Hot spots become cold spots: coevolution in variable temperature environments

Area of Science:

• Evolutionary Biology
• Ecology
• Microbiology

Background:

• Antagonistic coevolution between hosts and parasites drives biological diversity.
• Environmental conditions significantly influence coevolutionary dynamics.
• The impact of variable environments on coevolution remains understudied.

Purpose of the Study:

• To investigate how fluctuating environments affect antagonistic coevolution.
• To determine the role of temperature variation in host-parasite coevolutionary dynamics.

Main Methods:

• Experimental evolution using microcosms of Pseudomonas fluorescens SBW25 and lytic phage SBWΦ2.
• Manipulation of temperature fluctuation frequencies to simulate variable environmental conditions.
• Monitoring of population densities and coevolutionary trajectories.

Main Results:

• High-frequency temperature fluctuations did not alter typical coevolutionary arms race patterns.
• Intermediate- and low-frequency fluctuations led to stalled coevolution during high-temperature periods, creating 'coevolutionary cold spots'.
• Temperature variation impacted population densities, suggesting eco-evolutionary feedbacks via encounter rates.

Conclusions:

• Environmental fluctuations can induce temporary cessations in antagonistic coevolution.
• The frequency of environmental change is critical in determining whether coevolution persists or stalls.
• Coevolutionary outcomes are contingent on the interplay between environmental variability and species' environmental optima.