Algorithms to reconstruct past indels: The deletion-only parsimony problem.

Ancestral sequence reconstruction is an important task in bioinformatics, with applications ranging from protein engineering to the study of genome evolution. When sequences can only undergo substitutions, optimal reconstructions can be efficiently computed using well-known algorithms. However, acco...

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Main Authors: Jordan Moutet, Eric Rivals, Fabio Pardi
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2025-07-01
Series:PLoS Computational Biology
Online Access:https://doi.org/10.1371/journal.pcbi.1012585
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author Jordan Moutet
Eric Rivals
Fabio Pardi
author_facet Jordan Moutet
Eric Rivals
Fabio Pardi
author_sort Jordan Moutet
collection DOAJ
description Ancestral sequence reconstruction is an important task in bioinformatics, with applications ranging from protein engineering to the study of genome evolution. When sequences can only undergo substitutions, optimal reconstructions can be efficiently computed using well-known algorithms. However, accounting for indels in ancestral reconstructions is much harder. First, for biologically-relevant problem formulations, no polynomial-time exact algorithms are available. Second, multiple reconstructions are often equally parsimonious or likely, making it crucial to correctly display uncertainty in the results. Here, we consider a parsimony approach where only deletions are allowed, while addressing the aforementioned limitations. First, we describe an exact algorithm to obtain all the optimal solutions. The algorithm runs in polynomial time if only one solution is sought. Second, we show that all possible optimal reconstructions for a fixed node can be represented using a graph computable in polynomial time. While previous studies have proposed graph-based representations of ancestral reconstructions, this result is the first to offer a solid mathematical justification for this approach. Finally we provide arguments for the relevance of the deletion-only case for the general case.
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institution Kabale University
issn 1553-734X
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language English
publishDate 2025-07-01
publisher Public Library of Science (PLoS)
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spelling doaj-art-30ce373fe74442f6b47d9f92d2b35a332025-08-23T05:31:12ZengPublic Library of Science (PLoS)PLoS Computational Biology1553-734X1553-73582025-07-01217e101258510.1371/journal.pcbi.1012585Algorithms to reconstruct past indels: The deletion-only parsimony problem.Jordan MoutetEric RivalsFabio PardiAncestral sequence reconstruction is an important task in bioinformatics, with applications ranging from protein engineering to the study of genome evolution. When sequences can only undergo substitutions, optimal reconstructions can be efficiently computed using well-known algorithms. However, accounting for indels in ancestral reconstructions is much harder. First, for biologically-relevant problem formulations, no polynomial-time exact algorithms are available. Second, multiple reconstructions are often equally parsimonious or likely, making it crucial to correctly display uncertainty in the results. Here, we consider a parsimony approach where only deletions are allowed, while addressing the aforementioned limitations. First, we describe an exact algorithm to obtain all the optimal solutions. The algorithm runs in polynomial time if only one solution is sought. Second, we show that all possible optimal reconstructions for a fixed node can be represented using a graph computable in polynomial time. While previous studies have proposed graph-based representations of ancestral reconstructions, this result is the first to offer a solid mathematical justification for this approach. Finally we provide arguments for the relevance of the deletion-only case for the general case.https://doi.org/10.1371/journal.pcbi.1012585
spellingShingle Jordan Moutet
Eric Rivals
Fabio Pardi
Algorithms to reconstruct past indels: The deletion-only parsimony problem.
PLoS Computational Biology
title Algorithms to reconstruct past indels: The deletion-only parsimony problem.
title_full Algorithms to reconstruct past indels: The deletion-only parsimony problem.
title_fullStr Algorithms to reconstruct past indels: The deletion-only parsimony problem.
title_full_unstemmed Algorithms to reconstruct past indels: The deletion-only parsimony problem.
title_short Algorithms to reconstruct past indels: The deletion-only parsimony problem.
title_sort algorithms to reconstruct past indels the deletion only parsimony problem
url https://doi.org/10.1371/journal.pcbi.1012585
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AT ericrivals algorithmstoreconstructpastindelsthedeletiononlyparsimonyproblem
AT fabiopardi algorithmstoreconstructpastindelsthedeletiononlyparsimonyproblem