Species concept

Article By:

Wiley, Edward O., III Natural History Museum, University of Kansas, Lawrence, Kansas.

Last reviewed:June 2020

DOI:https://doi.org/10.1036/1097-8542.641300

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• Species concept, published June 2014:Download PDF Get Adobe Acrobat Reader

The idea that the diversity of life is divisible into a finite number of definable species. A species is a taxonomic category ranking immediately below a genus and including closely related, morphologically similar individuals that actually or potentially interbreed. Species concepts help to explain what a species is and how it came into being (see illustration). In general, species concepts grow out of attempts to understand the very nature of biological organization above the level of the individual organism. There are two basic questions: (1) What does it mean to be a species in general? Do all species have certain characteristics, such as forming genealogical lineages, just as all atoms have certain characteristics, such as the ability to undergo chemical reactions? (2) What does it mean to be a particular species? The first question addresses species concepts. The second question addresses how to apply a species concept to living organisms of the world. Does the name Homo sapiens apply to a group of organisms existing in nature? If so, does it belong, as a member, to a natural kind that can be characterized by some set of properties? The difference between the questions of what it is to be a species in general versus what does it mean to be a particular species represents the dividing line between what it is to be a natural kind and what it is to be a natural individual. See also: Biodiversity; Speciation

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