Garte: The Meaning of "Random" Mutation

[BruceS]

@Mercer

1. Some characteristics of mutations are not independent–frequency, location, direction.

Thanks for this feedback. Do I understand you correctly in saying that specific features of the environment affect the location and direction of mutations? And further, that which location and which direction is correlated with (and so depends on causally on ) some identifiable characteristic of the environment?

On frequency: does this add something over the other variables. Or does it just mean that a stressed population with the same starting genome will produce more of the non-independent type of mutations (ie location, direction) in a given time frame than will a non-stressed one.

2. Others are–fitness. This is the one that is being challenged rhetorically, but not empirically.

BruceS:

I understand that mutations are not independent of fitness (where fitness is measured by relative reproductive success). For example, any mutation which kills its inheritors is not going to be fit in that sense!

I don’t see how the latter sentence supports the former.

Yes, i did not express that link. I had something in mind which I failed to express.

I am assuming that the types of mutations which Joshua listed in the other thread (link below) have the effect of conserving the ability for the inheritor to successfully reproduce, which would make them more fit than a purely random change. But the resulting mutations are still independent of specific characteristics of the environment.

But that understanding of the list is based only a cursory attempt to understand that list.

This is the Joshua’s post with the list I am referring to

Mutation is Biased Towards Fitness

@Agauger so good to see you here again. There are several examples of this. One very commonly known one is that transitions are simultaneously: More common than transversions. The cause of this is at least in part because of the biochemistry of mutations. More likely to be a conservative amino acid substitution. This cause of this at least in part is the structure of the of the genetic code. Because fitness is intertwined with mutational bias in this case it is hard to untangle some key features of the data. An example of one attempt to do so is here: https://academic.oup.com/mbe/article/19/7/1022/1068565. There are other examples too. Recombination allows for shuffling of a genome in a manner very likely not to cause harm, and increases (perhaps even dramatically) the chance of causing benefit. Copy number variation another example of a mutational mechanism that is not likely to cause harm (thought it sometimes can), but increases the chances of causing benefit. Mutat…