What is an example of heterozygote advantage?

Heterozygous advantage is one of several controversial explanations for the existance of genetic variability in natural populations. The classic example of heterozygous advantage is sickle cell anemia where humans who are homozygotic for sickle shaped cells (pictured opposite) suffer from a near lethal condition.

What is an example of a heterozygote?

If the two versions are different, you have a heterozygous genotype for that gene. For example, being heterozygous for hair color could mean you have one allele for red hair and one allele for brown hair. The relationship between the two alleles affects which traits are expressed.

Does heterozygote advantage lead to fixation?

The larger range of adaptive mutations available to diploids comes with a catch, however; many of these adaptive mutations display heterozygote advantage, and thus will not simply go to fixation.

What type of selection is heterozygote advantage?

In heterozygote advantage, or heterotic balancing selection, an individual who is heterozygous at a particular gene locus has a greater fitness than a homozygous individual. Polymorphisms maintained by this mechanism are balanced polymorphisms.

When does a heterozygote have a superiority over a homozygous?

Heterozygote superiority (heterozygous advantage) describes the case in which the heterozygous genotype has a higher relative fitness than either the homozygous dom- inant or homozygous recessive genotype. In population studies, mean fitness of hetero- zygotes is higher than the mean fitness of all homozygotes, but in laboratory studies and evo-

When does an allele have a heterozygote advantage?

Since cholera is transmitted through water, modern sanitation has made it rare. When a single copy of a disease allele doesn’t result in a disease but instead is good for the person or organism that carries it, we say that allele has a heterozygote advantage.

How is overdominance related to the phenotype of the heterozygote?

Overdominance is a condition in genetics where the phenotype of the heterozygote lies outside of the phenotypical range of both homozygote parents, and heterozygous individuals have a higher fitness than homozygous individuals.

What is the segregational load due to heterozygote advantage?

In the case of heterozygote advantage, the load due to a single locus is st / ( s + t) ( Charlesworth and Charlesworth, 2010 ). Equation [4] can be used to determine the segregational load contributed by a large number of polymorphic loci with independent effects. This can be considerable, even if selection is weak.