Group selection update

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.

Tribal groups today have terrible land and strange circumstances. It's my impression that tribal groups found by European explorers very frequently had strong altruism internally.

From what I understand, speciation takes much, much longer than normal mutation. Wouldn't that mean that species selection happens much slower, and by extension with much less effect. Do flowers speciate really fast? Does the more significant difference between the species allow it to evolve faster enough to make up for it?

I think that everyone sensible agrees that group selection happens within an ontology with the categories 'individual selection' and 'group selection'. The question is whether it's ever useful from the perspective of an ontology with the category 'gene's eye view selection' and whether, in the earlier ontology, it's a good idea to set priors strongly against group selection being needed to explain any individual phenomenon.

The data shows that sC > sI, but eC >> eI, enough so that rI < rC + qIC.

This should be "rI > rC + qIC", otherwise SI would have gone extinct instead of there being a positive equilibrium level.

I'm not sure from your essay what you mean by group selection at all.

Group selection, as I've heard it explained before, is the idea that genes spread because their effects are for the good of the group, or species. The whole point of evolution is that genes do well because of what they do for the survival of the gene. The effect isn't on the group, or on the individual, the species, or any other unit other than the unit that gets copied and inherited.

The question that seems obvious is how self-incompatibility ever evolved in the first place, It must have arisen in a species that was self-compatible, and then gradually have risen to fixation in that species. The opposite can happen.

Let's look at this from the point of view of a gene. Suppose a particular mutation in a single gene results in self-compatibility. What's the story for the gene? Let's suppose that it gives an overwhelming advantage over outside genes in fertilising itself, plus a normal chance at fertilising others. That gene ought to do well.

Well, maybe. If the plant has a typical set of recessive genes in its genome, self-fertilisation is a disaster. A few generations down the line, the self-fertilising plant will have plenty of genetic problems arising from recessive gene problems, and will probably die out. This means that self-fertilisation is bad - a gene for self-fertilisation will only prosper in those cases where it's not fertilising itself.

So let's change the scenario and assume the self-fertiliser manages to create a clone instead. Now many plants actually do cloning - it's not inherently a bad idea. But even a good clone is not as good as a gene pool. Your neighbouring plants further up the hill might have specific adaptations to the soil up there that yours doesn't have. The self-cloning plant can't live there. Further south, where the climate is different - your clone won't grow there. It will not spread throughout a whole range of environments as well as a species with an established gene pool can.

The general theme of clones is that they do very well for a while. But they can't spread outside their original environment because they can't reshuffle genes from the general gene pool. Then some disease springs up. Either it kills none of the clones, or essentially all of them. The regular gene pool suffers some losses, but has some survivors too.

Flowering is optional, but survival is compulsory. When times are hard, you put off sexual reproduction until later, and do just as well as any clone ever could. In really tough times, the variations in the sexual plants may prove to be the difference (for some of them) between survival and death, whilst all the clones end up perishing.

So many plants do a bit of both. They clone themselves when the going is good. Then they reproduce sexually after a while, when the benefits of rearrangement outweigh the costs of all the pollen, flowers etc. There are benefits, otherwise they wouldn't bother.

Human history is full of group selection n. Every time one group with better technology or social organization pushes another group off of its land, that's at least group selection n.

It might make more sense to think of one technology or one form of social organization pushing others out of existence. Human beings (and the rest of the environment) could be thought of as the resources used for propagation.

In this context group selection seems like an obviously important idea for understanding certain salient phenomena.

The groups never go extinct. But group selection happens when groups are selected against. The math used to argue against group selection assumes from the outset that group selection does not occur. (This is also true of Maynard Smith's famous haystack model.)

That argument is invalid. Adaptations arise as a result of differential reproductive success. Some haystacks do indeed do better than others in contributing to future haystacks - since they contain more individuals which contribute to the big pool of individuals, from which the next generation of haystacks is produced. So: Maynard Smith's model is just fine in this respect.

The Harpending and Rogers model from 1987 that you critique works in the same way.

Selection does not require different rates of extinction if there are different levels of reproductive sucecss.

The red queen hypothesis for sex (which is pretty close to the paper you cite) has always seemed to me to be a group selection claim. Yet it is popular with people who seem to reflexively condemn group selection. Perhaps they are more sophisticated than their rhetoric.

ETA:

Self-pollinators speciate and diversify more rapidly than SI species do.

Huh. maybe this isn't the red queen.

David Sloan Wilson wrote that "group selection is arguably the single most important concept for understanding the nature of politics from an evolutionary perspective."

DSW holds rather extreme views on the topic of group selection. I would classify this particular comment as being nonsense.

Thus demonstrating that a sort of species selection can exist, because species can't breed with each other and therefore can't be infected by SC genes from other species, while group selection can't exist, SC always infects.

The 1960's seem to have been a good time for theories about social processes, cooperation, and competition and they collected a lot of data based on the theories. I suspect that many of the broad conclusions from this era were frequently wrong, but the books they wrote have a lot of fascinating observations organized by these sorts of themes.

Your post-script reminded me of "noyau" from the book The Territorial Imperative (1966). A noyau in a canonical form is a geographic clumping of organisms of the same species who squabble and fight incessantly (which seems to indicate that they don't like each other's presence) but who do not actually seem to be constrained by environmental resource limitations from dispersing across the landscape. There is plenty of empty space, but they ignore it almost as if they are built so that they enjoy forming themselves into small groups and then dramatically squabbling with other small groups within the larger noyau.

I can imagine a lot of theories that might be made up to account for such observations, and I'm not sure of any of them are true so I won't bother with specific theorizing, but I just thought it would be interesting to other readers to read about these situations. Chapter five is the one specifically about noyau.

So why are so many species of Solanaceae still SC?

You must mean 'still SI'.

Regarding the terminology, if group selection translates to selection of a set of individuals, then how is group selection really valuably distinct from individual selection?

And, regarding the terminology, around “If group-level selection occurs at all, then traits of the group that are not genetic traits, including cultural knowledge, must be considered.” you seem to miss accounting for the possibility of individual selection for cultural units. And regarding those, analogously the first question again: is group selection of group of cultural units really meaningfully distinct from individual selection on a set of cultural units, as happens since time immemorial due to e.g. a weather event?

My suspicion is it isn’t, and - as you allude to - the false distinction is used to shoehorn wishes for altruism into evolutionary theory.

I would also go so far as to argue that the very concept of “group”, which supports this theory as well as the practice it refers to, is itself an individual cultural unit.

Thanks for raising this issue! I think resolving it could yield great benefits, and I’ll contribute to it when I can post on this forum.

What about group_selection_p, where group selection makes a gene that is already beneficial on the individual level spread even faster?

group\_selection\_p

Another interesting platform for kin vs. group selection is family Pyrolaceae (see Hideki Takahashi (1986) Pollen polyads and their variation in chimaphila (pyrolaceae), Grana, 25:3, 161-169) .

Without going into too much detail, it has about 4 genera; of them, Chimaphila has pollen organized into groups of about a hundred grains! It means that when the polyad (that's what the clump is called) lands on a stigma, multiple ovules (females) will get sperm (males) from the same father, and the resulting offspring should be much closer genetically than if multiple fathers contributed in equal measures. (My intuition is that fertilization is not frequent in these plants, though I have seen the fruits.) That is definite evidence for kin selection, isn't it? However, why is it not more widespread? "Three other generain the Pyrolaceae, Orthilia , Pyrola, and Moneses, have flowers with numerous ovules like that of Chimaphila, but the first of these produces pollen monads and the two others pollen tetrads." Also, [I think that] at least in Ukraine Orthilia and Pyrola are more common than Chimaphila (which is, even if actually true, only anecdotal evidence considering the total ranges of the genera.) (Another problem is that all those plants need fungal symbionts, and there's little data on their diversity.) What differencies in seed quality & dispersion, and population strategies would kin selection predict for Chimaphila and (Pyrola and Orthilia)?

Not from Solanaceae, but tangentially related. (It is studies like this one that set people like me to wonder at the selfing/crossing problem:)) possibly even a low-hanging fruit here:))

C. Montaner , E. Floris & J. M. Alvarez (2003): Study of pollen cytology and evaluation of pollen viability using in vivo and in vitro test, in borage (Borago officinalis L.) , Grana, 42:1, 33-37:

...It was stated that [borage's] pollen is difficult to germinate in vitro, it loses viability shortly after anther dehiscence and in the case of incompatible pollinations pollen tubes tend to be inhibited on the stigmatic surface (Mulcahy & Mulcahy 1983). Ghorbel and Nabli (1998) said that borage pollen remained dehydrated after self-pollination, like a sign of self-rejection. However, Crowe (1971) affirmed that the incompatibility reaction occurs after fertilization although our data (Montaner et al. 2000 a) demonstrated that there is not self-incompatibility and incompatible crosses have not been detected...

I mean, what the..? Is it, or is it not, self-incompatible?.. Although I must say that I haven't looked on articles citing this one.

selection at the level of a group

Is this supposed to mean: different groups exist, whose members' success or failure is tied together, so that we can sometimes expect to see group members with adaptations that would be self-destructive in the absence of its group?

I'm not sure from your essay what you mean by group selection at all.

Group selection, as I've heard it explained before, is the idea that genes spread because their effects are for the good of the group, or species. The whole point of evolution is that genes do well because of what they do for the survival of the gene. The effect isn't on the group, or on the individual, the species, or any other unit other than the unit that gets copied and inherited.

The question that seems obvious is how self-incompatibility ever evolved in the first place, It must have arisen in a species that was self-compatible, and then gradually have risen to fixation in that species. The opposite can happen.

Let's look at this from the point of view of a gene. Suppose a particular mutation in a single gene results in self-compatibility. What's the story for the gene? Let's suppose that it gives an overwhelming advantage over outside genes in fertilising itself, plus a normal chance at fertilising others. That gene ought to do well.

Well, maybe. If the plant has a typical set of recessive genes in its genome, self-fertilisation is a disaster. A few generations down the line, the self-fertilising plant will have plenty of genetic problems arising from recessive gene problems, and will probably die out. This means that self-fertilisation is bad - a gene for self-fertilisation will only prosper in those cases where it's not fertilising itself.

So let's change the scenario and assume the self-fertiliser manages to create a clone instead. Now many plants actually do cloning - it's not inherently a bad idea. But even a good clone is not as good as a gene pool. Your neighbouring plants further up the hill might have specific adaptations to the soil up there that yours doesn't have. The self-cloning plant can't live there. Further south, where the climate is different - your clone won't grow there. It will not spread throughout a whole range of environments as well as a species with an established gene pool can.

The general theme of clones is that they do very well for a while. But they can't spread outside their original environment because they can't reshuffle genes from the general gene pool. Then some disease springs up. Either it kills none of the clones, or essentially all of them. The regular gene pool suffers some losses, but has some survivors too.

Flowering is optional, but survival is compulsory. When times are hard, you put off sexual reproduction until later, and do just as well as any clone ever could. In really tough times, the variations in the sexual plants may prove to be the difference (for some of them) between survival and death, whilst all the clones end up perishing.

So many plants do a bit of both. They clone themselves when the going is good. Then they reproduce sexually after a while, when the benefits of rearrangement outweigh the costs of all the pollen, flowers etc. There are benefits, otherwise they wouldn't bother.

I'm not sure from your essay what you mean by group selection at all.

Group selection, as I've heard it explained before, is the idea that genes spread because their effects are for the good of the group, or species. The whole point of evolution is that genes do well because of what they do for the survival of the gene. The effect isn't on the group, or on the individual, the species, or any other unit other than the unit that gets copied and inherited.

The question that seems obvious is how self-incompatibility ever evolved in the first place, It must have arisen in a species that was self-compatible, and then gradually have risen to fixation in that species. The opposite can happen.

Let's look at this from the point of view of a gene. Suppose a particular mutation in a single gene results in self-compatibility. What's the story for the gene? Let's suppose that it gives an overwhelming advantage over outside genes in fertilising itself, plus a normal chance at fertilising others. That gene ought to do well.

Well, maybe. If the plant has a typical set of recessive genes in its genome, self-fertilisation is a disaster. A few generations down the line, the self-fertilising plant will have plenty of genetic problems arising from recessive gene problems, and will probably die out. This means that self-fertilisation is bad - a gene for self-fertilisation will only prosper in those cases where it's not fertilising itself. It will do worse.

So let's change the scenario and assume the self-fertiliser manages to create a clone instead. Now many plants actually do cloning - it's not inherently a bad idea. But even a good clone is not as good as a gene pool. Your neighbouring plants further up the hill might have specific adaptations to the soil up there that yours doesn't have. The self-cloning plant can't live there. Further south, where the climate is different - your clone won't grow there. It will not spread throughout a whole range of environments as well as a species with an established gene pool can.

The general theme of clones is that they do very well for a while. But they can't spread outside their original environment because they can't reshuffle genes from the general gene pool. Then some disease springs up. Either it kills none of the clones, or essentially all of them. The regular gene pool suffers some losses, but has some survivors too.

Flowering is optional, but survival is compulsory. When times are hard, you put off sexual reproduction until later, and do just as well as any clone ever could. In really tough times, the variations in the sexual plants may prove to be the difference (for some of them) between survival and death, whilst all the clones end up perishing.

So many plants do a bit of both. They clone themselves when the going is good. Then they reproduce sexually after a while, when the benefits of rearrangement outweigh the costs of all the pollen, flowers etc. There are benefits, otherwise they wouldn't bother.

I'm not sure from your essay what you mean by group selection at all.

Group selection, as I've heard it explained before, is the idea that genes spread because their effects are for the good of the species. The whole point of evolution is that genes do well because of what they do for the survival of the gene. The effect isn't on the group, or on the individual, the species, or any other unit other than the unit that gets copied and inherited.

The question that seems obvious is how self-incompatibility ever evolved in the first place, It must have arisen in a species that was self-compatible, and then gradually have risen to fixation in that species. The opposite can happen.

Let's look at this from the point of view of a gene. Suppose a particular mutation in a single gene results in self-compatibility. What's the story for the gene? Let's suppose that it gives an overwhelming advantage over outside genes in fertilising itself, plus a normal chance at fertilising others. That gene ought to do well.

Well, maybe. If the plant has a typical set of recessive genes in its genome, self-fertilisation is a disaster. A few generations down the line, the self-fertilising plant will have plenty of genetic problems arising from recessive gene problems, and will probably die out. This means that self-fertilisation is bad - a gene for self-fertilisation will only prosper in those cases where it's not fertilising itself. It will do worse.

So let's change the scenario and assume the self-fertiliser manages to create a clone instead. Now many plants actually do cloning - it's not inherently a bad idea. But even a good clone is not as good as a gene pool. Your neighbouring plants further up the hill might have specific adaptations to the soil up there that yours doesn't have. The self-cloning plant can't live there. Further south, where the climate is different - your clone won't grow there. It will not spread throughout a whole range of environments as well as a species with an established gene pool can.

The general theme of clones is that they do very well for a while. But they can't spread outside their original environment because they can't reshuffle genes from the general gene pool. Then some disease springs up. Either it kills none of the clones, or essentially all of them. The regular gene pool suffers some losses, but has some survivors too.

Flowering is optional, but survival is compulsory. When times are hard, you put off sexual reproduction until later, and do just as well as any clone ever could. In really tough times, the variations in the sexual plants may prove to be the difference (for some of them) between survival and death, whilst all the clones end up perishing.

So many plants do a bit of both. They clone themselves when the going is good. Then they reproduce sexually after a while, when the benefits of rearrangement outweigh the costs of all the pollen, flowers etc. There are benefits, otherwise they wouldn't bother.

Another recent article on group selection:

Henrich et al (2010). Markets, religion, community size, and the evolution of fairness and punishment. Science 327, March 19 2010, p. 1480.

Their theory: "Larger and more-complex societies prospered and spread to the degree that their norms and institutions effectively sustained successful interaction in ever-widening socioeconomic spheres, well beyond individuals' local networks of kin and long-term relationships."

Their evidence: "Using 3 behavioral experiments administered across 15 diverse populations, we show that market integration (measured as percentage of purchased calories) positively covaries with fairness while community size positively covaries with punishment."