Comment by macleginn
5 hours ago
There has been aruably a more serious blow to the pure Darwinian evolution (this is all epigenetics, after all): non-random occurrence of useful mutations in populations exposed to particular diseases.
5 hours ago
There has been aruably a more serious blow to the pure Darwinian evolution (this is all epigenetics, after all): non-random occurrence of useful mutations in populations exposed to particular diseases.
I wonder how that works? Speculation: there is some kind of genetic/epigenetic signalling which modulates DNA repair mechanisms, such that certain DNA regions can be marked as more mutation-prone than others. And there may be selective pressure to make genes associated with disease-resistance more mutation-prone, because that’s a gene whose mutation is more likely to be beneficial (compensating mutations for evolution in existing diseases or to respond to new diseases), less likely to be harmful (most of the time, most likely outcome of the “wrong” mutation would be less resistance to diseases, but it probably wouldn’t otherwise be lethal or cause serious disability). But if that is what is actually going on here, is there any actual challenge to Darwin’s views? He didn’t know about DNA; I don’t think he ever claimed all mutations were equally likely (why would he when he had no idea what the actual mechanisms behind them were)
I don’t really see that as anti-Darwinian. Those genes successfully attach themselves to a new organism and provide advantages such that they are selected for in the population.
The selection is classical, but the mutations are supposed to be random, not skewed towards more useful genetic variants. One can speculate that a purely random (and otherwise neutral, say) prior mutation led to this directionality, but the actual resulting mechanism is AFAIK still unknown.
plasmids
https://en.wikipedia.org/wiki/Plasmid