Celsus

Hi all,

Ok, so this is my first proper foray on this forum. I read Enrst Mayr's What Evolution Is some months ago, and he says selection acts on the phenotype. Quite sensible by the sounds of it. However, an even longer time ago, I remember Dawkins insisting that the gene is the appropriate level of analysis. I think. My question is, is there a conflict or not (or am I just confused)?

Second question is, does any normal people understand what The Extended Phenotype is trying to say? (non-biologists I mean )

Ta,
Joel

pz

Yes, there is a very messy conflict, and biologists argue back and forth on it.

For a measure of how complicated it is, take a look at Gould's magnum opus, The Structure of Evolutionary Theory. In large part, that huge book is all about different perspectives on the levels of evolution.

My personal take on it (which is not definitive, of course) is that there are instances where the idea of selection at the level of the gene is correct and appropriate, but that Dawkins is mainly barking up at one particular twig and missing the rest of the tree.

Celsus

Thanks for the response. Is there any less weighty (and expensive) tomes that a layman like myself might be able to obtain to get their heads around this idea?

Doubting Didymus

Which idea, exactly? Give us more of an Idea of what you need to know, and which perspective you want it from.

Celsus

The opposing views/evidence for phenotype vs. gene. Or are there no biology books dealing with both sides of the issue?

Doubting Didymus

You're approaching the subject slightly off kilter. No biologist will insist on a complete division between phenotype and genes. The controversy is basically over how much emphasis to place on one or the other. Really, as scientific disputes go this is a really insignificant thing, but scientists need something to argue over, and they agree on so much in the evolutionary field that the little things get amplified.

Dawkins' perspective is that the gene constitutes a 'unit' of selection, being (in his veiw) the only thing that satisfies the criteria of heritability, mutability and permenence. Obviously they are not selected directly, but via the phenotype. To expound: AGGTCC may be an improved version of AGGTTC, but selection will not be 'looking' at the base pairs themselves, but the phenotypic effects. The Selfish Gene, but also The Blind Watchmaker both elaborate on this perspective.

The 'other' side of the debate would suggest that there is not a direct enough relationship between genes and the phenotype to make genes viable selection units. They also suggest that other, perhaps more important factors, also satisfy selection criteria, particularly developmental factors. Again, this position will not be to the exclusion of gene selection, but a simple matter of perspective. I do not know what books other than goulds tome will expound to a layman on this idea.

Celsus

Thanks Didymus

Thinking about it, I suppose I'm more interested in Mayr's view, just because it's more intuitive, and I've read plenty of Dawkins explaining his gene's viewpoint. I'm looking for some compromise in the middle, but both authors seem to be insisting on their viewpoint as the correct one, and the other as "invalid". (e.g. ch. 6 in Mayr's What Evolution Is)

Anyway, my first book on evolution was *cough* Evolution: A Theory in Crisis *cough* so I've got some way to go to understanding all this. The thing is, reading pop evolution books has a tendency to leave authorial bias unchecked, and laymen like myself (or maybe it's just myself) have no idea what to do when seemingly diametrically opposed viewpoints are shown in different books (with no dialogue between the two viewpoints), short of reading something like Gould's Structure.

Joel

Amit Misra

Hi Celsus,
As another interested amateur in the field of evolutionary biology, I sympathize with your dilemma. Mayr is the grand old man, after all, and I think his newer book: "This is Biology" is a better take on the subject.
In the 1980s, a bunch of biologists and philosophers got together and had a seminar, the proceedings of which have been published under the title: "Individuals, Populations, Communities: Controversies on the Unit of Selection." Unfortunately, I don't have the publication details, but all the editors had names that began with a "B." Remember, this is the time when V.C. Wynne-Edwards et al were hypothesizing group selection on the basis of roosting behaviour in birds. This book takes in a lot of input and insight from non-biologists. Hope you can find it in a public library.
Cheers
Amit

Albion

Amit, What Evolution Is is Mayr's most recent work. Are you thinking of another book that pre-dates This Is Biology?

The Lone Ranger

In my opinion, perhaps the best book on evolutionary theory for non-biologists is Jonathan Weiner's The Beak of the Finch.

I think that the whole "what is the unit of selection" debate tends to get blown way out of proportion. It seems to me perfectly clear that selection can operate at different levels under different circumstances.

Dawkins makes it clear in such works as The Selfish Gene and The Extended Phenotype that the phenotype determines how successfully an organism reproduces, but it's the genes that either get passed on or don't. This seems to me utterly uncontroversial. There's a great deal more overlap in the views of the opposing camps than either side seems to want to admit.

Dawkins (in my opinion) seems to take an overly narrow view, but it's not nearly as narrow as people like Gould would have us believe. Such is my interpretation, anyway.

Selection can and does work at different levels -- that seems perfectly clear. For example, population biologists have repeatedly shown how interdemic selection can be an important force in the evolution of populations. This isn't exactly group selection, but it sounds an awful lot like it at first. Nevertheless, it happens.

Cheers,

Michael