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Biodiversity loss decreases parasite diversity: theory and patterns
1Western Ecological Research Center, US Geological Survey, c/o Marine Science Institute, University of California, Santa Barbara, CA 93106, USA. lafferty@lifesci.ucsb.edu
Summary
Biodiversity loss significantly impacts parasite diversity, with extinction order and host specificity playing key roles. Parasite richness declines more steeply than previously modeled, especially in complex food webs.
Area of Science:
- Ecology
- Parasitology
- Biodiversity Science
Background:
- Previous models predicted linear or concave-down relationships between free-living species richness and parasite richness due to host-parasite coextinction.
- Factors like host specificity, parasite life cycle complexity, and food web structure can influence these relationships.
Purpose of the Study:
- To explore various models predicting the relationship between parasite richness and biodiversity loss.
- To investigate how factors like food web complexity and extinction order affect host-parasite coextinction dynamics.
Main Methods:
- Simulated food web disassemblies to model extinction trajectories of parasites.
- Analyzed the impact of host specificity, parasite life cycle complexity, and host position in the food chain.
- Examined empirical food webs with random removals of free-living species.
Main Results:
- Parasite species' robustness to free-living species loss is reduced by complex life cycles, low parasite generality, and host sensitivity.
- Food web complexity and the order of extinctions create unique, often unpredictable, relationships between parasite and free-living species richness.
- Parasites of specialist hosts and those higher in food chains are more prone to extinction.
- Correlated extinctions between hosts and parasites can accelerate parasite richness decline.
- Empirical data with random species removals showed a quasi-linear decline in parasite richness, indicating a greater impact of biodiversity loss than previously assumed.
Conclusions:
- Biodiversity loss leads to a more substantial reduction in parasite diversity than suggested by simpler models.
- The sequence of species extinctions and ecological interactions significantly shapes the coextinction process.
- Understanding these complex dynamics is crucial for accurate biodiversity conservation strategies.
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