How is genetic polymorphism maintained in a population?

balanced polymorphism A genetic polymorphism that is stable and is maintained in a population by natural selection, because the heterozygotes for particular alleles have a higher adaptive value (i.e. fitness) than either homozygote.

What is genetic polymorphism?

Genetic polymorphism is defined as the inheritance of a trait controlled by a single genetic locus with two alleles, in which the least common allele has a frequency of about 1\% or greater. Genetic polymorphism is a difference in DNA sequence among individuals, groups, or populations.

What maintains genetic polymorphism?

One mechanism that can maintain polymorphisms is negative frequency-dependent selection on alternative alleles, whereby the fitness of each decreases as its frequency increases. Examples of frequency-dependent selection are rare, especially when attempting to describe the genetic basis of the phenotype under selection.

What is genetic polymorphism examples?

All the types of blood groups are the example of genetic polymorphism, such as the ABO blood group system. We see this system having more than two morphs: A, B, AB, and O are the variants present in the entire human population, but these groups vary in proportion in different parts of the world.

What’s a balanced polymorphism?

n. A system of genes in which two alleles are maintained in stable equilibrium because the heterozygote is more fit than either of the homozygotes.

What are examples of balanced polymorphism?

Sickle Cell disease is an autosomal recessive disorder that causes anemia, joint pain, a swollen spleen, and frequent, severe infections. It illustrates balanced polymorphism because carriers are resistant to malaria, an infection by the parasite Plasmodium falciparum that causes cycles of chills and fever.

What is balanced polymorphism?

A genetic polymorphism that is stable and is maintained in a population by natural selection, because the heterozygotes for particular alleles have a higher adaptive value (i.e. fitness) than either homozygote. From: balanced polymorphism in A Dictionary of Ecology »

What is a balanced polymorphism?

How does a polymorphism potentially occur?

DNA polymorphisms are produced by changes in the nucleotide sequence or length. These result from: (i) Variations in the fragment length pattern produced after digesting DNA with restriction enzymes, (ii) Variations in the size of a DNA fragment after PCR amplification, and (iii) Variations in the DNA sequence itself.

What occurs in genetic drift?

Genetic drift describes random fluctuations in the numbers of gene variants in a population. Genetic drift takes place when the occurrence of variant forms of a gene, called alleles, increases and decreases by chance over time. These variations in the presence of alleles are measured as changes in allele frequencies.

What does balanced polymorphism mean?

How are polymorphisms maintained in a population?

In very small populations, these polymorphisms may be eroded by genetic drift. Finally, again not completely stable, a polymorphism may be maintained by migration between population in which different variants are at an advantage.

What is genotype polymorphism?

Genetic polymorphism refers to the occurrence of two or more genetically determined phenotypes in a certain population, in proportions that the rarest of the characteristics cannot be maintained just by recurrent mutation (a general frequency of mutation).

What is the minimum frequency of a polymorphism?

In polymorphisms, there are two or more equally acceptable alternatives. To be classified as a polymorphism, the least common allele must have a frequency of at least 1\% in the population. If the frequency is lower than this, the allele is regarded as a mutation.

What is the effect of codon polymorphism on genetic drift?

There are vast amounts of polymorphism at the level of individual codons, and we have no idea what effects this has if any. In very small populations, these polymorphisms may be eroded by genetic drift.