# Effect of resistant compartment on pathogen strategy in partially migratory populations

## TL;DR

This study shows that when animals spend more time in a resistant state, more harmful pathogens can evolve, affecting migratory populations.

## Contribution

The study introduces a new SIRS model to show how a resistant compartment influences pathogen virulence evolution.

## Key findings

- A longer time in the resistant compartment leads to the evolution of more virulent pathogens.
- Pathogen strategy is influenced by recovery and immunity loss rates in partially migratory populations.

## Abstract

Migration, the recurring movement of animals between habitats, can exert pressures on the pathogens they host. Properties of host populations can determine pathogen strategy (e.g. virulence) to increase pathogen fitness. To study the effect of adding a resistant compartment on virulence evolution, we developed an SIRS model and examined the winning pathogen strategy across different rates of recovery and of immunity loss. We find that when hosts spend a relatively long time in the resistant compartment, a more virulent pathogen evolves. These results have implications in conservation of migratory animal populations afflicted by disease.