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Pace of life, predators and parasites: predator-induced life-history evolution in Trinidadian guppies predicts
J F Stephenson1, C van Oosterhout2, J Cable3
1School of Biosciences, Cardiff University, Cardiff, UK jfrstephenson@gmail.com.
Biology Letters
|November 6, 2015
Summary
Predation pressure drives faster life histories in guppies, leading to reduced parasite defense. This study reveals lower-body condition in infected guppies from high-predation areas, supporting the pace of life hypothesis.
Area of Science:
- Evolutionary biology
- Ecology
- Parasitology
Background:
- Predation pressure often drives evolutionary shifts towards faster life histories.
- The pace of life hypothesis posits that short-lived organisms invest less in parasite defense.
- Combining these ideas predicts that high-predation populations within a species may show reduced parasite defense.
Purpose of the Study:
- To test the prediction that populations experiencing higher predation pressure invest less in parasite defense.
- To investigate the relationship between predation, life history, and parasite tolerance in Trinidadian guppies (Poecilia reticulata).
Main Methods:
- Conducted a large-scale field survey of Trinidadian guppy populations.
- Compared body condition (scaled mass index) of parasite-infected and uninfected fish across river courses with differing predation pressures.
Main Results:
- Fish infected with Gyrodactylus parasites exhibited lower body condition than uninfected fish, but only in lower-course (high-predation) populations.
- Upper-course guppies (lower predation) showed less fitness cost from parasite infection, indicating higher tolerance.
- Data are correlational but consistent with the pace of life hypothesis.
Conclusions:
- Life-history traits appear to mediate the indirect effects of predators on prey parasites.
- Predator-prey interactions can influence host-parasite dynamics through evolved host life-history strategies.
- Trinidadian guppies demonstrate how predation shapes investment in parasite defense and tolerance.
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