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Co-dominant expression of genes for plumage colours. In cases of co-dominance, the genetic traits of both different alleles of the same gene-locus are clearly expressed in the phenotype. For example, in certain varieties of chicken, the allele for black feathers is co-dominant with the allele for white feathers.
1. Values for heterozygote inversions of the third chromosome were often much higher than they should be under the null assumption: if no advantage for any form the number of heterozygotes should conform to N s (number in sample) = p 2 +2pq+q 2 where 2pq is the number of heterozygotes (see Hardy–Weinberg equilibrium). 2.
In genetics, underdominance, also known as homozygote advantage, heterozygote disadvantage, or negative overdominance," [1] is the opposite of overdominance. It is the selection against the heterozygote , causing disruptive selection [ 2 ] and divergent genotypes .
Alternatively, a heterozygote for gene "R" is assumed to be "Rr". The uppercase letter is usually written first. [citation needed] If the trait in question is determined by simple (complete) dominance, a heterozygote will express only the trait coded by the dominant allele, and the trait coded by the recessive allele will not be present.
A heterozygote advantage describes the case in which the heterozygous genotype has a higher relative fitness than either the homozygous dominant or homozygous recessive genotype. Loci exhibiting heterozygote advantage are a small minority of loci. [1] The specific case of heterozygote advantage due to a single locus is known as overdominance.
X-linked dominant inheritance will show the same phenotype as a heterozygote and homozygote. Just like X-linked inheritance, there will be a lack of male-to-male inheritance, which makes it distinguishable from autosomal traits. One example of an X-linked trait is Coffin–Lowry syndrome, which is caused by a mutation in ribosomal protein gene ...
In medical genetics, compound heterozygosity is the condition of having two or more heterogeneous recessive alleles at a particular locus that can cause genetic disease in a heterozygous state; that is, an organism is a compound heterozygote when it has two recessive alleles for the same gene, but with those two alleles being different from each other (for example, both alleles might be ...
Since dominant traits mask recessive traits (assuming no epistasis), there are nine combinations that have the phenotype round yellow, three that are round green, three that are wrinkled yellow, and one that is wrinkled green. The ratio 9:3:3:1 is the expected outcome when crossing two double-heterozygous parents with unlinked genes.