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Behavior May Influence Evolution
eldavojohn writes "Pending your beliefs about evolution, National Geographic is running an interesting article on the influences of behavior on evolution. The study supports the controversial idea that an animal's behavior in response to environmental change can spur evolutionary adaptations. By adding a predator to an island where a species of lizards lived with no predators, they witnessed a quick shift in the average length of legs on the lizards. Long legs meant to escape were useless against the new larger predators while short legs became the dominant feature since they increased climbing ability (to trees the predators could not reach). For the finer details on the research, visit the Losos Lab Research Page."
The study also supports a somewhat controversial idea in biology: Animals' behavior in response to environmental change can spur evolutionary adaptations.
Could that imply that the behaviour of disbelieving scientific facts could spur a reduction in brain size in order to adapt to reduced intelligence?
"We are all geniuses when we dream"
- E.M. Cioran
It only makes sense. If the "animal" is intelligent to overcome its primal instincts it can avoid "evolutionary" dangers.
Are we not doing seeing this now in humans with antibiotics? Genetic manipulation?
How many people on Slashdot have said that the gene pool has become watered down due to the protections of civilization?
When the environment changes, some animals are better adapted to the new change than others. Details at 11.
'Sensible' is a curse word.
This isn't evolutionary adaptation - it's much more simple than that. If you start killing all of the lizards with long legs, the ones with short legs are going to mate and have offspring with short legs. There is nothing new or "adapted." Also, if the short-legged ones get away and the long-legged ones don't, isn't that going to inherently affect how many have long legs and how many have short, by proportion?
From the article description, I thought this experiment was going to provide evidence for Lamarkism or something. In fact, this seems an interesting, but not too-surprising finding.
Introduce a change to the environment that causes a behavioural change - is it so surprising that some members of the population are better suited to the behaviour than others?
Apropos nothing, it's pretty sad to see such a story headed with the words "Pending your beliefs about evolution" on a site such as Slashdot. Evolution is an observable fact. Evolution through natural selection is a massively successful and well supported theory.
No doubt "behaviour influencing eveloution" will be seized upon by the intelligent design brigade. Though as usual the headline is misleading. Instead of evolution on one axis (e.g. speed) it's on a combination of various abilities (running fast/hiding/climbing/fighting) plus choosing the right strategy. If the rules of the game change, e.g. a faster predator comes along, what you see is what you'd expect - those adapted for running away (as opposed to the hiders, the climbers, the smelly chemical squirters) are now at a disadvantage; they're fighting the previous war. Nothing to see here.
It's true I tell you, feller at work's next door neighbour read it in the paper.
I'm in no shape or form a scientist, but is this really an example of evolution? The long legs vs. short legs reminds of the the hiking boots vs. running shoes joke. I think this is a better example of the I-don't-have-to-outrun-the-bear-just-you school of thought.
Maybe you can argue that it was only natural for them to seek safety in the trees but I think that this study addresses something we must face. If you believe in evolution, you have to acknowledge that it's not only random genetics but also influenced by the behaviors of the animals granted those random mutations. If the lizards had behaved differently and not gone to the trees, perhaps longer and longer legs would have been developed until they were fast enough to outrun their predators. Or perhaps the species just would have been eradicated on the island.
Controversial because it implies that species may be able to subconsciously choose which feature is 'evolved' to be the dominant factor.
If you want to apply this to human evolution (as one is naturally only concerned with their own species), then I suggest you read Guns, Germs & Steel by Jared Diamond. What I found interesting is that in some places, humans began a farming lifestyle earlier than other hunter-gatherers. It was this decision by way of discovery that led some civilizations to outpace others. In fact, the choice or 'discovery' of planting seeds and harvesting them periodically eventually led to some regions invading and 'colonizing' other regions. Can we call this evolution? Can we say that some evolution hinges on behavioral choices? I think we can, but that's why it's controversial because it has traditionally been thought that the dominant feature was only influenced by the environment--not by a choice made by the animal.
My work here is dung.
I've recently been "Studying" evolution in my spare time.
This is a cool experiment, but it's nothing "new" -- there's no new knowledge here. At all.
AND there's NOTHING AT ALL about "behavior may be inherited!" Where did THAT come from -- anyone?(*) All these lizards were already prone to running up trees. The ones with shorter legs did it better, and within just a few generations the average legs length of the population was shorter.
That's *basic* evolution, people. Go read a damn book!!! The submitter of this article makes me angry because I realize now the fight for education about Evolution isn't just for stupid fundamentalists. A lot of smart people don't get it either.
I highly recommend getting yourself a copy of "The Selfish Gene" by Richard Dawkins. Read all the chapter notes, too -- get the recent version, don't gt an original copy because it makes you cool. Dawkins commentary on what he wrote in the newer printings is invaluable. It's an excellent book, and it's FUN to read... seriously!
(* I mean, in this context. It's well-known that behavior is inherited -- but not learned behavior.)
I read awhile back about comparing possum on an isolated island showed a much stronger genetic base that produced better litters and eventual adults versus those who lived on the mainland.
Apparently the stress put on possums on the mainland is high enough to cause genetic changes. the stress weakens the immune system and has other side effects that produced a less healthy and capable possum. One possibility that was raised is that on the mainland a good number of possum are killed by vehicles. Cars are obviously a predator that mainland possum can adapt to, or maybe there hasn't been enough time yet?
I wish I could find the exact story but all I end up with are references to NZ based studies.
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* Winners compare their achievements to their goals, losers compare theirs to that of others.
To clarify:
A good example of phentotypic plasticity is found in ants. The different castes of ants in a hill are very different, such as workers and guards. This difference isn't found in their genes. Their genomes contain the molds for all the variations.
The eggs are treated differently, and this results in vastly different creatures coming out of the egg.
This is what the study suggests is happening, to a lesser degree, in the lizards.
The National Geographic article is wildly inaccurate.
I'm a dreamer, the world is my playpen. But hey, I'm a serious person, I can't dream all the time.
The author of the article has wildly misunderstood the study.
What the study is saying is: "This suggests that the results observed in the field may be the result of a phenotypic plasticity in limb growth, rather than genetic differentiation."
Phenotypic plasticity is something we find amongst other thing in ants.
The various castes of ants (workers, warriors, etc) differ from eachother quite a bit. However, their genes are the same - Their genome holds the molds for all their various forms. Through different treatment of the eggs by the queen and the workers, different parts of the genome is activated.
So the study is suggesting that these lizards have evolved this ability: To, through some mechanism still unknown, influence the leg length of their children to pick between at least two different phenotypes. One with short legs, one with longer ones.
Interesting? Sure. Changing "Evolution's Driving Force"? Definitively not.
Someone needs to introduce the author of the article to an anthill. It would blow him away.
I'm a dreamer, the world is my playpen. But hey, I'm a serious person, I can't dream all the time.
I'm hijacking a higher thread since pretty much everything written below is just plain wrong.
Not the submitters' fault, they simply read the article and based what they wrote on it.
Let me explain:
The article is claiming that "Evolution's Driving Force Shifts Based on Behavior"
Go to the actual research site (linked in submission), scroll down to the end, and you will find that what they're saying is:
"... another alternative is that lizards growing in different environments grow different length legs. To test this hypothesis, we raised baby anoles on two different surfaces at the St. Louis Zoo--either on 2x4's or on narrow (1/4") dowels. At the end of three months, the lizards raised on broader surfaces had longer limbs than the lizards on narrower surfaces! This suggests that the results observed in the field may be the result of a phenotypic plasticity in limb growth, rather than genetic differentiation."
Phenotypic plasticity is a term some of you may be unfamiliar with, a good example of it is found in ants.
In any given hill, there are different castes of ants. Warriors, workers, etc. They are all quite different.
However, the differences are not genetic; they arise during development and depend on the manner of treatment of the eggs by the queen and the workers, who manipulate such factors as embryonic diet and incubation temperature. The genome of each individual contains all the instructions needed to develop into any one of several 'morphs', but only the genes that form part of one developmental program are activated.
This is what the study suggests is happening to these lizards.
They're saying there are at least two different 'morphs', one with long legs and one with short ones, in the genome of the lizards.
These are then selected between (through some so far unknown mechanism) based on the environment of the lizards.
"These findings suggest the intriguing possibility that phenotypic plasticity may play an important role in adaptive differentiation by permitting lizards to occupy different habitats; once subsequent mutations arise, these differences can then be elaborated upon by natural selection."
Now, let the ghosts of Lamarckism the article has raised from their graves go to rest.
I'm a dreamer, the world is my playpen. But hey, I'm a serious person, I can't dream all the time.
You may be overly trusting in the article writer. The writer may have deliberately misinterpreted the article so as to create a controversy, base on the study's title. The idea that behavior doesn't influence evolution would actually be a whole lot more controversial among people who understand the subject. You could post exactly the same information, put a headline to the effect that it supports 'intelligent design theory,' and watch the outraged comments pile up! What fun!
Long legs meant to escape were useless against the new larger predators while short legs became the dominant feature since they increased climbing ability (to trees the predators could not reach).
This could simply be the animals with long legs being eaten at a more frequent rate, so the short legged lizards are the ones surviving and reproducing. This is, at best, micro-evolution. Their genetic makeup isn't changing to accomidate the need for short legs (like evolution would *know* that it needed short legs). Its selective breeding.
-- If we don't stand up for our rights, now, there will be no right to stand up for them later.