Van Valen's (1976) Ecological species concept explains that a species taxon as a lineage of organisms is maintained and segmented by ecological forces. Accordingly, the species integrity is maintained by:

The ability of crop variety to become adapted to new climatic and edaphic conditions is called

The concept of Pureline was proposed by. in the year........ on the basis of his studies with beans (Phaseolus vulgaris) variety called