Multiyear Time-Shift Study of Bacteria and Phage Dynamics in the Phyllosphere

Area of Science:

• Ecology
• Evolutionary Biology
• Microbial Ecology

Background:

• Coevolution drives biodiversity but is challenging to study directly.
• Time-shift experiments are valuable for measuring coevolutionary change and testing models.
• Previous studies indicated an asymmetry in host-parasite interactions over time.

Purpose of the Study:

• To extend the time window of previous time-shift experiments.
• To confirm the observed asymmetry in host-parasite interactions over longer timescales.
• To investigate the implications of asymmetric coevolution for theoretical models.

Main Methods:

• Utilized time-shift experiments with natural microbial communities from horse chestnut tree leaves.
• Extended the observation period across multiple years to assess long-term coevolutionary dynamics.
• Quantified bacterial host resistance and bacteriophage infectivity across different time points.

Main Results:

• Confirmed the previously observed asymmetry in coevolution over extended time periods.
• Bacterial hosts demonstrated increased resistance to bacteriophages from earlier time points.
• Bacteriophages exhibited highest infectivity against contemporary bacterial hosts.

Conclusions:

• The study confirms asymmetric coevolutionary dynamics between bacterial hosts and bacteriophages.
• Findings suggest a need to revise existing coevolutionary theory to account for differing host-parasite models.
• Asymmetric coevolution may significantly alter predicted evolutionary outcomes.