Will geographical isolation be a major factor in the speciation of a self-pollinating plant species? Why or why not?

The geographical isolation cannot be a major factor in the speciation of a self-pollinating plant species because in the process of reproduction to be carried out it does not have to look at the other plants i.e, no new trait can become a part of the genotype in self-pollination plant species.However, there are chances of some variation that can occur due to the change in environment..