Mayr (1970) defined speciation as 'the creation of species'. Species can be defined as one of the basic units of biological classification, a group of organisms capable of interbreeding and producing fertile offspring. The process of speciation is possible by a few mechanisms, one of them being - Allopatric Speciation.
In this scenario, a population splits into two geographically isolated populations by some - geographic barrier / extrinsic barrier / unfavourable habitat. Once a barrier is placed, speciation is only a matter of time (e.g. mountain range for terrestrial animals, land mass for aquatic animals). The geographical barrier leads to reproductive isolation and eventually reproductive barrier. The organism undergoes evolutionary change over many generations because:
- they become subjected to dissimilar selective pressures,
- different mutations arise in them,
- they independently undergo genetic drift.
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