Race (taxonomy)
An informal taxonomic rank for intraspecies populations.
In biological taxonomy, race is an informal rank used to denote genetically distinct populations within a species, often below the subspecies level. It is not governed by formal codes of nomenclature and may be defined by geographic, physiological, or genetic criteria. Genetic isolation between races is incomplete, but differences can accumulate without reaching species-level separation.
Quick Facts
- Field
- Biological taxonomy
- Known for
- Informal taxonomic rank below subspecies
Facts from the source article.
Definitional approaches
Races are defined by any identifiable characteristic, including gene frequencies, and their differences are relative rather than absolute. Adaptive distinctions can persist despite gene flow and clinal habitat variation, with hybrid zones acting as semi-permeable barriers. The term also historically referred to domesticated breeds, surviving in the term landrace for plants and animals.
Distinguishing from other taxonomic ranks
When races are sufficiently distinct or show little genetic connection regardless of phenotype, they may be elevated to subspecies or another infraspecific rank. Ernst Mayr described a subspecies as a geographic race worthy of a separate name. Study of preliminary races can lead to new species classification, as with two brown planthopper populations in the Philippines reclassified as distinct sympatric species based on host adaptation, hybridization barriers, and behavioral differences. For pathogenic bacteria, races may be named as pathovars, while for parasitic organisms under botanical nomenclature, the term forma specialis is used.
In mycology and phytopathology
Fungal races are frequently classified in mycology and phytopathology, with the term 'physiologic race' recommended at the 1935 International Botanical Congress. Modern usage groups races by virulence on particular host plants. Commercial melon production has faced an arms race against cucurbit powdery mildew caused by successive races of Podosphaera xanthii, prompting development of resistant cultivars. A 2004 review noted race identification is important for research and the seed industry but has limited horticultural utility due to rapid pathogen population changes. Classification is complicated by environmental effects on host responses and difficulties in identifying genetic differences between putative races.
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