The cited article is about species selection—but this post claims to be about group selection.
As biologists often use the terms, group selection and species selection are quite different concepts.
The standard objection to group selection—which is that gene transfer due to between-group migration and recombination usually swamps the effect of between-group selection—doesn’t apply to selection between species—because there is little or no gene transfer between species.
As a result, species selection isn’t very controversial—compared to group selection.
Group selection has been demonstrated in the lab (Wade’s flour beetles, etc) - but there is still some controversy over its significance in nature.
Yes, species are groups—but the actual area where there is a controversy is over selection between groups that are within sexual species. Selection between species is not relevant to this.
However, I agree that articles like this make EY look as though he has wandered into an unfamiliar area—which he doesn’t know as much about as he thinks he does.
I’ve just spent 2 hours sorting through various references to group selection to try to figure out whether your distinction is correct. As Samir Okasha writes, “The group selection debate has been characterised by perennial disagreements over concepts and terminology, as well as empirical fact.”
Group selection: A type of natural selection which acts upon whole groups rather than on individuals. Group selection includes interdemic selection (acts on populations within a species) and species selection (acts on species within a higher taxon).
(Gould uses the term interdemic selection, but says it is synonymous with group selection, and distinguishes it from species selection.)
Eliezer’s post talked about species selection. David Wilson’s 2009 blog series on group selection, Truth & Reconciliation (linked to in the post), says nothing about any distinction between “group selection” and “species selection”; and the endangered bird species example of group selection in part 18 (p. 39) is species selection. Read the Wikipedia entry on group selection—everything that it says applies to species selection. All of the arguments presented against group selection apply equally to species selection. Some of the instances of group selection it provides are species selection. It never draws any distinction between group selection and species selection.
Many examples in various sources of group selection do not have between-group migration, and do have extinction of groups. For example, the ant colonies that EO Wilson talks about—there is AFAIK no gene transfer between ant colonies, since ants can’t migrate from one colony to another. On the Wikipedia page on group selection, it includes as examples viruses in rabbits, where selection occurs at the level of a single rabbit, and no gene transfer occurs between different infected rabbits.The Rauch et al analysis referred to is a similar case. So is the “brain worm” example.
Many attacks on group selection, including Williams’ Adaptation and Natural Selection (1966), speak in general terms about selection at higher levels indiscriminately, not singling out group vs. species selection. Here is what Richard Dawkins writes when attacking group selection in The Selfish Gene:
[A] group, such as a species or a population within a species, whose individual members are prepared to sacrifice themselves for the welfare of the group, may be less likely to go extinct than a rival group whose individual members place their own selfish interests first. Therefore the world becomes populated mainly by groups consisting of self-sacrificing individuals. This is the theory of ‘group selection’, long assumed to be true by biologists.
Thus in a 1976 review of the subject, [JMSmith] argued that group selection ‘’requires that groups be able to ‘‘reproduce’’, by splitting or by sending out propagules, and that groups should go extinct’’ (1976, p. 282). The process envisaged by Wynne-Edwards, in which reproductively isolated demes give rise to other such demes, satisfies these conditions, Maynard Smith argued, as does the process of species selection as described by Gould and Eldredge, in which speciation plays the role of demic reproduction.”
So, George Williams, John Maynard Smith, Richard Dawkins, and David Wilson all agree that group selection includes species selection.
Maynard Smith’s haystack model, which was the original theoretical basis for rejecting group selection (and is fatally flawed; see p. 17 of the David Wilson T&R essay), does not work on species selection. The mathematical model that Eliezer used does not apply to species selection (nor to interdemic selection in general). Yet they use the phrase “group selection”. So there is some basis for considering group selection to be synonymous with interdemic selection; but that basis appears to be the carelessness of earlier theorists.
The group-selection-bashing I’ve witnessed for decades has always taken the line that all group selection, including species selection, is equally bad. I’ve seen many people object to the invocation of group selection, and I’ve never noticed any of them draw a distinction between interdemic and species selection.
Please cite a reference for your usage of the terms.
Richard Dawkins wrote an obituary for George Williams in the Oct. 1 Science, in which he said that Williams developed the idea of “clade selection” which Dawkins calls important. Clade selection is the idea that selection can operate on an entire clade.
The article this post is about a clade. It’s clade selection in that the entire clade has benefitted from SI. Is it also species selection, because entire species are selected against when they develop SC? I think so.
In either case, I think it’s hypocritical of Dawkins to call group selection “loose, intellectually shoddy.. muddled”, and in the same article praise clade selection.
Rather than calling Dawkins a hypocrite, don’t you think it would be more appropriate to simply note that Dawkins seems to be another person who doesn’t agree with you that clade selection (and hence species selection) is just one form of group selection?
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.
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.
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:
Group selection is said to occur when the traits of groups that systematically
out-reproduce competing groups eventually come to characterize the species.
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.
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.
As a result, species selection isn’t very controversial—compared to group selection.
Wikipedia seems to contradict this: “It remains controversial among biologists whether selection can operate at and above the level of species.”
I did a quick search on Google and found a paper from 2010 which claims that “Species selection as a potential driver of macroevolutionary trends has been relegated to a largely philosophical position in modern evolutionary biology.”
I’m not very familiar with biology, but at a glance it looks like species selection is pretty controversial.
“It remains controversial among biologists whether selection can operate at and above the level of species.”
That seems to be a rather confused way of putting it. Or course selection operates between species. The issue is whether it results in very much in the way of species-level adaptations.
I did a quick search on Google and found a paper from 2010 which claims that “Species selection as a potential driver of macroevolutionary trends has been relegated to a largely philosophical position in modern evolutionary biology.”
Did you read the whole abstract? They say “species selection is an important process”:
Species selection as a potential driver of macroevolutionary trends has been relegated to a largely philosophical position in modern evolutionary biology. Fundamentally, species selection is the outcome of heritable differences in speciation and extinction rates among lineages when the causal basis of those rate differences can be decoupled from genotypic (within-population) fitnesses. Here, we discuss the rapidly growing literature on variation in species diversification rates as inferred from molecular phylogenies. We argue that modern studies of diversification rates demonstrate that species selection is an important process influencing both the evolution of biological diversity and distributions of phenotypic traits within higher taxa. Explicit recognition of multi-level selection refocuses our attention on the mechanisms by which traits influence speciation and extinction rates.
I did read the whole abstract: the author admits that species selection is controversial in modern evolutionary biology, and in the rest of the paper argues that this should not be the case. The point of my previous comment was not whether species selection should or should not be recognized as important, because I do not know. It was a question concerning how well-accepted species selection is amongst biologists.
That may be so. If so, I am misusing the terminology. But if so, other people routinely use the objection to what you are calling “group selection” to rebut invocations of what you are calling “species selection”.
Hmm—I am not sure I have encountered that. Many definitions of “species” are based on there being little or no gene flow between different species.
Both group selection and species selection face the issue of the fact that reproduction rates are slow—compared to individual reproduction rates—so individual level selection could eliminate much of the variation on which higher-level selection could act.
However, with species selection, we know that species do eventually diverge—so there is some variation left to work on.
With group selection there’s less evidence of divergence between groups—and there’s an additional problem—that occasional gene flow between groups acts to reduce between-group differences. The math[*] suggests around 1 migrant per-generation is enough to make most group selection pretty ineffective—and 1 migrant per-generation is low for most natural groups. These factors are mainly what makes group selection more controversial.
Search for “One-Migrant-per-Generation Rule” for more on this.
The cited article is about species selection—but this post claims to be about group selection.
As biologists often use the terms, group selection and species selection are quite different concepts.
The standard objection to group selection—which is that gene transfer due to between-group migration and recombination usually swamps the effect of between-group selection—doesn’t apply to selection between species—because there is little or no gene transfer between species.
As a result, species selection isn’t very controversial—compared to group selection.
Group selection has been demonstrated in the lab (Wade’s flour beetles, etc) - but there is still some controversy over its significance in nature.
Yes, species are groups—but the actual area where there is a controversy is over selection between groups that are within sexual species. Selection between species is not relevant to this.
However, I agree that articles like this make EY look as though he has wandered into an unfamiliar area—which he doesn’t know as much about as he thinks he does.
I’ve just spent 2 hours sorting through various references to group selection to try to figure out whether your distinction is correct. As Samir Okasha writes, “The group selection debate has been characterised by perennial disagreements over concepts and terminology, as well as empirical fact.”
So far, Stephen J. Gould uses this group/species distinction, and almost everyone else rejects it. The more common usage is given in the BioTech Life Science Dictionary:
(Gould uses the term interdemic selection, but says it is synonymous with group selection, and distinguishes it from species selection.)
Eliezer’s post talked about species selection. David Wilson’s 2009 blog series on group selection, Truth & Reconciliation (linked to in the post), says nothing about any distinction between “group selection” and “species selection”; and the endangered bird species example of group selection in part 18 (p. 39) is species selection. Read the Wikipedia entry on group selection—everything that it says applies to species selection. All of the arguments presented against group selection apply equally to species selection. Some of the instances of group selection it provides are species selection. It never draws any distinction between group selection and species selection.
Many examples in various sources of group selection do not have between-group migration, and do have extinction of groups. For example, the ant colonies that EO Wilson talks about—there is AFAIK no gene transfer between ant colonies, since ants can’t migrate from one colony to another. On the Wikipedia page on group selection, it includes as examples viruses in rabbits, where selection occurs at the level of a single rabbit, and no gene transfer occurs between different infected rabbits.The Rauch et al analysis referred to is a similar case. So is the “brain worm” example.
Many attacks on group selection, including Williams’ Adaptation and Natural Selection (1966), speak in general terms about selection at higher levels indiscriminately, not singling out group vs. species selection. Here is what Richard Dawkins writes when attacking group selection in The Selfish Gene:
Here is a quote from Samir Okasha (2005), Maynard Smith on the levels of selection question:
So, George Williams, John Maynard Smith, Richard Dawkins, and David Wilson all agree that group selection includes species selection.
Maynard Smith’s haystack model, which was the original theoretical basis for rejecting group selection (and is fatally flawed; see p. 17 of the David Wilson T&R essay), does not work on species selection. The mathematical model that Eliezer used does not apply to species selection (nor to interdemic selection in general). Yet they use the phrase “group selection”. So there is some basis for considering group selection to be synonymous with interdemic selection; but that basis appears to be the carelessness of earlier theorists.
The group-selection-bashing I’ve witnessed for decades has always taken the line that all group selection, including species selection, is equally bad. I’ve seen many people object to the invocation of group selection, and I’ve never noticed any of them draw a distinction between interdemic and species selection.
Please cite a reference for your usage of the terms.
Richard Dawkins wrote an obituary for George Williams in the Oct. 1 Science, in which he said that Williams developed the idea of “clade selection” which Dawkins calls important. Clade selection is the idea that selection can operate on an entire clade.
The article this post is about a clade. It’s clade selection in that the entire clade has benefitted from SI. Is it also species selection, because entire species are selected against when they develop SC? I think so.
In either case, I think it’s hypocritical of Dawkins to call group selection “loose, intellectually shoddy.. muddled”, and in the same article praise clade selection.
Rather than calling Dawkins a hypocrite, don’t you think it would be more appropriate to simply note that Dawkins seems to be another person who doesn’t agree with you that clade selection (and hence species selection) is just one form of group selection?
Obituary: George C. Williams (1926–2010) - By RICHARD DAWKINS
Wikipedia gives an acceptable definition:
http://en.wikipedia.org/wiki/Group_selection
In the context of biology or ecology, a “population” is defined as being a collection of organisms of the same species:
http://en.wikipedia.org/wiki/Population
http://www.talktalk.co.uk/reference/encyclopaedia/hutchinson/m0015159.html
http://wordnetweb.princeton.edu/perl/webwn?s=population
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:
http://www.blackwellpublishing.com/ridley/a-z/Group_selection_.asp
http://www.blackwellpublishing.com/ridley/a-z/Species_selection.asp
For a different definition, consider:
http://www.clarku.edu/faculty/nthompson/Publish%20Work/meta4grp.pdf
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.
A species is a collection of organisms of the same species.
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.
If you define a species as the set of all such organisms, then a “population” is a subset of that set.
And a set is a subset of itself.
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.
Wikipedia seems to contradict this: “It remains controversial among biologists whether selection can operate at and above the level of species.”
I did a quick search on Google and found a paper from 2010 which claims that “Species selection as a potential driver of macroevolutionary trends has been relegated to a largely philosophical position in modern evolutionary biology.”
I’m not very familiar with biology, but at a glance it looks like species selection is pretty controversial.
That seems to be a rather confused way of putting it. Or course selection operates between species. The issue is whether it results in very much in the way of species-level adaptations.
Did you read the whole abstract? They say “species selection is an important process”:
I did read the whole abstract: the author admits that species selection is controversial in modern evolutionary biology, and in the rest of the paper argues that this should not be the case. The point of my previous comment was not whether species selection should or should not be recognized as important, because I do not know. It was a question concerning how well-accepted species selection is amongst biologists.
That may be so. If so, I am misusing the terminology. But if so, other people routinely use the objection to what you are calling “group selection” to rebut invocations of what you are calling “species selection”.
Hmm—I am not sure I have encountered that. Many definitions of “species” are based on there being little or no gene flow between different species.
Both group selection and species selection face the issue of the fact that reproduction rates are slow—compared to individual reproduction rates—so individual level selection could eliminate much of the variation on which higher-level selection could act.
However, with species selection, we know that species do eventually diverge—so there is some variation left to work on.
With group selection there’s less evidence of divergence between groups—and there’s an additional problem—that occasional gene flow between groups acts to reduce between-group differences. The math[*] suggests around 1 migrant per-generation is enough to make most group selection pretty ineffective—and 1 migrant per-generation is low for most natural groups. These factors are mainly what makes group selection more controversial.
Search for “One-Migrant-per-Generation Rule” for more on this.