Epistasis and Genetic Variance in Natural Populations
Summary
Epistasis arises when alleles at one locus modify the phenotypic expression of alleles at another, generating non-additive contributions to trait variation. In natural populations, genetic variance for quantitative characters is decomposed into additive, dominance and epistatic components. Although classical theory emphasises additive genetic variance as the principal driver of evolutionary response, mounting evidence indicates that interactions among loci shape both the magnitude and the additive component of genetic variance itself. Epistatic interactions can mask or reveal genetic variation, thus influencing the realised heritability of fitness-related traits and the capacity of populations to respond to selection. Empirical studies using quantitative trait locus mapping, genome-wide association and breeding experiments reveal that epistasis often underlies complex traits such as life-history attributes, morphological features and behavioural tendencies. By modulating the additive variance, epistatic networks can either facilitate rapid adaptation under novel environments or constrain evolution by creating rugged fitness landscapes. In geographically structured populations and admixed lineages, epistasis may further interact with demographic history to generate patterns of standing variation and adaptive potential. The interplay between epistatic architecture and environmental heterogeneity carries profound implications for biodiversity conservation, crop and livestock improvement, and the management of emerging diseases. Contemporary approaches integrating high-throughput sequencing, statistical genetics and experimental crosses are transforming our understanding of how gene-gene interactions contribute to the evolutionary dynamics of natural populations.
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Epistasis and Genetic Variance in Natural Populations publication trend
The graph below shows the total number of articles in epistasis and genetic variance in natural populations across all publications each year (not limited to Nature Index journals).
Technical terms
Epistasis: Interaction between alleles at different loci such that their combined phenotypic effect deviates from the sum of individual effects.
Additive genetic variance: Component of genetic variance attributable to the average, heritable effects of individual alleles, governing the predictable response to selection.
Quantitative trait locus (QTL): Genomic region harbouring one or more genes contributing statistically to variation in a quantitative trait.
Genetic architecture: The number, effect sizes and interaction patterns of loci underlying phenotypic variation in a trait.
References
- The other 96%: Can neglected sources of fitness variation offer new insights into adaptation to global change?. Evolutionary Applications (2016).
- Epistasis Is a Major Determinant of the Additive Genetic Variance in Mimulus guttatus. PLOS Genetics (2015).
- The Origin of Additive Genetic Variance Driven by Positive Selection. Molecular Biology and Evolution (2020).
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