Dictionary » A » Allele frequency

Allele frequency


noun, plural: allele frequencies

The frequency of an allele relative to that of other alleles of the same gene in a population.


It is usually expressed as a proportion or a percentage, and describes the amount of genetic diversity at the individual, population, or species level.

Example: assuming that in a human population, there are 100 individuals. Since each of them would have two alleles for a particular character (one allele inherited from the father, the other allele from the mother), the total number of genes in this population is 200 (=100 x 2).

If out of the 100 individuals, there are 30 homozygous for the dominant trait (AA), 50 are heterozygous (Aa), and the remaining 20 are homozygous for the recessive trait (aa). Therefore, the total number of dominant genes in the population is (30 x 2) + (50 x1) = 110. [That is, (30 x 2) from the 30 homozygous (AA) plus (50 x1) from the 50 heterozygous (Aa)] Thus, the frequency of the dominant trait (A) is (110/200) = 0.55 or 55%. Similarly, the total number of recessive genes in the population is (20 x 2) + (50 x 1) = 90. [That is, (20 x 2) from the 20 homozygous (aa) plus the (50 x 1) from the heterozygous (Aa)] The frequency of the recessive trait (a) is (90/200) = 0.45 or 45%.

Variant: allelic frequency.

Synonym: gene frequency.
See also: gene pool, allele, population.

User Contributions / Comments:

  • Chance events which may randomly alter allele frequencies are most likely to occur when population size is small.


Please contribute to this project, if you have more information about this term feel free to edit this page

Results from our forum

Microevolution verus Macroevolution

Evolution is defined as variation in the frequencies of alleles, where an allele is a specific iteration of a given gene. Microevolution ... version of the gene. Another useful example is extinction, in which the frequency of all alleles in a species go from some to none. What the creationist ...

See entire post
by hackenslash
Thu Mar 06, 2014 8:57 am
Forum: Evolution
Topic: Microevolution verus Macroevolution
Replies: 16
Views: 21686

Population genetics - make inferences from allele frequency

Hi if a mean allele frequency among multiple populations across a whole species distribution is 0.75 or 0.5, can you make any inference ...

See entire post
by Young
Sun Aug 25, 2013 10:52 pm
Forum: Genetics
Topic: Population genetics - make inferences from allele frequency
Replies: 1
Views: 1391

ecological genomics: Microsallites & allele frequency

... showed a significant correlations with an environmental variable(i.e. Allele 3 and Allele 7: texts in red colour). Values in the table indicate ... I have looked at correlations between an environmental gradient and a frequency of an allele. I know many studies have looked at genotypic diversity ...

See entire post
by Young
Tue Jul 23, 2013 5:30 am
Forum: Genetics
Topic: ecological genomics: Microsallites & allele frequency
Replies: 0
Views: 874

Genes in the same linkage group are inherited together?

Hi jonmoulton and wbla3335, Thanks for your post! So those 43 genes (alleles of them) in the same linkage group are inherited together. But how ... as 140cM away but still in the same linkage group! When you have allele frequency data of a particular gene and know which genes are in the same linkage ...

See entire post
by Young
Thu Jul 18, 2013 6:42 am
Forum: Genetics
Topic: Genes in the same linkage group are inherited together?
Replies: 5
Views: 3533

Re: Genetics Hard problem!

... genetic loci. (Note: One genetic map unit (m.u.) gives a recombinant frequency (RF) of 1 percent.) I scanned the whole passage in the attachment. ... So in the crossover, since crossover was done in between the two alleles, 100+34/200= 67amu. (wrong) Consider heterozygous parent contribution ...

See entire post
by Cat
Sun Jul 07, 2013 10:04 pm
Forum: PDF & Doc Files
Topic: Genetics Hard problem!
Replies: 2
Views: 4526
View all matching forum results

This page was last modified 23:18, 14 December 2009. This page has been accessed 40,043 times. 
What links here | Related changes | Permanent link