Speciation

Speciation is the process by which a new species is formed from a pre-existing one. A species, in this context, is defined as a group of similar organisms that are capable of interbreeding with one another and of producing fertile offspring under natural conditions. New species can arise through several distinct modes.

a. Intraspecific Speciation :

i. Allopatric speciation : It is the formation of a new species due to the separation of a segment of a population from its original population by distance or by a geographical barrier cutting across the species range, e.g. creeping glaciers or the development of mountains; migration of individuals also causes allopatric speciation. The mode of evolution here is called adaptive radiation, e.g. the 14 different species of finches of the Galapagos Islands and the several marsupial species of the Australian continent.

ii. Sympatric speciation : It is the formation of species within a single population without geographical isolation; such species are formed due to reproductive isolation, e.g. the cichlid fishes of Lake Victoria. Mutations are helpful in sympatric speciation.

b. Interspecific Speciation : …