As far as I can tell, density-dependent selection is an entirely different concept from what I’m trying to get at here, and operates entirely within the usual paradigm that says natural selection is always optimizing for relative fitness. Yes, the authors are trying to say, “We have to be careful to pay attention to the baseline that selection is relative to”, but I think biologists were always implicitly careful to pay attention to varying baseline populations—which are usually understood to be species, and not ecological at all.
I’m trying to take a step back and say, look, we can’t actually take it for granted that selection is optimizing for reproductive fitness relative to ANY baseline in the first place; it’s an empirical observation external to the theory that “what reproduces, increases in prevalence” that evolution within sexual species seems to optimize for %-prevalence-within-the-species, rather than absolute size of descendants-cone.
Unfortunately you did nerdsnipe me with the ‘biologists think’ statement so I am forced to keep replying!
It’s worth noting that the original derivations of natural selection do use absolute fitness—relative fitness is simply a reparameterization when you have constant N (source: any population genetics textbook). This was why I brought up density-dependent selection, as under that framework N (and s) is changing, and selection in those circumstances is more complicated.
In fact, even under typical models, relative fitness and absolute fitness show interesting relations. See this paper by Orr where alleles (which in this model only affect relative fitness by increasing absolute fitness) show diminishing returns on excess fecundity. The first paper I sent you also explicitly says [that absolute fitness is required under N-varying s or T-varying N] in the abstract.
I thought you were making a more subtle point about the additional demands of life history theory vs. the pure allele-eye view, which I agree is interesting. I hope I have convinced you that biologists are already doing fruitful work in this area. I don’t understand the mesa-optimization arguments well enough to tell whether such an analogy is useful (to people who work in AI), but I do think it is true in at least a trivial sense.
As far as I can tell, density-dependent selection is an entirely different concept from what I’m trying to get at here, and operates entirely within the usual paradigm that says natural selection is always optimizing for relative fitness. Yes, the authors are trying to say, “We have to be careful to pay attention to the baseline that selection is relative to”, but I think biologists were always implicitly careful to pay attention to varying baseline populations—which are usually understood to be species, and not ecological at all.
I’m trying to take a step back and say, look, we can’t actually take it for granted that selection is optimizing for reproductive fitness relative to ANY baseline in the first place; it’s an empirical observation external to the theory that “what reproduces, increases in prevalence” that evolution within sexual species seems to optimize for %-prevalence-within-the-species, rather than absolute size of descendants-cone.
Unfortunately you did nerdsnipe me with the ‘biologists think’ statement so I am forced to keep replying!
It’s worth noting that the original derivations of natural selection do use absolute fitness—relative fitness is simply a reparameterization when you have constant N (source: any population genetics textbook). This was why I brought up density-dependent selection, as under that framework N (and s) is changing, and selection in those circumstances is more complicated.
In fact, even under typical models, relative fitness and absolute fitness show interesting relations. See this paper by Orr where alleles (which in this model only affect relative fitness by increasing absolute fitness) show diminishing returns on excess fecundity. The first paper I sent you also explicitly says [that absolute fitness is required under N-varying s or T-varying N] in the abstract.
I thought you were making a more subtle point about the additional demands of life history theory vs. the pure allele-eye view, which I agree is interesting. I hope I have convinced you that biologists are already doing fruitful work in this area. I don’t understand the mesa-optimization arguments well enough to tell whether such an analogy is useful (to people who work in AI), but I do think it is true in at least a trivial sense.