XIII.3.1.3.2 Diploidy helps maintain intrapopulation and intraspecific polymorphism

Diploidyis an important mechanism capable of assisting in maintenance of intrapopulation and intraspecies polymorphism.The very fact that diploidy enables the existence of genetic recessivity and dominance and that simultaneously selection against recessive traits is rather ineffective (IV.6.2) means that a great many different alleles, including those that reduce the fitness of their carriers, can survive for long periods of time in the population.Systems in which selection against both homozygotes occurs even permit permanent maintenance of polymorphism in the population.Sections XIII.3.1.2 and XIII.3.1.2.1 describe the possible advantages of maintenance of intrapopulation polymorphism.

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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
Draft translation from: Evoluční biologie, 2. vydání (Evolutionary biology, 2nd edition), J. Flegr, Academia Prague 2009. The translation was not done by biologist, therefore any suggestion concerning proper scientific terminology and language usage are highly welcomed. You can send your comments to flegratcesnet [dot] cz. Thank you.