Enter your allele A frequency, founders, generations, and growth rate — the Founder Effect Calculator returns final allele frequency, frequency change, genetic diversity (2pq), drift variance, and effective population size.
Final Allele A Frequency
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Frequency Change
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Final Effective Population Size
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Genetic Diversity (2pq)
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Drift Variance
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The founder effect occurs when a new population is established by a small number of individuals from a larger population, resulting in reduced genetic diversity and altered allele frequencies due to genetic drift.
Smaller populations experience stronger genetic drift. The variance in allele frequency change per generation is inversely proportional to the effective population size (variance ≈ pq/2Ne).
Effective population size (Ne) is the number of individuals contributing genes to the next generation. It's often smaller than the census population and determines the strength of genetic drift and loss of genetic diversity.
Population bottlenecks dramatically reduce population size temporarily, causing strong genetic drift that can significantly alter allele frequencies and reduce genetic diversity permanently.
Natural selection can counteract or enhance genetic drift effects. In small founder populations, drift may overpower weak selection, but strong selection can still maintain beneficial alleles.
Genetic diversity is measured as 2pq (heterozygote frequency under Hardy-Weinberg). It decreases in small populations due to genetic drift causing allele frequencies to move toward fixation (0 or 1).
Yes, if founders carry disease alleles at higher frequencies than the source population, or if genetic drift randomly increases disease allele frequencies in the small founding population.