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Concept
Proles
Résumé
In biological taxonomy, race is an informal rank in the taxonomic hierarchy for which various definitions exist. Sometimes it is used to denote a level below that of subspecies, while at other times it is used as a synonym for subspecies. It has been used as a higher rank than strain, with several strains making up one race. Races may be genetically distinct populations of individuals within the same species, or they may be defined in other ways, e.g. geographically, or physiologically. Genetic isolation between races is not complete, but genetic differences may have accumulated that are not (yet) sufficient to separate species.
The term is recognized by some, but not governed by any of the formal codes of biological nomenclature. Taxonomic units below the level of subspecies are not typically applied to animals.
In botany, the Latin words stirps and proles were traditionally used, and proles was recommended in the first botanical Code of Nomenclature, published in 1868.
Races are defined according to any identifiable characteristic, including gene frequencies. "Race differences are relative, not absolute". Adaptive differences that distinguish races can accumulate even with substantial gene flow and clinal (rather than discrete) habitat variation. Hybrid zones between races are semi-permeable barriers to gene flow, see for example the chromosome races of the Auckland tree wētā.
The term race has also historically been used in relation to domesticated animals, as another term for breed; this usage survives in combining form, in the term landrace, also applied to domesticated plants. The cognate words for race in many languages (raza; Rasse; race) may convey meanings the English word does not, and are frequently used in the sense of 'domestic breed'.
If the races are sufficiently different or if they have been tested to show little genetic connection regardless of phenotype, two or more groups/races can be identified as subspecies or (in botany, mycology, and phycology) another infraspecific rank, and given a name.
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