Functional bottlenecks can emerge from non-epistatic underlying traits

Fuente: arXiv
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Auteurs principaux: Schulte, Anna Ottavia, Alqatari, Samar, Rossi, Saverio, Zamponi, Francesco
Format: Preprint
Publié: 2025
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author Schulte, Anna Ottavia
Alqatari, Samar
Rossi, Saverio
Zamponi, Francesco
author_facet Schulte, Anna Ottavia
Alqatari, Samar
Rossi, Saverio
Zamponi, Francesco
contents Protein fitness landscapes frequently exhibit epistasis, where the effect of a mutation depends on the genetic context in which it occurs, i.e., the rest of the protein sequence. Epistasis increases landscape complexity, often resulting in multiple fitness peaks. In its simplest form, known as global epistasis, fitness is modeled as a non-linear function of an underlying additive trait. In contrast, more complex epistasis arises from a network of (pairwise or many-body) interactions between residues, which cannot be removed by a single non-linear transformation. Recent studies have explored how global and network epistasis contribute to the emergence of functional bottlenecks - fitness landscape topologies where two broad high-fitness basins, representing distinct phenotypes, are separated by a bottleneck that can only be crossed via one or a few mutational paths. Here, we introduce and analyze a stylized model of global epistasis with an additive underlying trait. We demonstrate that functional bottlenecks arise with high probability if the model is properly calibrated. Furthermore, our results underscore that a proper balance between neutral and non-neutral mutations is needed for the emergence of functional bottlenecks.
format Preprint
id arxiv_https___arxiv_org_abs_2505_14166
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Functional bottlenecks can emerge from non-epistatic underlying traits
Schulte, Anna Ottavia
Alqatari, Samar
Rossi, Saverio
Zamponi, Francesco
Populations and Evolution
Disordered Systems and Neural Networks
Statistical Mechanics
Biomolecules
Protein fitness landscapes frequently exhibit epistasis, where the effect of a mutation depends on the genetic context in which it occurs, i.e., the rest of the protein sequence. Epistasis increases landscape complexity, often resulting in multiple fitness peaks. In its simplest form, known as global epistasis, fitness is modeled as a non-linear function of an underlying additive trait. In contrast, more complex epistasis arises from a network of (pairwise or many-body) interactions between residues, which cannot be removed by a single non-linear transformation. Recent studies have explored how global and network epistasis contribute to the emergence of functional bottlenecks - fitness landscape topologies where two broad high-fitness basins, representing distinct phenotypes, are separated by a bottleneck that can only be crossed via one or a few mutational paths. Here, we introduce and analyze a stylized model of global epistasis with an additive underlying trait. We demonstrate that functional bottlenecks arise with high probability if the model is properly calibrated. Furthermore, our results underscore that a proper balance between neutral and non-neutral mutations is needed for the emergence of functional bottlenecks.
title Functional bottlenecks can emerge from non-epistatic underlying traits
topic Populations and Evolution
Disordered Systems and Neural Networks
Statistical Mechanics
Biomolecules
url https://arxiv.org/abs/2505.14166