Lytic and temperate phage naturally coexist in a dynamic population model

Area of Science:

• Microbiology
• Ecology
• Evolutionary Biology

Background:

• Bacteriophages (phage) exhibit two main life cycles: lysis (cell destruction) and lysogeny (genome integration).
• Optimal phage strategies are assumed to be environment-dependent, yet diverse strategies coexist in nature.
• The coexistence of phage with different lysis/lysogeny strategies despite apparent differences in optimality presents an ecological puzzle.

Purpose of the Study:

• To investigate the mechanisms enabling the coexistence of bacteriophages with distinct lysis/lysogeny strategies within the same environment.
• To explore the population dynamics of phage communities and their lysogens.

Main Methods:

• Utilized a mathematical modeling framework to simulate population dynamics.
• Modeled communities comprising phage with varying lysis/lysogeny strategies and their bacterial hosts (lysogens).

Main Results:

• Coexistence of phage with different lysis/lysogeny strategies is a natural outcome of chaotic population dynamics in diverse communities.
• Sufficient community diversity prevents any single phage strategy from achieving absolute competitive dominance.
• Obligate lytic (virulent) phage strains tend to outcompete temperate phage strains but are also more prone to local extinction.

Conclusions:

• Chaotic dynamics in diverse phage communities facilitate the coexistence of multiple lysis/lysogeny strategies.
• Phage pan-genome bet-hedging, where different strategies confer resilience, is a key factor in maintaining diversity.
• Environmental conditions and community structure play crucial roles in shaping phage population dynamics and evolutionary trajectories.