Haldane’s sieve

It was repeatedly found that, in the natural population, the most common alleles are usually dominant and, on the other hand, minority alleles are frequently recessive. If, on the other hand, we isolate individuals in the laboratory that bear two newly formed mutated alleles, or if we obtain individuals bearing minority alleles in mutually isolated natural populations, then the relationship of partial dominance is mostly found between their alleles. The explanation suggested by Haldane says that suitable dominant alleles will be more readily spread in the population and will thus become majority alleles more readily than similarly advantageous recessive alleles. While the usefulness of dominant alleles is also manifested in a heterozygote, the usefulness of similar recessive alleles is manifested only in recessive homozygotes, in the outbred population, i.e. in a population in which random crossing occurs between its members, i.e. only when its frequency is substantially increased.

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The classical Darwinian theory of evolution can explain the evolution of adaptive traits only in asexual organisms. The frozen plasticity theory is much more general: It can also explain the origin and evolution of adaptive traits in both asexual and sexual organisms Read more