Define species. Explain the various aspects of species.

Species is an interbreeding group of similar individuals sharing the common gene pool and producing fertile off spring. Species is considered a group of individuals which are:

• Reproductively isolated from the individuals of other species - (a breeding unit).
• Sharing the same ecological niche - (an ecological unit).
• Showing similarity in the karyotype - (a genetic unit). 
• Having similar structure and functional characteristic - (an evolutionary unit).