Mechanisms of Evolution
Gene Pool Change
Key terminology for evolution
You need to be aware of some key definitions when discussing evolution/gene pool change.
Evolution: The process of gradual change in the gene pool of a population of organisms, which results in variation within a population, and eventually the development of a new species.
Population: A group of organisms which belong to the same species, which live in a particular area at a particular time.
Gene pool: The range of genes and alleles which are present in a population.
Species: A population of organisms that have the ability to interbreed and produce fertile offspring.
What are the mechanisms for gene pool change?
There are four main mechanisms for gene pool change. A fun mnemonic to remember these mechanisms is; Modern Giraffes Grow Necks.
Mutations in Sex Cells: This is a random process which generates new allele types. Mutations is the only generator of variety, and it may be spontaneous errors during DNA replication or it can be caused by an exposure to mutagens.
Genetic Drift: A random force leading to allele extinction. It involved the chance/random mating which can occur between members of a population. It is a strong force for gene pool change in small populations. (The bottleneck and founder effects are key knowledge points here!)
Gene Flow: The transfer of genes between populations. Migrating individuals will either add or remove alleles from any given population due to either leaving (emigration) or joining (immigration) a population.
Natural Selection: A non-random force which matches local environmental conditions with specific phenotype varieties. It shapes the allele frequencies in a population through the different reproductive rates of its members. Natural selection is a powerful force for change in larger populations.
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