Looking at the paper, I think I wasn’t tracking an important difference.
I still think that genes that have reached fixation among a population aren’t selected for, because you don’t have enough variance to support natural selection. The important thing that’s happening in the paper is that, because they have groups that colonize new groups, traits can reach fixation within a group (by ‘accident’) and then form the material for selection between groups. The important quote from the paper:
The total variance in adult numbers for a generation can be partitioned on the basis of the parents in the previous generation into two components: a within-populations component of variance and a between-populations component of variance. The within-populations component is evaluated by calculating the variance among D populations descended from the same parent in the immediately preceding generation. The between-populations component is evaluated by calculating the variance among groups of D populations descended from different parents. The process of random extinctions with recolonization (D) was observed to convert a large portion of the total variance into the between-populations component of the variance (Fig. 2b), the component necessary for group selection.
So even tho low fecundity is punished within every group (because your groupmates who have more children will be a larger part of the ancestor distribution), some groups by founder effects will have low fecundity, and be inbred enough that there’s not enough fecundity variance to differentiate between members of the population of that group, (even if fecundity varies among all beetles, because they’re not a shared breeding population).
[EDIT] That is, I still think it’s correct that foxes sharing ‘the fox genome’ can’t fix boom-bust cycles for all foxes, but that you can locally avoid catastrophe in an unstable way.
For example, there’s a gene for some species that causes fathers to only have sons. This is fascinating because it 1) is reproductively successful in the early stage (you have twice as many chances to be a father in the next generation as someone without the copy of the gene, and all children need to have a father) and it 2) leads to extinction in the later stage (because as you grow to be a larger and larger fraction of the population, the total number of descendants in the next generation shrinks, with there eventually being a last generation of only men). The reason this isn’t common everywhere is group selection; any subpopulations where this gene appeared died out, and failed to take other subpopulations down with them because of the difficulty of traveling between subpopulations. But this is ‘luck’ and ‘survivor recolonization’, which are pretty different mechanisms than individual selection.
This is a little like game theory coordination vs cooperation actually. Coordination is if you can constrain all actors to change in the same way: competition is if each can change while holding the others fixed. “Evolutionary replicator dynamics” is a game theory algorithm that encompasses the latter.
Even if the beetles all currently share the same genes, any one beetle can have a mutation that competes with his/her peers in future generations. Therefore, reduced variation at the current time doesn’t cause the system to be stable, unless there’s some way to ensure that any change is passed to all beetles (like having a queen that does all the breeding).
Looking at the paper, I think I wasn’t tracking an important difference.
I still think that genes that have reached fixation among a population aren’t selected for, because you don’t have enough variance to support natural selection. The important thing that’s happening in the paper is that, because they have groups that colonize new groups, traits can reach fixation within a group (by ‘accident’) and then form the material for selection between groups. The important quote from the paper:
So even tho low fecundity is punished within every group (because your groupmates who have more children will be a larger part of the ancestor distribution), some groups by founder effects will have low fecundity, and be inbred enough that there’s not enough fecundity variance to differentiate between members of the population of that group, (even if fecundity varies among all beetles, because they’re not a shared breeding population).
[EDIT] That is, I still think it’s correct that foxes sharing ‘the fox genome’ can’t fix boom-bust cycles for all foxes, but that you can locally avoid catastrophe in an unstable way.
For example, there’s a gene for some species that causes fathers to only have sons. This is fascinating because it 1) is reproductively successful in the early stage (you have twice as many chances to be a father in the next generation as someone without the copy of the gene, and all children need to have a father) and it 2) leads to extinction in the later stage (because as you grow to be a larger and larger fraction of the population, the total number of descendants in the next generation shrinks, with there eventually being a last generation of only men). The reason this isn’t common everywhere is group selection; any subpopulations where this gene appeared died out, and failed to take other subpopulations down with them because of the difficulty of traveling between subpopulations. But this is ‘luck’ and ‘survivor recolonization’, which are pretty different mechanisms than individual selection.
This is a little like game theory coordination vs cooperation actually. Coordination is if you can constrain all actors to change in the same way: competition is if each can change while holding the others fixed. “Evolutionary replicator dynamics” is a game theory algorithm that encompasses the latter.
Even if the beetles all currently share the same genes, any one beetle can have a mutation that competes with his/her peers in future generations. Therefore, reduced variation at the current time doesn’t cause the system to be stable, unless there’s some way to ensure that any change is passed to all beetles (like having a queen that does all the breeding).