Population Genetics

Organisms are members of a local population in which mating occurs at random. The study of the inheritance of factors in a population is concerned with the frequency of phenotypes and genotypes of the whole population rather than the ratios of characteristics among offspring examined in mendelian studies. A population is a group of organism that can freely interbreed. Some populations are open with immigrants of genes from overlapping population. Other populations are closed population cut off by barriers. In any of these populations the total of their genes located in reproductive cells make up the gene pool.

Gene Pool

All the alleles of all the genes of all the individuals in a population at any one time are known as the gene pool.

Population genetics is concerned with determining the relative proportions of the various genotypes present in a population, from which can be calculated the relative proportions of alleles in the population. This is known as allele frequency.

A population of organisms reproducing sexually produces a large amount of genetic variation. Each organism contains just one of the many possible sets of genes that can be formed from the pool. The gene pool remains stable if the environment is stable. However, if the environment changes some phenotypes will be advantageous and will be selected for, whilst others will be disadvantageous and will be selected against. Thus a gene pool is constantly changing, some alleles becoming more frequent and other less frequent. In some circumstances alleles may be totally lost from the gene pool.

Gene Frequencies Can…