Q.Define species. Explain the various aspects of 'species'.

A species is a group of similar, interbreeding organisms producing fertile offspring and reproductively isolated from others; it is viewed morphologically, biologically and evolutionarily.

Definition:

• A SPECIES is the basic (fundamental) unit of biological classification.
• It is defined as a group (or population) of organisms that are essentially SIMILAR in their morphological (structural) features and are capable of INTERBREEDING freely among themselves to produce FERTILE offspring, while being reproductively ISOLATED from members of other species.

Various aspects of 'species':

1. Morphological aspect (Morphological species):

• All members of a species share a basically similar structure (morphology and anatomy); this was the earliest criterion (used by Linnaeus).

2. Biological aspect (Biological species concept):

• Given by Ernst Mayr; a species is a group of naturally interbreeding populations that produce fertile offspring and are reproductively isolated from other groups (they cannot successfully interbreed with other species). This emphasises reproductive isolation.

3. Genetic / Evolutionary aspect: …