The complexity hypothesis revisited: connectivity rather than function constitutes a barrier to horizontal gene...

Area of Science:

• Evolutionary biology
• Microbial genomics
• Molecular evolution

Background:

• Horizontal gene transfer (HGT) significantly impacts microbial evolution and adaptation.
• Gene transferability is influenced by cellular processes and gene connectivity, forming the basis of the 'Complexity Hypothesis'.
• Previous studies suggest a correlation between gene function, protein-protein interaction network connectivity, and HGT success.

Purpose of the Study:

• To disentangle the relative contributions of biological function and protein connectivity to gene transferability.
• To quantify the impact of these factors on the success of horizontal gene transfer events.
• To provide novel insights into the 'Complexity Hypothesis' governing gene transferability.

Main Methods:

• Utilized a stochastic mapping method with advanced likelihood-based evolutionary models.
• Applied methodology to an extensive, across-species, genome-wide dataset.
• Quantified gene family acquisition events attributed to HGT.

Main Results:

• Biological function is an insignificant factor in gene transferability when protein connectivity is similar.
• Gene connectivity is a significant factor determining transferability, even when biological functions are comparable.
• Connectivity emerged as a more critical determinant of gene transferability than cellular function.

Conclusions:

• Gene connectivity plays a more dominant role in determining horizontal gene transfer success than biological function.
• The 'Complexity Hypothesis' requires refinement, emphasizing connectivity over function in HGT.
• This research provides a quantitative framework for understanding barriers and trends in gene transferability.