Dealing with incongruence in phylogenomic analyses.

Area of Science:

• Evolutionary Biology
• Genomics
• Bioinformatics

Background:

• Gene tree incongruence is a major challenge in modern phylogenetics, particularly in the genomic era.
• This incongruence can arise from methodological artifacts or genuine biological processes like horizontal gene transfer (HGT).
• Horizontal gene transfers significantly impact bacterial genome evolution, leading to phylogenetic conflicts.

Purpose of the Study:

• To assert the continued scientific validity and reconstructibility of the bacterial species tree despite prevalent HGTs.
• To quantify the extent of phylogenetic incongruence attributable to HGTs in bacterial datasets.
• To review and assess phylogenomic methods for their capacity to discern vertical and horizontal evolutionary signals.

Main Methods:

• Comparative analysis of bacterial genomic datasets against a metazoan dataset (assumed to have minimal HGTs) to estimate incongruence levels.
• Review of existing phylogenomic methodologies.
• Evaluation of methods for their ability to resolve both vertical (speciation) and horizontal (gene transfer) evolutionary histories.

Main Results:

• Horizontal gene transfers (HGTs) are a significant source of phylogenetic incongruence in bacterial genomes.
• The bacterial species tree remains a meaningful concept and a valid target for reconstruction, even with substantial HGTs.
• Existing phylogenomic methods vary in their effectiveness at disentangling vertical and horizontal evolutionary signals.

Conclusions:

• Reconstructing the bacterial species tree is a feasible and important goal, despite the complexities introduced by HGTs.
• Understanding the balance between vertical inheritance and HGT is crucial for accurate bacterial evolutionary studies.
• Further development and application of phylogenomic methods are needed to fully resolve complex evolutionary histories shaped by gene transfer events.