Bacteria-phage interactions across time and space: merging local adaptation and time-shift experiments to understand...

Area of Science:

• Ecology
• Evolutionary Biology
• Microbiology

Background:

• Host-parasite interactions are shaped by local adaptation, where parasites evolve to infect local host populations.
• Reciprocal coevolution predicts parasites will be most effective against past host generations and less effective against future, more resistant hosts.

Purpose of the Study:

• To investigate the temporal dynamics of parasite local adaptation.
• To determine if parasite adaptation to contemporary hosts underestimates the true extent of host-parasite coevolution.

Main Methods:

• Bacteriophages and their bacterial hosts were collected from horse chestnut trees over several months.
• Phage infectivity was compared against bacterial hosts from the same tree and different trees, sampled at different time points.

Main Results:

• Phage adaptation to local bacterial hosts was most pronounced against bacteria from the recent past.
• This indicates that bacterial hosts evolve resistance rapidly, outpacing phage adaptation within the same time frame.

Conclusions:

• Local adaptation studies may underestimate parasite evolution due to the confounding of host and parasite adaptation at contemporary time points.
• Parasite evolution, particularly in conjunction with host responses, occurs rapidly and dynamically over ecological timescales.