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Host-parasite and genotype-by-environment interactions: temperature modifies potential for selection by a sterilizing
Suzanne E Mitchell1, Emily S Rogers, Tom J Little
1University of Edinburgh, School of Biological Sciences, Ashworth Laboratories, The King's Buildings, Edinburgh EH9 3JT, United Kingdom. sue.mitchell@ed.ac.uk
Evolution; International Journal of Organic Evolution
|March 29, 2005
Summary
Environmental temperature significantly influences parasite-mediated selection. Changes in temperature alter bacterial parasite virulence, impacting host genetic diversity and evolutionary outcomes in Daphnia magna.
Area of Science:
- Ecology
- Evolutionary Biology
- Genetics
Background:
- Parasite-mediated selection is a key driver of genetic diversity.
- Genetic variation for host resistance is common, but evolutionary responses are rarely documented.
- Environmental factors can mediate host-parasite interactions and influence selection outcomes.
Purpose of the Study:
- To investigate the role of environmental variation, specifically temperature, in mediating parasite-mediated selection.
- To determine how temperature affects the virulence of the bacterial parasite Pasteuria ramosa on its host, Daphnia magna.
- To assess the impact of temperature-dependent interactions on host genetic diversity and evolutionary trajectories.
Main Methods:
- Conducted two independent laboratory infection experiments using Daphnia magna and Pasteuria ramosa.
- Exposed host-parasite systems to four different temperatures (10°C, 15°C, 20°C, and 25°C).
- Quantified host infection rates, parasite virulence (sterilization), and brood production across temperature treatments.
Main Results:
- Temperature dramatically altered parasite virulence and host-parasite interaction outcomes.
- Pasteuria ramosa exhibited high virulence at 20°C and 25°C, leading to host sterilization.
- At 10°C and 15°C, the interaction was more benign, with most hosts producing broods before sterilization.
- Significant genotype-by-environment interactions were observed, with clone performance varying across temperatures.
Conclusions:
- Environmental temperature is a critical factor mediating parasite-mediated selection.
- Temperature-dependent virulence can stabilize host-parasite coexistence and maintain genetic diversity.
- The evolutionary outcome of parasite-mediated selection is highly context-dependent, influenced by environmental conditions.