Movement contributes to gene flow when genetic material enters a population's reproduction.
Key knowledge
Gene flow transfers genetic variants among populations through reproductive contribution of migrants or transferred genetic material, such as pollen. It can alter allele frequencies and connect populations that would otherwise evolve separately.
Conditions and scope
Physical movement alone is insufficient if no genetic contribution reaches the recipient population.
Its effect depends on migration, reproduction and existing allele frequencies; it need not always increase local variation.
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References
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Gene flow transfers genetic variants among populations through reproductive contribution of migrants or transferred genetic material, such as pollen. It can alter allele frequencies and connect populations that would otherwise evolve separately.
Genetic contributions between populations can change variant frequencies.
If migrants form a specified fraction of a population's allele pool, the post-migration allele frequency is a weighted average of resident and migrant frequencies. Repeated replacement by a constant source population moves the recipient toward that source frequency under the model. Other forces and spatially reciprocal exchange can change this trajectory.
Migration changes genetic composition through effective contribution.
The D statistic compares two discordant allele-sharing patterns in an ordered four-sample test. Nonzero asymmetry can support gene flow under the null model, but ancestral subdivision and differential sequencing error can produce competing explanations.
Allele sharing tests a proposed gene-flow history against a stated ancestry model.