What is isolation?
Is isolation the segregation of population into smaller units or/and separation of different species by certain mechanism?
Through the process of natural selection there are genetic variations that appear in population. Isolation is considered to be a mechanism in evolution that helps to preserve specisies that carry these genetic varieties. According to T. Dobzhansky (1937), there are two main isolation mechanims: geographical and reproductive. Geographical isolation is achieved by the landscape barriers. Reproductive isolation prevents genes exchange between populations due to genetically controlled mechanisms (e.g., incompetibility of the reproductive systems, unattractiveness).