Mayr (1969) defined a sub-species as a drographically isolated population of a species which are capable of interbreeding and producing fertile hybrids.
(i) A sub-species is a sub-division of species.
(ii) Each sub-species has a geographical area and is geographically isolated from other species.
(iii) Different sub-species are not reproductively isolated. But they are capable of interbreeding.
ADVERTISEMENTS:
(iv) The morphological difference between two sub-species is negligible.
(v) Hybrids or intermediate forms are produced when two neibouring sub-species interbreed.
Examples of Sub-Species:-
The bird, golden whistler (pachycephala pectoralis) living on Solomon Islands in the tropical pacific ocean.
ADVERTISEMENTS:
Thus sub-species are small step in the origin species.