Definition : Segregation of a population of a particular species by certain mechanisms, which prevent interbreeding among them, leads to Formation of a new species. Such mechanisms called as Isolation Mechanisms.
Introduction : “Species” Latin word- meaning kind or appearance.
- A species exist in nature as discrete units – demarcated from other species.
- The biological species concept defines a species as – A population or group of populations whose members have the potential to interbreed with one another in nature to produce viable, fertile offspring, but who cannot successfully interbreed with members of other species.
In other words,
- A biological species is the largest unit of population in which genetic exchange is possible, and that is genetically isolated from such populations.
- Each species is circumscribed by reproductive barriers that preserve its integrity as a species by blocking genetic mixing with other species.
Any factor that impedes/stops two species from producing viable, fertile offsprings contributes to reproductive isolation.
- Reproductive isolation prevents populations belonging to different species from interbreeding, even if their ranges overlap. The various reproductive barriers that isolate the gene pools of species can be categorized as Prezygotic or Postzygotic, depending upon whether they function before or after the formation of zygotes or fertilized eggs.
Importance of Isolating mechanism has been known for a long time Lamark and Darwin point out that interbreeding of distinct population results in swamping (mixing) of character. The role of it has been stressed by Wagner and Latter. The term Isolating mechanism was coined by Dobzansky (1937).