Dominant

Definition

In ecology, a species that exerts disproportionate influence on community structure and ecosystem function through high abundance, biomass, or ecological effect; in genetics, an allele that expresses its phenotype when heterozygous with a recessive allele. Ecological dominance reflects competitive superiority, resource monopolization, or keystone effects rather than mere numerical abundance.

Etymology

Latin dominans, present participle of dominari 'to rule, govern'

Example

In eastern North American forests, the ant Formica exsectoides acts as a dominant by maintaining supercolonies that exclude other ground-foraging ants and regulate herbivore populations through aggressive tending of aphid herds.

Synonyms

• prevailing (ecological)
• predominant (ecological)

Related Terms

• Keystone species
• foundation species
• competitive exclusion
• recessive
• codominant
• ecological release
• Dominance hierarchy

Usage Notes

Ecological 'dominant' contrasts with 'keystone' (disproportionate effect regardless of abundance) and 'foundation' (physical habitat creation). In genetics, dominance describes allele interaction, not allele frequency—common recessive alleles remain recessive. Avoid conflating numerical dominance (sheer abundance) with functional dominance (ecological impact); a rare parasitoid may dominate host population dynamics.