Subspecies

A subspecies is a taxonomic rank below species for a distinct population or group of populations within a species. Its members differ consistently from other populations but remain capable of belonging to the same species.

Species: A basic taxonomic unit grouping organisms that share a recognized pattern of evolutionary or reproductive cohesion. Subspecies are named divisions within this broader taxonomic rank.
Trinomial nomenclature: A naming convention that uses three terms to identify a taxon below species, such as a subspecies. It is the standard format for many zoological subspecies names.
Variety (botany): A botanical taxonomic rank below species, generally used for distinctions less extensive than subspecies. Botanical classifications often use variety where zoological practice might use subspecies.
Bengal tiger: A tiger population native primarily to the Indian subcontinent, commonly classified as Panthera tigris tigris. Its trinomial name is a familiar example of a named subspecies.
Population: A group of organisms of the same species living in a particular area and interacting as a population. Subspecies classifications commonly describe differentiated populations.
Clinal variation: Gradual change in a biological trait across a geographic or environmental gradient. Continuous clines complicate drawing sharp boundaries between subspecies.
Ecotype: A genetically distinct population adapted to particular environmental conditions within a species. Ecotypes describe adaptive differences without necessarily asserting formal taxonomic rank.
Gray wolf: A widely distributed canid species with populations that vary in appearance, ecology, and classification. Wolf subspecies illustrate how geographic variation can produce competing taxonomic treatments.
Geographic variation: Differences in biological traits among populations living in different geographic areas. Geographic variation often supplies the evidence used to distinguish subspecies.
Genetic differentiation: Differences in genetic composition among populations caused by limited gene flow, drift, selection, or other forces. Genetic evidence can reveal whether named populations are meaningfully differentiated.

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