Geographical isolation will be a major factor in the speciation of an organism that reproduces sexually. It leads to the change in gene frequency leading to the expression of one type of traits in a geographically isolated population. In case of an asexually reproducing organism, geographical isolation cannot be a major factor is speciation because meiosis does not take place during asexual reproduction. Hence, there very rare chances of variation and without variation, there cannot be speciation.
