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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."
My work here is dung.
I'd recommend the following books over Dawkins':
Mary Jane West-Eberhard's Developmental Plasticity and Evolution
Jablonka & Lamb's Evolution in Four Dimensions: Genetic, Epigenetic, Behavioral, and Symbolic Variation in the History of Life
Both books show quite well how the modern synthesis is changing and what is likely to incorporated into it. The former book is particularly revolutionizing, the latter is every bit as readable as Dawkins is for the layperson. Both books benefit from the wealth of insights from molecular genetics and other areas pertaining to evolutionary theory within the last 20 years, unlike The Selfish Gene.
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.
The whole article in National Geographic is terrible. It doesn't say anywhere what sort of evolution they're talking about.
It does say "Losos and his colleagues' work reported only on changes in the anoles over a single generation". Let's say Stalin kills off all intellectuals in Russia, so that the only Russians left alive are non-intellectuals. Would this provide evidence for evolution in Russian society? Of course not! To see evolution, you need to see multiple generations of the thing that's evolving.
When most people talk about evolution, they mean genetic evolution, i.e. over the course of several generations the gene pool adapts in favour of genes which confer survival benefits. This is a single-generation study, and we don't even know whether leg length in these lizards is defined by their genes or by their early experiences (e.g. all lizards might have the same genes, but sporty well-fed lizards may end up with longer legs), so there's no way it provides evidence for evolution.
Dawkins had the idea that memes (transmittable behavioural traits) can evolve too. He gave the example of "hawk behaviour" and "dove behaviour", and described how the prevalences of these behaviours might change in an evolutionary way. I suppose it's possible that there's evolution going on at the meme level here, but I doubt very much that an adult lizard's leg length can change very much during its lifetime, so I don't see how meme evolution might come into this study.
So all we're left with is an experiment that looks at selection pressures, not evolution. As the article quotes: "the experimental approach--unusual in most evolutionary studies in the wild--is what allowed the researchers to detect the sharp, sudden swings in natural selection."
But the follow-on is a complete non-sequitur: "This demonstrates that evolutionary biology can be a predictive, experimental science like any other".
I think that journalism/science like this just gives evolutionary science a bad name. If you do a study on selection within a single generation, and then say it gives evidence for evolution, it's bad science, and it invites attack on evolution as a whole.