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Updated: Jun 26, 2025
08:03
Heuristic Mining of Hierarchical Genotypes and Accessory Genome Loci in Bacterial Populations
Published on: December 7, 2021
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Bacterial lifestyle shapes pangenomes
Anna E Dewar1, Chunhui Hao1, Laurence J Belcher1
1Department of Biology, University of Oxford, Oxford OX1 3SZ, United Kingdom.
Summary
Bacterial pangenome fluidity differs based on lifestyle. Host-associated bacteria exhibit less fluid pangenomes compared to free-living species, challenging the role of effective population size in this variation.
Area of Science:
- Microbiology
- Genomics
- Evolutionary Biology
Background:
- Bacterial pangenomes, the complete set of genes in a species, vary in fluidity (gene diversity) across species.
- Two hypotheses, bacterial lifestyle and effective population size, have been proposed to explain this variation.
- Previous studies struggled to differentiate these factors due to their correlation and phylogenetic conservation.
Purpose of the Study:
- To investigate the causal roles of bacterial lifestyle and effective population size in determining pangenome fluidity.
- To disentangle the relative importance of these factors using advanced phylogenetic analyses.
Main Methods:
- Phylogeny-based analyses were conducted across 126 bacterial species.
- Comparative genomics approaches were used to assess pangenome fluidity.
- Statistical methods were employed to control for phylogenetic relatedness.
Main Results:
- Pangenome fluidity was significantly lower in host-associated bacterial species compared to free-living ones.
- Obligately host-associated, intracellular, pathogenic, and less motile species showed the lowest pangenome fluidity.
- No evidence was found supporting effective population size as a direct driver of pangenome fluidity.
Conclusions:
- Bacterial lifestyle, particularly host association and its associated traits, is a primary determinant of pangenome fluidity.
- Effective population size's correlation with pangenome variation is likely an indirect effect mediated by bacterial lifestyle, not a direct causal relationship.
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