Differentiate between allopatric and sympatric species.

Features Allopatric Speciation Sympatric Specieation Geographical isolation Allopatric speciation occurs when a species separates into two separate groups which are isolated from one another due to geographical separation. In sympatric speciation, new species forms in absence of geographic isolation. Responsible Factors In allopatric speciation, species experience different selection pressures and the advantageous allele is selected. The increased frequency of an advantageous allele in each population, becoming too different can no longer breed. In Sympatric speciation, mutations can occur that cause the organism to have an increased number of chromosomes known as polyploidy, this can cause mechanical isolation, temporal isolation or behavioural isolation.