Gene Pools
A gene pool represents the sum total of alleles for all genes present in a sexually reproducing population
Gene pools can be used to determine allele frequency – the proportion of a particular allele within a population |
Allele frequency:
- the proportion of an allele within a population
- allele frequencies range from 0 to 1.0, or as a percentage
- evolution always involves a change in allele frequency in a population's gene pool, over a number of generations
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Understanding:
10.3.U2: Evolution required that allele frequencies change with time in populations.
Objectives:
10.3.U2: Evolution required that allele frequencies change with time in populations.
Objectives:
- Define evolution.
- Outline five factors that can cause evolutionary change.
Evolution is the cumulative change in the heritable characteristics of a population across successive generations
Changes to allele frequency within a gene pool (evolution) can result from five key processes:
- This requires that allele frequencies change within the gene pool of the population to reflect these evolving characteristics
Changes to allele frequency within a gene pool (evolution) can result from five key processes:
- Mutation: A random change in the genetic composition of an organism due to changes in the DNA base sequence
- Gene flow: The movement of alleles into, or out of, a population as a result of immigration or emigration
- Sexual reproduction: Sex can introduce new gene combinations and alter allele frequencies if mating is assortative
- Genetic drift: The change in the composition of a gene pool as a result of a chance or random event
- Natural selection: The change in the composition of a gene pool as a result of differentially selective environmental pressures
Mechanisms for Changing Allele Frequency within a Gene Pool