Geenilukujen

Geenilukujen, sometimes referred to as gene counting, is a term used in the field of genetics and population genetics to describe the process of determining the frequencies of different alleles at specific genetic loci within a population. This information is crucial for understanding the genetic diversity of a population, estimating heterozygosity, and calculating genetic distances between populations.

The fundamental principle behind gene counting is that by sampling individuals from a population and examining their genotypes at one or more loci, one can infer the proportions of the different alleles present in the gene pool. For a diploid organism, an individual can be homozygous for a particular allele (possessing two copies of it) or heterozygous (possessing one copy of two different alleles). By summing up the number of copies of each allele across all individuals in the sample, and then dividing by the total number of alleles present (which is twice the number of individuals sampled), allele frequencies can be calculated.

For example, at a single locus with two alleles, A and a, if a sample of 100 individuals contains 80 individuals with the genotype AA, 15 individuals with the genotype Aa, and 5 individuals with the genotype aa, then the total number of A alleles is (80 * 2) + 15 = 175, and the total number of a alleles is 15 + (5 * 2) = 25. The total number of alleles is 100 * 2 = 200. Therefore, the frequency of allele A is 175/200 = 0.875, and the frequency of allele a is 25/200 = 0.125. These frequencies sum to 1.0, as expected. Gene counting is a foundational technique in many population genetic analyses.