Epigenetic Control of Genome Expression
From the standpoint of evolution, diploidy is generally considered advantageous for two reasons. First, because diploid organisms possess twice as many genes as haploids and in these conditions twice as many favorable mutations arise per generation. This of course increases the genetic diversity in the population and, finally, contributes to the progress of adaptive evolution. Diploidy is also considered advantageous because, when a recessive mutation occurs in a given gene, there is always a backup copy of the original allele on the other chromosome, offering a chance for the population to assess, with no risk, which one of the two alleles is most advantageous for the future of the species in a given environmental context. In most cases, the new mutant allele is neutral and has no selective advantage; sometimes it is harmful and is more or less rapidly eliminated. On rare occasions, it is beneficial and can then gradually replace the original allele.
KeywordsLong Terminal Repeat Imprint Gene Coat Color Robertsonian Translocation Uniparental Disomy
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