How and why to quantify pairwise pleiotropy and genotype-by-environment interactions

Ellis, T. J.

doi:10.64898/2026.01.09.698568

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How and why to quantify pairwise pleiotropy and genotype-by-environment interactions

Ellis, T. J.

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Abstract

Pleiotropy is when a single locus affects two or more traits. The magnitude and direction of pleiotropy can constrain or faciliate phenotypic evolution. Investigations of pleiotropy have typically relied on null-hypothesis tests to classify cases into discrete categories based on the direction of effects. This discrete approach ignores the quantitative nature of pleiotropy, and systematically underestimates pleiotropic interactions. I describe a simple method to quantify the direction and magnitude of pleiotropic effects to alleviate these issues for pairs of traits. I illustrate how genotype-by-environment interactions can be viewed as a special case of pleiotropy and described in the same way. I provide an R package, psiotropy, to apply these methods.

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Ellis, T. J.. 2026-01-12. How and why to quantify pairwise pleiotropy and genotype-by-environment interactions. https://doi.org/10.64898/2026.01.09.698568

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