Scientists reveal driving force behind evolution

Feb 25, 2010

Scientists at the University of Liverpool have provided the first experimental evidence that shows that evolution is driven most powerfully by interactions between species, rather than adaptation to the environment.

The team observed viruses as they evolved over hundreds of generations to infect bacteria. They found that when the bacteria could evolve defences, the viruses evolved at a quicker rate and generated greater diversity, compared to situations where the bacteria were unable to adapt to the viral infection.

The study shows, for the first time, that the American Leigh Van Valen was correct in his 'Red Queen Hypothesis'. The theory, first put forward in the 1970s, was named after a passage in Lewis Carroll's Through the Looking Glass in which the Red Queen tells Alice, 'It takes all the running you can do to keep in the same place'. This suggested that species were in a constant race for survival and have to continue to evolve new ways of defending themselves throughout time.

Dr Steve Paterson, from the University's School of Biosciences, explains: "Historically, it was assumed that most was driven by a need to adapt to the environment or habitat. The Red Queen Hypothesis challenged this by pointing out that actually most will arise from co-evolutionary interactions with other species, not from interactions with the environment.

"This suggested that was created by 'tit-for-tat' adaptations by species in constant combat. This theory is widely accepted in the science community, but this is the first time we have been able to show evidence of it in an experiment with living things."

Dr Michael Brockhurst said: "We used fast-evolving viruses so that we could observe hundreds of generations of evolution. We found that for every viral strategy of attack, the bacteria would adapt to defend itself, which triggered an endless cycle of co-evolutionary change. We compared this with evolution against a fixed target, by disabling the bacteria's ability to adapt to the virus.

"These experiments showed us that co-evolutionary interactions between species result in more genetically diverse populations, compared to instances where the host was not able to adapt to the parasite. The virus was also able to evolve twice as quickly when the were allowed to evolve alongside it."

The team used high-throughput DNA sequencing technology at the Centre for Genomic Research to sequence thousands of virus genomes. The next stage of the research is to understand how co-evolution differs when interacting species help, rather than harm, one another.

The research is published in journal Nature.

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User comments : 21

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fourthrocker
5 / 5 (8) Feb 25, 2010
I thought interaction between species IS adapting and interacting with their environment.
CyberRat
1 / 5 (1) Feb 25, 2010
Jees, they just made animalsex illegal in the Netherlands.
jamey
4.8 / 5 (4) Feb 25, 2010
I have to agree with fourthrocker - I thought other species *WERE* part of the environment!
SincerelyTwo
not rated yet Feb 25, 2010
Seriously? I always assumed that interaction between species was a part of the environment ... I could swear the books I've read even implied it. Huh.

Is science some how dumbing itself down? Was it seriously not 'formally' understood that interaction between species was a driving force in evolution before now?

This can't be...
marjon
1 / 5 (1) Feb 25, 2010
interactions between species, rather than adaptation to the environment.


Interactions between species is part of the environment, no?

Yellowdart
not rated yet Feb 25, 2010
Rigging the experiment in the first place.

Youve taken away the bacteria's response to its environment when you disabled it yourself. Its not an interaction if you disabled the interaction...

What you should measure, is any change in the bacteria's rate of evolution when subjected to viruses vs. some other environmental change.

seneca
1 / 5 (1) Feb 25, 2010
It's well known, the richness of speciation is driven by predation competition, for example: predators adapt to specific prey, which evades specialized predators by changing its habits and/or physiognomy and so on..

This model explains well the seemingly redundant number of invertebrate species especially at coral reefs and rain-forests rich of food supplies, where life environment is relatively stable - so no particular reason for evolution exists here.
KB6
not rated yet Feb 25, 2010
Yellowdart, they disabled one population of bacteria to create a control group so that no one would be able to argue that the viruses may have mutated and evolved anyway, regardless of the bacteria's ability to adapt.
Skeptic_Heretic
not rated yet Feb 25, 2010
Here's the real driver of evolution: Food.

Natural development of more efficient means by which to collect energy for use is what you can define evolution as for all things animate and inanimate.
Yellowdart
not rated yet Feb 25, 2010
Ah, my apologies, it was a viral comparison. Is a viral comparison solely against disabled bacteria definative of the rest of the animal kingdom tho, when viruses arent your typical "lifeform"?

You didnt alter any other aspect of the viruses environment. Is it always faster under more stress, or is it solely under it's preys ability to respond?

And is it really that substantial when its only twice as fast, for already fast evolving viruses?

KB6
not rated yet Feb 25, 2010
I don't know how valid it is to extrapolate evolution of viruses to other organisms either because, as you pointed out, they aren't at all "typical." The viruses are probably mutating at a more or less constant rate regardless of what the bacteria are doing. It's just that the adapting bacteria are selecting for viruses that can keep up with the bacteria's evolving defenses, so changing the genetics of the whole viral population. So the process is proceeding in a way very similar to how most species evolve. Evolving "twice as fast" is quite fast enough when comparing two populations of the same progenitor species. I'm not sure, but I'd bet that in populations of real world, eukaryotic species the rate of retained mutations usually isn't that high. And the changes are cumulative.
stealthc
1 / 5 (1) Feb 25, 2010
This comment seems a little retarded, I think both of equally driving factors and not one or the other. That would make more sense considering the environment drove the evolution of bugs to be smaller over time as oxygen levels in the atmosphere decreased; and that has nothing to do with interaction between species and more to do with the environment, and it would seem it played a pretty large role in the evolution of all bugs on earth. More junk science at it's finest.
Caliban
1 / 5 (1) Feb 26, 2010
Here's the real driver of evolution: Food.

Natural development of more efficient means by which to collect energy for use is what you can define evolution as for all things animate and inanimate.

skeptic,
viruses don't consume the host they invade- they kill them by redirecting the host's metabolism to replicating copies of themselves. Just to keep it specific to the study at hand.
Otherwise, competition for food is, indeed, one of the many drivers of evolution. As is most certainly interspecies competition. Other than individual variability(after the variation arises) there really isn't any evolutionary factor that isn't_ environmental.
This study is just what the rest of you have said- as worded, a complete joke, and not even worth using to wipe one's backside with.
I am curious as to how this clown ever got funding for this research, based on that hypothesis.
joco
not rated yet Feb 26, 2010
Of course other species are a part of environment.
Bacterias are practically the only environment that bacteriophags have.
This "experimental evidence" or the conclusions are a big obvious fail.
breadhead
1 / 5 (4) Feb 26, 2010
Let's see, the word "evolution" was used many times in this article, but what they are seeing is variation in a kind. So, was the result of the virus changing, still a virus perhaps? Or did it grow legs and walk away? Perhaps it grew a mouth and spoke to these guys.
Skeptic_Heretic
not rated yet Feb 27, 2010
skeptic,
viruses don't consume the host they invade- they kill them by redirecting the host's metabolism to replicating copies of themselves. Just to keep it specific to the study at hand.

And your point? Viruses do consume the host. The infect the cell, replace pieces of DNA and the cell is then consumed in creating copies of the virus.

I'm well aware that virii do not have mouths, nor do they "eat" however the term "food" when replaced with a more relevant term, like energy, shows the accuracy of my statement.
Ethelred
not rated yet Mar 01, 2010
Caliban said:
This study is just what the rest of you have said- as worded, a complete joke, and not even worth using to wipe one's backside with.


The article is NOT the study. Don't mistake the usual crappy reporting and hyperbolic comments for a bad study.

As a study of the Red Queens Race this study looks solid. It might even be the first time where the stress that drove evolution in a lab experiment came co-evolving predators instead of chemical stress. To do that sort of experiment the environment, NOT INCLUDING THE PREDATORS, must be controlled and kept the same. Thus, in this experiment, the environment, NOT INCLUDING THE PREDATORS, did not contribute to the evolution of the bacteria.

Yes it would be nice if the language used wasn't fuzzy. But that does not invalidate the experiment.

And yes viruses are predators even though they do not have teeth or consciousness.

Ethelred
breadhead
1 / 5 (1) Mar 07, 2010
Since the person leading the team is called an "evolutionary biologist", the study begins with a fatal flaw. I can pretty much throw away the rest of the article.

If there was such a race for survival, how did they ever start in the first place? If the co-evolutionary interaction required both critters
to be there, did they come in to existance at the same time? How did this mechanism work prior to both existing?

How do you know anything evolved here? How do you know that the various adaptations (As called here) didn't already exist in the genetic code for that critter?

What a poor excuse to use the word, "evolution" over and over.
johnsopinion
not rated yet Mar 08, 2010
I would like to know more about what 'allowed' the evolution of the defences and what prevented "the bacteria...to adapt to the viral infection."
Isn't that kinda important?
Ethelred
5 / 5 (1) Mar 10, 2010
If the co-evolutionary interaction required both critters to be there, did they come in to existance at the same time?
Simple. first they both existed and then they started to interact, thus started up the Red Queen's Race.

Its so obvious I suspect that you didn't really want an answer.
How did this mechanism work prior to both existing?
Obviously it didn't exist until they both existed IN THE SAME PLACE. Prior to that they could both exist in different places where they would have been to adapting to the previously existing environment.
How do you know anything evolved here?
and{How do you know that the various adaptations
As called here) didn't already exist in the genetic code for that critter?
They checked the DNA. Before and after. Again it looks like simply don't want to think about it.
What a poor excuse to use the word, "evolution" over and over.
Articles about evolution tend use the word. What is your REAL problem with it?

Ethelred
ERMeyer
5 / 5 (2) Mar 11, 2010
It is astounding that anyone would claim that an experiment with two or more species would invalidate Darwin's theory of evolution. Read his work. If you look at his first paper (1858) to propose evolution through natural selection, by the second page he outlines clearly how coevolution could occur in predator-prey interactions.. His example was canids such as foxes or dogs, and prey such as rabbits or hares. Again if you look at his later work, he proposes two-species intereractions between flowers and moths, and proposes how change in one drives change in the other. At the same time, he recognized that changes in the physical environment can also drive evolution. Most college texts summarize his work in ways that make it less interesting, instead of getting students to actually read his work. That first short paper of 1858, and Wallace's are remarkable.

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