Final answer:
The criterion under the biological species concept for identifying evolutionary independence is reproductive isolation, which prevents different species from interbreeding and maintaining separate genetic identities.
Step-by-step explanation:
Under the biological species concept, the criterion for identifying evolutionary independence is reproductive isolation. Reproductive isolation denotes a scenario where different species, due to various insurmountable barriers, cannot mate successfully or produce viable offspring.
For example, gorillas and bonobos (Pan paniscus) cannot interbreed, which demonstrates their reproductive isolation. This concept of species being reproductively isolated underpins the definition of a species, since it is this inability to successfully reproduce outside their group that maintains their unique genetic identities.
Speciation, the process by which new species arise, can also be driven by mechanisms aside from geographic isolation. These include ecological niches, morphological differences, reproductive barriers, and genetic changes, which can ultimately lead to the scientific definition of a subspecies.