Genetic divergence

Overview of genetic divergence in evolutionary biology

Genetic Divergence

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Illustration of disruptive selection, a mechanism that can lead to genetic divergence.

Genetic divergence refers to the process by which two or more populations of an ancestral species accumulate independent genetic changes (mutations) through time, often after the populations have become reproductively isolated for some period. This divergence can lead to the formation of new species, a process known as speciation.

Mechanisms

Genetic divergence can occur through several mechanisms, including:

• Mutation: Random changes in the DNA sequence that can introduce new genetic variations.
• Genetic drift: Random fluctuations in allele frequencies that can lead to differences between populations over time.
• Natural selection: Differential survival and reproduction of individuals due to differences in phenotype, which can lead to adaptation to different environments.
• Gene flow: The transfer of genetic material between populations. Reduced gene flow can lead to divergence.

Role of Natural Selection

Natural selection plays a crucial role in genetic divergence, especially when populations are subjected to different environmental pressures. One form of natural selection that can lead to genetic divergence is disruptive selection, where extreme values for a trait are favored over intermediate values. This can result in a bimodal distribution of traits within a population, potentially leading to reproductive isolation and speciation.

Speciation

Genetic divergence is a key component of the speciation process. When populations become genetically distinct, they may develop reproductive isolation mechanisms, such as differences in mating behavior or timing, that prevent them from interbreeding. Over time, these isolated populations can evolve into distinct species.

Examples

• Allopatric speciation: Occurs when populations are geographically separated, leading to genetic divergence due to lack of gene flow.
• Sympatric speciation: Occurs without geographical separation, often through mechanisms like disruptive selection or polyploidy in plants.

Related Pages

• Evolutionary biology
• Population genetics
• Phylogenetics
• Adaptive radiation