Host population bottlenecks drive parasite extinction during antagonistic coevolution

Area of Science:

• Evolutionary biology
• Microbial ecology
• Population dynamics

Background:

• Host-parasite dynamics are crucial in ecology and evolution.
• Large fluctuations in host populations (bottlenecks) can significantly impact coevolutionary trajectories.
• Previous theoretical models suggested bottlenecks favor parasites.

Purpose of the Study:

• To investigate the impact of host population bottlenecks on bacterial-phage coevolution.
• To understand how ecological factors influence evolutionary dynamics.

Main Methods:

• Co-evolutionary experiments involving bacteria and bacteriophages.
• Manipulation of host population size to create genetic bottlenecks.
• Analysis of phage extinction and bacterial population dynamics.

Main Results:

• Contrary to theory, phages were rapidly driven to extinction under bottleneck conditions.
• Stochastic loss of susceptible bacteria, essential for phage infectivity, caused phage extinction.
• Ecological feedbacks between host population size and coevolutionary dynamics were observed.

Conclusions:

• Host population bottlenecks can lead to parasite extinction, challenging existing theory.
• The interplay between ecological dynamics and coevolution is critical for understanding host-parasite systems.
• Findings highlight the importance of considering ecological context in evolutionary studies.