What does the biological species concept define?

The biological species concept defines a species as groups of interbreeding natural populations that are reproductively isolated from other such groups. This definition emphasizes the importance of reproductive isolation, which means that members of a species can breed with one another but not with individuals from other species. This reproductive barrier contributes to the maintenance of species integrity and prevents gene flow between different species, thus promoting speciation over time.

This concept focuses on the potential for interbreeding rather than relying solely on physical characteristics or genetic similarity. It allows for a dynamic understanding of how species can adapt and evolve in response to their environments while remaining distinct from others. The emphasis on natural populations also highlights that species are not just artificially defined groupings based on human classifications or observations, but rather reflect the realities of how organisms interact in their ecosystems.