What leads to a species being defined in biological terms?

The concept of a species in biological terms is primarily centered on the ability of individuals to interbreed and produce viable offspring. This definition is part of the biological species concept, which emphasizes reproductive isolation as a key factor in distinguishing one species from another. If two populations can mate and produce fertile offspring, they are considered to belong to the same species, whereas reproductive barriers—such as differences in mating habits or genetic compatibility—keep different species from interbreeding successfully.

Factors such as adaptability to environmental changes, geographic presence, and similarity in appearance and behavior can all play roles in a species' survival and classification, but they do not define a species in the biological sense. These aspects may help us understand species interactions and distributions but do not capture the essence of what determines species status. The core of the definition lies in reproductive potential and the capability of maintaining the continuity of genetic traits through successive generations.