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?