What defines a species in biological terms?

The definition of a species in biological terms is primarily based on the ability of individuals within that group to interbreed and produce fertile offspring. This is known as the biological species concept. The focus is on reproductive isolation; if two populations can interbreed and produce viable, fertile offspring, they belong to the same species. This concept highlights the importance of gene flow between individuals, ensuring that they share a common gene pool which contributes to the evolutionary continuity of the species.

The other options, while they contain elements of biological classification, do not capture the essence of what defines a species as clearly. For instance, a population that shares a common environment does not necessarily mean they are of the same species, as they could be different species cohabiting the same area. A lineage of organisms that can survive in various habitats refers more to adaptability rather than species definition. Lastly, a collection of individuals with identical genetic makeup would suggest clonal organisms rather than a diverse population, which is often essential for species evolution and resilience. Therefore, the ability to interbreed and produce fertile offspring is the most accurate definition of a species in the context of biology.