halbert said...
BB, the actual Darwinian principle (natural selection) is in play: The drugs create an environmental stress, and the cells that survive do so because they have some genetic difference which becomes an advantage for survival. By surviving, they become able to reproduce, passing on their genetic material to the next generation.
I agree 100% with everything after the word "play".
halbert said...
Using the term "mutation" is not really appropriate, because it implies an actual change at the genetic level. What is more likely--and more clearly understood--is that there is something in the gene that is either inherited directly or slightly different due to transcription error, which creates the evolutionary advantage.
Again, I pretty much agree. There may be some semantics involved here.
But, the terms "mutation(usually random mutation)" and "actual change" into new species, is exactly what I think of when I hear evolution of new species being discussed. Or as it was taught to me in my biology and anatomy and physiology classes decades ago, during college. We were taught that some sort of random mutation would occur, and if beneficial in the environment that species A was competing in, that creature would survive longer, thus having more time for reproduction, and thus this new beneficial trait would be passed on leading to a new species(after enough occurrences of such) that had more ability for survival. As opposed to simply selecting for something that is already there, like getting a big cow from a small cow, or one color from another. Traits that were already present and selected for by the breeder. Something that has been done for millennia.
Most of the sorts of things such as I see discussed in this article seem much more like the latter than the former. These moths that the first pesticides could not kill were already in the population in the first place. Having to compete against their brothers and sisters for resources. Th pesticide kills off most of the moths(or treatment most of the cancer cells), but the ones that are left already are immune to the pesticide, and now no longer have any competition from their bros. So they advance quickly and we can't hurt them until we come up with a new plan. But nothing new has come on the scene. It was already there, just held in check by the other moths. Until they were killed by us. Then it is party time for the survivors.
So none of this being described in this article- either the more resistant moths, cancer cells of I'm pretty sure most antibiotic resistant bacteria- seems like Darwinain evolution to me, as there is no apparent random mutation leading to something new, but rather just survival of some hardy types that are already there in the population. Sort of like when people survive- or especially never even become infected- some plague that kills 3 out of 4 people around them. But, I can certainly be wrong, or just not able to understand.
But even if I am right, I still think this whole concept of selecting for deadlier survivors is quite fascinating, whether or not they are evolving into something new, or they were already there to start with.
Post Edited (BillyBob@388) : 3/25/2019 12:26:25 PM (GMT-6)