Geographical isolation can be defined to a population of plants, animals or some other organism that is separated by the exchange of genetic materials with other organism of the same species.
Geographical isolation is the caused intentionally or by coincidence. Gene flow can be caused naturally or man made. The naturally occurring barriers are mountains, deserts and mountains et cetera.
The man made barriers such as the great wall of china acts as the barrier for the plant species. Example: Ziziphus jujuba, prunus and some species grow only on the other side of the wall.
