Gene Pools & Allele Frequency Definitions

Gene Pool

the total of all the genes/alleles present in a population.

Species

a group of organisms that can interbreed and produce fertile offspring.

Population

a group of organisms belonging to the same species in a particular area. All members of a population have the potential to interact and breed with each other. Individuals that are isolated from one another are members of different populations.

Allele Frequency

the proportion of each allele (different versions of a gene) within a population. The allele frequency can be calculated by converting the number of each allele to a percentage.

Genetic Variation

the number of different alleles (or allele combinations) within a population.

Genetic Drift

Any random change to the allele frequency of a population due to chance events.

Underlying principles of founder effect and population bottlenecks are the same. What are they?

A population is founded by, or reduced to a small number of survivors resulting in a loss of genetic diversity.

Gene Flow

Movement of genes into or out of a population, involving immigration and emigration.

Stabilising Selection

Favours the most common phenotype as the best adapted.

Directional Selection

Favours alleles that code for phenotypes at one extreme of a phenotypic range.

Disruptive Selection

Favours alleles that code for phenotypes at both extremes of a phenotypic range.

Population Bottleneck

Population is reduced to a small number of survivors.

Founder Effect

When a small group of individuals emigrate or become isolated from the original population, the colonising or founder population may not be a representative sample of the alleles in the parent population’s gene pool.

Inbreeding

Closely-related individuals produce offspring together. This reduces genetic diversity and is a problem for small populations.