What is a species?

The definition of a species primarily revolves around the ability of organisms to interbreed and produce fertile offspring. This concept is known as the biological species concept, which characterizes a species as a group of individuals that can mate with one another and have viable offspring capable of reproducing. This is crucial because it reflects the genetic continuity of a species and helps maintain its unique characteristics over time.

In this context, the other options do not accurately capture the essence of what defines a species. For instance, a group of genetically identical organisms refers to clones, which do not encompass the broader criteria of genetic diversity and reproductive capabilities that characterize a species. Similarly, a large population simply denotes quantity and geography but fails to address the reproductive aspect that is critical to defining a species. Lastly, an isolated group with distinct characteristics might suggest speciation, but it does not necessarily highlight the ability to interbreed and produce fertile offspring, which is fundamental to the concept of a species. Therefore, the correct understanding emphasizes reproductive compatibility as the defining factor for species classification.