OG

OG resolves inconsistencies in orthologous group (OG) hierarchies across taxonomic levels by subsampling protein members and using gene tree–species tree reconciliation to produce more reliable hierarchical OG assignments for evolutionary and functional analyses.

Key Features:

• Orthologous group (OG) modeling: Represents OGs as sets of genes sharing a last common ancestor (LCA), including orthologs and paralogs defined relative to speciation events.
• Hierarchical OG linkage: Links broader, temporally distant OGs to more recent, detailed OGs across multiple levels of the tree of life.
• Subsampling of protein space: Performs controlled subsampling within OG members to create manageable subsets for analysis.
• Gene tree–species tree reconciliation per subset: Applies gene tree–species tree reconciliation to each sampled subset to detect and resolve inconsistencies.
• Aggregation of reconciliations: Aggregates multiple reconciliation results to achieve robustness without relying on single large phylogenies.
• Avoidance of large-tree reconciliation: Circumvents the need to construct and reconcile extensive phylogenetic trees by focusing on smaller sampled subsets.
• High-throughput implementation: Implements the methodology as a pipeline suitable for large-scale OG hierarchy inference.
• Application to eggNOG: Methodology has been applied to the eggNOG database to enforce hierarchical consistency across taxonomic levels.
• Independent validation: Validates performance using independent protein domain definitions and reports comparable or superior results to previous methods.

Scientific Applications:

• Consistent OG hierarchy inference: Produces consistent OG hierarchies across taxonomic levels for evolutionary studies.
• Functional annotation improvement: Enhances the reliability of functional annotation by providing consistent OG assignments.
• Phylogenomic analyses: Enables the use of tree reconciliation techniques combined with sampling for constructing reliable OG hierarchies in phylogenomic research.
• Benchmarking of OG methods: Facilitates validation and comparison of OG inference methods using independent protein domain definitions.

Methodology:

Subsampling of protein members within OGs; performing gene tree–species tree reconciliation on each sampled subset; aggregating multiple reconciliation outcomes to resolve hierarchical inconsistencies; implemented as a high-throughput pipeline and validated against independent protein domain definitions.