frequency-dependent selectionとは 意味・読み方・使い方

Frequency-dependent selection is the term given to an evolutionary process where the fitness of a phenotype is dependent on its frequency relative to other phenotypes in a given population. In positive frequency-dependent selection (or purifying frequency-dependent selection) the fitness of a phenotype increases as it becomes more common. In negative frequency-dependent selection (or diversifying frequency-dependent selection) the fitness of a phenotype increases as it becomes rarer. Negative frequency-dependent selection is an example of balancing selection. Frequency-dependent selection is usually the result of interactions between species (predation, parasitism, or competition) or between genotypes within species (usually competitive or symbiotic), and has been especially frequently discussed with relation to anti-predator adaptations. Frequency-dependent selection can lead to polymorphic equilibria which result from interactions among genotypes within species in the same way that multi-species equilibria require interactions between species in competition (e.g. where α_ij parameters in Lotka-Volterra competition equations are non-zero).