Weakest link epistasis and the geometry of genetic load.

ABSTRACT: Because natural selection must optimise multiple traits at once, previous work has suggested that phenotypic dimensionality can substantially worsen the equilibrium fitness defect of a population relative to the phenotypic optimum. However, it remains unclear how conclusions drawn from classical theoretical phenotype-fitness maps extend to models grounded in explicit biological mechanisms. Here we introduce weakest-link epistasis (WLE), a framework in which fitness is determined by the least-fit phenotypic component, an extreme form of diminishing returns epistasis. We show that in this framework, increasing dimensionality amplifies the load in a manner comparable to, but surprisingly not more than, Fisher's geometric model (FGM). Building on this similarity, we demonstrate why genetic loa

SUBMITTER: Labourel FJF 

PROVIDER: S-EPMC12822725 | biostudies-literature | 2026 Jan

REPOSITORIES: biostudies-literature