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Causation without correlation: parasite-mediated frequency-dependent selection and infection prevalence.
Curtis M Lively1, Julie Xu1, Frida Ben-Ami2
1Department of Biology, Indiana University, Bloomington, 1001 East Third Street, IN 47405, USA.
Biology Letters
|December 21, 2021
Summary
Parasites may maintain host genetic diversity for resistance. However, computer simulations show the link between host diversity and infection prevalence is not always strong, suggesting field studies might underestimate parasite roles.
Area of Science:
- Evolutionary Biology
- Ecology
- Population Genetics
Background:
- Parasite-mediated selection is a key hypothesis for maintaining host genetic diversity.
- A strong positive correlation between host genetic diversity and infection prevalence is often expected in natural populations.
Purpose of the Study:
- To investigate the relationship between host genetic diversity and infection prevalence using computer simulations.
- To examine how parasite virulence and fecundity influence host-parasite coevolution and diversity maintenance.
Main Methods:
- Computer simulations of host-parasite coevolution.
- Modeling of 20 semi-isolated clonal host populations.
- Analysis across a range of parasite virulence and fecundity values.
Main Results:
- A significantly positive correlation between host genetic diversity and infection prevalence was observed under intermediate parasite virulence and fecundity.
- The correlation was weak and non-significant in some scenarios, even when parasites were the sole driver of host diversity.
- Computer simulations revealed complex dynamics not always reflected in simple field correlations.
Conclusions:
- Parasite-mediated selection's role in maintaining host diversity may be underestimated by correlational studies of natural populations.
- The relationship between host genetic diversity and infection prevalence is context-dependent, influenced by parasite traits.
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