Why are Darwinian variations considered directional?

[Kitrak]

I read that Darwinian mutations are considered as small and directional mutations. Why is that? Regardless of the type of mutation, a mutation (or a variation) is directionless- they are random. From what I understand, the direction is given to these variations through environmental and evolutionary stresses. For a given gene, there may be many different variations due to mutations, but the one which leads to speciation (the one which is naturally selected, a Darwinian variation, I suppose?) is merely chosen through natural selection. Is this correct? Or am I missing something?

 

[Ygggdrasil]

I read that Darwinian mutations are considered as small and directional mutations. Why is that? Regardless of the type of mutation, a mutation (or a variation) is directionless- they are random. From what I understand, the direction is given to these variations through environmental and evolutionary stresses. For a given gene, there may be many different variations due to mutations, but the one which leads to speciation (the one which is naturally selected, a Darwinian variation, I suppose?) is merely chosen through natural selection. Is this correct? Or am I missing something?

I'm not sure what you mean by Darwinian mutation as that's not a term I've come across before. Do you have a source for these statements to put them in context?

Anyway, you are thinking about things in the right way. Mutations occur randomly and can have a variety of effects. Many mutations are deleterious (they harm the fitness of the organism), many are neutral, and some small fraction are beneficial. You are correct in stating that the direction comes from environmental factors placing selection pressure on the population such that individuals harboring beneficial mutations are more likely to reproduce than than the individuals harboring deleterious mutations. Mutations create variation within a population and evolution acts on that variation to select for beneficial traits.

 

[Suraj M]

I don't think there is a term like Darwinian mutation, it's Darwinian Variation, I thinks that's what is throwing you off.
They aren't saying that the mutation is directional.