Abstract:

Biologists believe that species is the basic unit of biological diversity, and few people will doubt the fact that there exist distinct species in nature. Nevertheless, despite of ceaseless debating on species concept or species definition among biologists over nearly a century, no consensus has been reached. Species definition concerns many biologists because it has far-reaching practical implications. Therefore, species concepts proposed by various scholars zero in greatly on their operational convenience and practical applicability in research activity such as taxonomic classification. As a result, these concepts and definitions are unavoidably shaped by the visions of the scholars which are further shaped by their insights into the evolutionary process of speciation. Speciation represents a stage in evolutionary divergence, and also different “species” may be at different stages of the speciation process. Since a “definition” is a kind of convention or confining description, every definition would bear some limitations. It would be thus very difficult, if not impossible, to define a perfect species concept that will accord with all species in taxonomic practice. From this perspective, we should confess that while every species concept or definition proposed thus far is reasonable, none is faultless or flawless. It is very important to bear this in mind, because, otherwise, one may stubbornly insist on one single species concept and introduces errors or even triggers chaos and confusion, consciously or unconsciously, in taxonomic and other evolutionary researches.

Key words: species, species concept, speciation, reproductive isolation, population subdivision, principle of divergence, magic trait