Understand the concept of a gene pool 3. The Gene Pool Understand the concept of a gene pool

The Gene Pool

Keywords Population: A group of interbreeding individuals of one species in a certain area. Gene Pool: All the genes, including all the different alleles for each gene, that are present in a population at any one time. Locus: The location of a gene or specific gene sequence on a chromosome.

Example of a gene pool

Expressing Allele Frequency We can quantify gene pools by calculating the frequency of an allele: Eg: population of 20 individuals = 40 alleles at a particular locus. 8 homozygous dominant, 6 homozygous recessive, 6 heterozygous How many of each individual allele exist? B = 8 x 2 + 6 =22 b = 6 x 2 +6 = 18 f(B) = 22/40 = 0.55 f(b)= 18/40 = 0.45

A large gene pool (range of alleles) Is a good thing as it provides a source of variation for any changes that may occur in the environment. It is also big enough to resist changes from death, random events and disease. Populations which can interbreed with neighbouring populations are more likely to survive changes as their total gene pool is the sum of the two populations.

Purebreeding reduces the gene pool Purebreds or purebreeds, are cultivated varieties of an animal species, achieved through the process of selective breeding. If the lineage of a purebred animal is recorded, then that animal is said to be pedigreed. Because pure-breeding creates a limited gene pool, purebred animal breeds are also susceptible to a wide range of congenital health problems. Breeding from too small a gene pool, especially direct inbreeding, can lead to the passing on of undesirable characteristics or even a collapse of a breed population due to inbreeding depression.