Perplexed: In both group and individual selection, it is the species that evolves. But in species-level selection, the species does not evolve. It is selected—it either lives or dies.
Tim: Just because we are dealing with one individual, that doesn’t mean it doesn’t evolve.
Uh, I’m pretty sure I just stated that an individual—the species—does evolve. It evolves by way of organism-level or group-level selection. It just doesn’t evolve by going extinct or not.
“Does NOT evolve” was the term you used. However, with your clarification, it now looks as though this was mostly just a misunderstanding.
IMO, it is mostly OK to think of species level selection as a type of group selection—where the “groups” are species. Maybe there are some meanings of “group selection” for which this is bad—but I would say: mostly OK.
Yes, a population of 1 changes by mutation. Self-directed evolution is an example of that.
If you A) insist on a population having more than 1 member and B) define evolution in terms of genetic change in populations, then the conclusion is that one big organism would no longer be “evolving” when it changed—which I think would be a totally absurd conclusion—a sign that you had got into a terminology muddle.
That may not be a big deal for today’s organic evolution—but it makes a big difference for the study of cultural evolution. There, populations with only 1 member are much more common.
“Does NOT evolve” was the term you used. However, with your clarification, it now looks as though this was mostly just a misunderstanding.
IMO, it is mostly OK to think of species level selection as a type of group selection—where the “groups” are species. Maybe there are some meanings of “group selection” for which this is bad—but I would say: mostly OK.
Yes, a population of 1 changes by mutation. Self-directed evolution is an example of that.
If you A) insist on a population having more than 1 member and B) define evolution in terms of genetic change in populations, then the conclusion is that one big organism would no longer be “evolving” when it changed—which I think would be a totally absurd conclusion—a sign that you had got into a terminology muddle.
That may not be a big deal for today’s organic evolution—but it makes a big difference for the study of cultural evolution. There, populations with only 1 member are much more common.