interfertile

Interfertile refers to the ability of different species or subspecies to interbreed and produce fertile offspring. This concept is primarily applied in biological classification and understanding reproductive isolation. When two groups are interfertile, it suggests they are closely related and may not be entirely separate species, or at least represent populations that have not yet fully diverged.

The degree of interfertility can vary. Some pairings may produce offspring that are viable but sterile, like a mule (offspring of a horse and a donkey). In such cases, while interbreeding is possible, the offspring cannot reproduce, indicating a significant genetic barrier. Complete interfertility, where offspring are both viable and fertile, suggests a very close genetic relationship, often within the same species or between very closely related species that can still exchange genes.

The concept of interfertility is central to the biological species concept, which defines a species as a group of organisms that can interbreed naturally and produce fertile offspring. However, this definition has limitations, particularly with asexual organisms or populations that are geographically separated and thus cannot interbreed even if they are interfertile. Understanding interfertility helps scientists delineate species boundaries and trace evolutionary relationships. It highlights the dynamic nature of speciation, where reproductive isolation is a key factor in the formation of new species.