Biological species concept definition
Biological Species Concept. The biological species concept defines a species as members of populations that actually or potentially interbreed in nature, not according to similarity of appearance.Although appearance is helpful in identifying species, it does not define species.Appearance isnt everything.1  Organisms may appear to be alike and be different species. 2  For example, Western meadowlarks (Sturnella neglecta) and Eastern meadowlarks (Sturnella magna) look almost identical to one another, yet do not interbreed with each otherthus, they are separate species according to this definition.ppearance isnt everything. 1  Organisms may appear to be alike and be different species. 2  For example, Western meadowlarks (Sturnella neglecta) and Eastern meadowlarks (Sturnella magna) look almost identical to one another, yet do not interbreed with each otherthus, they are separate species according to this definition.