timtyler comments on Group selection update - Less Wrong

38 Post author: PhilGoetz 01 November 2010 04:51PM

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Comment author: timtyler 02 November 2010 09:53:56AM *  3 points [-]

Wikipedia gives an acceptable definition:

In evolutionary biology, group selection refers to the idea that alleles can become fixed or spread in a population because of the benefits they bestow on groups, regardless of the alleles' effect on the fitness of individuals within that group.

In the context of biology or ecology, a "population" is defined as being a collection of organisms of the same species:

A population is all the organisms that both belong to the same species and live in the same geographical area.

Population: In biology and ecology, a group of organisms of one species, living in a certain area. The organisms are able to interbreed. It also refers to the members of a given species in a community of living things.

population: a group of organisms of the same species inhabiting a given area

For examples of group selection critics being more sympathetic towards species selection, see Dawkins, T.E.P., page 101 onwards and Mark Ridley's evolution textbook:

For a different definition, consider:

Group selection is said to occur when the traits of groups that systematically out-reproduce competing groups eventually come to characterize the species.

Comment author: timtyler 02 November 2010 09:46:29PM *  2 points [-]

That wasn't my greatest reply ever - I was in a rush. Yes, Dawkins included species in your quote. And Williams (1966) defined the term "group" in a way that didn't explicitly rule out species. So, I agree that some prominent folks have included species under the group selection umbrella at least once.

However, at least 90% of group selection models deal with sexual species. If you claim group selection exists, and then exhibit species selection to prove it, an awful lot of evolutionary biologists are going to say: "well, that's just species selection - we already know about that".

Interdemic selection has a problem not found in species selection - namely gene flow typically tends to quickly destroy variation between groups. It is that that effect that Maynard-Smith modelled in the material you cite - and it is interdemic selection which is the most controversial.

Comment author: PhilGoetz 02 November 2010 08:07:12PM 2 points [-]

In the context of biology or ecology, a "population" is defined as being a collection of organisms of the same species

A species is a collection of organisms of the same species.

Comment author: wedrifid 02 November 2010 08:21:37PM 3 points [-]

A family is a collection of organisms of the same species (although I have my doubts about that aunt...)

Your point is not clear to me.

Comment author: timtyler 02 November 2010 09:10:06PM 1 point [-]

If you define a species as the set of all such organisms, then a "population" is a subset of that set.

Comment author: PhilGoetz 03 November 2010 02:56:25AM 1 point [-]

And a set is a subset of itself.

Comment author: timtyler 03 November 2010 06:56:19AM 2 points [-]

I don't really see where you are going with this. Yes, all the members of a species could qualify as being a "population" - expecially if they all lived in the same place.

However, that doesn't make species selection into a special case of group selection under the Wikipedia definition.

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