Pathogens stabilize or destabilize depending on host stage structure

Area of Science:

• Ecology
• Epidemiology
• Theoretical Biology

Background:

• Pathogens are often assumed to destabilize host populations, impacting conservation and management strategies.
• Population stability is influenced by environmental factors and host-pathogen traits, especially in size- and stage-structured populations.

Purpose of the Study:

• To investigate how pathogens affect host population stability within size- and stage-structured consumer-resource models.
• To explore the context-dependent interplay between host population structure, resource competition, and infectious disease dynamics.

Main Methods:

• Integration of a size- and stage-structured consumer-resource model with a standard epidemiological model for directly transmitted pathogens.
• Mathematical modeling to analyze population dynamics under varying ecological and epidemiological parameters.

Main Results:

• The model demonstrated complex dynamics, including sustained oscillations, multiple stable states, biomass overcompensation, and the 'hydra effect'.
• Host population structure and density were found to significantly influence the likelihood and severity of disease outbreaks.
• Bidirectional feedbacks between host population structure and disease dynamics were identified.

Conclusions:

• Pathogen effects on host population stability are context-dependent and modulated by population structure.
• Understanding these complex interactions is crucial for effective ecosystem management and disease control strategies.
• Accounting for cross-scale feedbacks between host populations and pathogens offers key insights into ecological structuring and intervention impacts.