locating hell by now, what about a few snaps of that too?

I'm sure you have an equally amusing response explaining why geologists, archeolosists, paleontologists and the like keep finding stuff that is several hundred million years older than the Earth? 6000 years old huh.. incredible, by the way how does that explain something that is over 6000 light years away, no doubt light is a subversive theory that hasn't been proved yet.

(A light year for the uneducated, is the a measure of the time that light takes to reach that which is viewing it.. e.g. if something is 1000 light years away, it took the light from that object 1000 years to reach whoever or whatever viewed it, and would take you 1000 years, travelling at the speed of light, to reach it). No
Posted by ajbright (447 comments )
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...moving beyond 4th-grade science.
>> traits changing because of environment isnt the same as evolution or mutation...

...successful new "traits" and behaviors are reinforced by "environment[al]" factors through increased "reproductive-success" within an ecosystem. This is usually referred to as "natural selection".

>> isnt almost all mutation deadly?..

No, "mutation" simply means change. Each time a DNA molecule is replicated, by a complex interaction between the DNA molecule and an RNA molecule, a certain, measurable, percentage of the DNAs genetic-code is inevitably altered from the original sequence. Additionally, external-factors can also cause such "mutations". These "limited base-pair mutations" usually have no effect on the overall organism due to the fact that there is so much information contained within the genome, as well as the fact that the fundamental structure is often both, somewhat redundant, and remarkably "fault-tolerant". However, over time these chemical "mutations" do accumulate, and through the enzymatic process of cell-structure regulation, an organisms macro-structure can be altered, either subtly, or drastically, over generations.

Unsuccessful "changes" tend to be purged by the "environment". And, more successful variants tend to propagate. In fact, the field of "CHAOS mathematics" demonstrates that a simple rule-set can produce the two unique characteristics of such "evolutionary processes".

1. A relative stability within a general macro-structure, while numerous minor code "mutations" accumulate.


2. Rapid, sweeping-shifts toward a new macro-structure (envelope), once a trigger-threshold of "mutations" is reached. This is then often followed by a period of relative homeostasis (stability) within the new "envelope".

>> and evolution hasnt been proven yet.i havent seen any talking monkeys yet

Obviously, these processes, and "Evolution" in general, HAVE BEEN both scientifically proven, and CAN BE "scientifically" demonstrated.

But, if you are still looking for "talking monkeys", ...just look around you, ...PEOPLE ARE EVERYWHERE. But, "...the ability to speak, does not necessarily make one intelligent" - Qui-gon Jinn.
Posted by Raife (63 comments )
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