Dominance and multi-locus interaction

TL;DR

This paper reviews how dominance varies across genetic backgrounds and how multi-locus interactions influence phenotypic expression, emphasizing the importance of integrating epistasis and dominance for understanding evolution.

Contribution

It provides a comprehensive review of empirical evidence for variable dominance and discusses models that incorporate epistasis and dominance in evolutionary processes.

Findings

Empirical evidence shows dominance varies with genetic background.

Epistatic models can capture observed dominance variability.

Integrating epistasis and dominance is key to understanding adaptation.

Abstract

Dominance is usually considered a constant value that describes the relative difference in fitness or phenotype between heterozygotes and the average of homozygotes at a focal polymorphic locus. However, the observed dominance can vary with the genetic background of the focal locus. Here, alleles at other loci modify the observed phenotype through position effects or dominance modifiers that are sometimes associated with pathogen resistance, lineage, sex, or mating type. Theoretical models have illustrated how variable dominance appears in the context of multi-locus interaction (epistasis). Here, we review empirical evidence for variable dominance and how the observed patterns may be captured by proposed epistatic models. We highlight how integrating epistasis and dominance is crucial for comprehensively understanding adaptation and speciation.