Genetic Dynamics of Range Expansion

The genetic dynamics of range expansion encompass changes in genetic diversity and structure that occur as species or populations spread into new territories. Range expansions typically involve serial founder events, where small subsets of the expanding population colonise successive habitats, leading to gradients of decreasing genetic variation and pronounced genetic drift at the leading edge. These processes can enable deleterious alleles to increase in frequency by surfing on the expansion front, alter the efficacy of natural selection and shape adaptive potential. The interplay between mutation supply, stochastic demographic events and spatial selection gradients gives rise to phenomena such as expansion load, mutation surfing and spatial heterogeneity of introgression during invasions. Empirical studies—from microbial colonies to insect and vertebrate invasions—have revealed how expansion history, dispersal mechanisms and environmental barriers modulate genomic signatures. Theoretical models and simulations provide quantitative frameworks to predict allele‐frequency spectra under different dispersal kernels and carrying capacities. This body of research has global significance for understanding biological invasions, conservation of fragmented populations under climate change and management of pest species. Integration of high-throughput genomic data with spatially explicit sampling now allows reconstruction of colonisation routes and identification of loci under selection, underpinning applications that range from preventing spread of invasive taxa to conserving genetic resilience in shifting populations.

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Genetic Dynamics of Range Expansion publication trend

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Technical terms

Genetic drift: Random fluctuations in allele frequencies due to sampling effects in finite populations.

Founder event: Establishment of a new population by a small number of individuals carrying only a subset of the genetic variation.

Allele frequency spectrum: Distribution of allele frequencies across loci used to infer demographic history.

Heterozygosity: Proportion of individuals in a population that are heterozygous at a given locus, indicating genetic diversity.

Expansion load: Accumulation of deleterious mutations at the expanding front due to reduced selection efficiency.

Directionality index (ψ): Statistic summarising asymmetries in allele frequencies to detect the direction of range expansions.

References

1. Boundary Effects Cause False Signals of Range Expansions in Population Genomic Data. Molecular Biology and Evolution (2024).
2. Evolution is more repeatable in the introduction than range expansion phase of colonization. Evolution Letters (2023).
3. Population genetics of a recent range expansion and subsequent loss of migration in monarch butterflies. Molecular Ecology (2022).