Related Experiment Video
Updated: May 10, 2026
04:52
Following the Dynamics of Structural Variants in Experimentally Evolved Populations
Published on: February 3, 2023
Temporal dynamics of outcrossing and host mortality rates in host-pathogen experimental coevolution
Levi T Morran1, Raymond C Parrish, Ian A Gelarden
1Department of Biology, Indiana University, Bloomington, IN, USA. lmorran@indiana.edu
Summary
Host mating systems significantly impact coevolutionary outcomes. Outcrossing enhances host-pathogen resistance, promoting population persistence, while selfing can reduce adaptability and increase extinction risk.
Area of Science:
- Evolutionary Biology
- Ecology
- Genetics
Background:
- Antagonistic coevolutionary interactions between hosts and pathogens drive evolutionary arms races.
- Cross-fertilization (outcrossing) is hypothesized to improve host population adaptability and persistence.
- Previous studies indicated obligate selfing hosts face extinction when coevolving with pathogens, unlike outcrossing hosts.
Purpose of the Study:
- To investigate the influence of host mating systems on the dynamics of coevolution with bacterial pathogens.
- To analyze changes in host resistance and pathogen infectivity over time in mixed-mating and obligate outcrossing populations.
- To determine how mating system evolution affects host-pathogen coevolutionary outcomes.
Main Methods:
- Coevolutionary experiments involving Caenorhabditis elegans (host) and Serratia marcescens (pathogen).
- Monitoring host mortality rates and pathogen infectivity across generations.
- Quantifying outcrossing rates within host populations over time.
Main Results:
- Mixed-mating host populations initially experienced increased mortality when outcrossing rates were low, but this decreased as outcrossing evolved.
- Obligate outcrossing host populations showed decreased mortality early in the experiment, remaining low throughout.
- Predominant selfing impaired host response to coevolving pathogens compared to outcrossing.
Conclusions:
- Host mating systems critically influence the pace and outcome of coevolutionary processes.
- Rapid evolutionary changes in host resistance and pathogen infectivity can occur during coevolution.
- The evolution of increased outcrossing can rescue host populations from pathogen-driven decline.
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