Genetics Question: Please answer and explain in detail. At the bottom of Table 1

Question

Genetics Question: Please answer and explain in detail.

At the bottom of Table 1 (Allele Frequencies) is given the value for Hobs, which stands for observed heterozygosity, because the heterozygosity observed often differs from what you expect. Think of heterozygosity as being the (expected) probability that an individual will be heterozygous at a given locus. What H is expected is calculated as follows.

The number of possible genotypes at a locus can be calculated using the formula k(k+1)/2, where k is the number of alleles at a particular locus. So, for example, one loci having two alleles (A, a) gives rise to three possible genotypes (AA, Aa, aa). The parameter k also represents the expected number of homozygous genotypes, and the total number of genotypes minus the number of homozygous genotypes equals the number of heterozygous genotypes. Or, put in equation form: k[(k-1)/2] represents the expected number of heterozygous genotypes. The percentage of individuals heterozygous for a given locus (i.e. the heterozygosity) is calculated from the allele frequencies, assuming independent assortment.

If the observed heterozygosity equals the expected heterozygosity, HOBS = 1. For each of the three loci examined in this lab HOBS is less than 1.0, meaning there are fewer heterozygotes than expected. Explain, in the space remaining on this page, what this says about population dynamics.

Explanation / Answer

Heterozygosity gives an idea of genetic variation within a population.

* The high heterozygosity indicates long-term natural selection for adaptation, to the mixing of strains of different populations or it indicates a negative assortive mating

* The low values of heterozygosity means isolation of a population and subsequent loss of genetic variation, due to inbreeding

* A reduction in observed heterozygosity indicates pooling of discrete subpopulations with different allele frequencies that do not interbreed

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