What defines a species in biological terms?

A species is commonly defined as a group of organisms that can interbreed and produce fertile offspring. This concept is known as the biological species concept, which emphasizes reproductive isolation as the key factor that distinguishes one species from another. When members of a species mate, the offspring they produce are capable of growing and reproducing as well, which is crucial for the continuation of the species.

This definition is particularly robust because it focuses on genetic continuity and the ability to share genes within a group. If organisms cannot reproduce with each other, even if they appear similar or live in the same environment, they would be considered distinct species. This principle helps biologists classify and understand the diversity of life on Earth as it relates to evolutionary biology and speciation.

Other definitions that might focus on habitat, food source, geography, or physical characteristics can be limiting or misleading; for example, two species may share a habitat but be entirely separate in their reproductive capabilities. Thus, the ability to generate fertile offspring is a crucial criterion in defining what constitutes a species.