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Null expectations for disease dynamics in shrinking habitat: dilution or amplification?
Christina L Faust1,2, Andrew P Dobson3, Nicole Gottdenker4
1Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA christina.faust@glasgow.ac.uk.
Summary
Biodiversity loss from habitat destruction can increase or decrease infectious disease risk. The outcome depends on pathogen transmission type and host body size, challenging the simple dilution effect hypothesis.
Area of Science:
- Ecology
- Epidemiology
- Conservation Biology
Background:
- Anthropogenic land-use change is driving biodiversity loss, raising concerns about infectious disease risk.
- The dilution effect hypothesis suggests reduced biodiversity increases disease risk, offering conservation and health benefits.
- However, empirical evidence for the dilution effect is inconsistent, necessitating further investigation.
Purpose of the Study:
- To investigate how pathogen transmission dynamics respond to biodiversity changes driven by habitat loss.
- To explore the conditions under which declining biodiversity may increase or decrease infectious disease prevalence.
Main Methods:
- Utilized an allometrically scaled multi-host model to simulate pathogen transmission.
- Analyzed the impact of habitat loss on biodiversity and subsequent infectious disease risk (endemic prevalence).
- Examined the influence of pathogen transmission mode (frequency-dependent vs. density-dependent) and host competence scaling with body size.
Main Results:
- Declining biodiversity due to habitat loss can lead to either increased or decreased infectious disease prevalence.
- Dilution effects were observed for most frequency-transmitted pathogens.
- Amplification effects were prominent for density-dependent pathogens and under specific conditions for frequency-dependent pathogens with large-bodied hosts.
Conclusions:
- The relationship between biodiversity and infectious disease risk is complex and context-dependent.
- Pathogen transmission mode and host-competence scaling are critical factors determining whether biodiversity loss amplifies or dilutes disease risk.
- Future research should consider transmission type, host-competence relationships, and host identity in shrinking habitats to understand disease dynamics.
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