Host population dynamics in the face of an evolving pathogen

1. Interactions between hosts and pathogens are dynamic at both ecological and evolutionary levels. In the resultant “eco-evolutionary dynamics” ecological and evolutionary processes affect each other. For example, the house finch (Haemorhous mexicanus) and its recently-emerged pathogen, the bacterium Mycoplasma gallisepticum, form a system in which evidence suggests that changes in bacterial virulence through time enhance levels of host immunity in ways that drive the evolution of virulence in an arms race.

2. We use data from two associated citizen science projects in order to determine whether this arms race has had any detectable effect at the population level in the northeastern United States.

3. We used data from two citizen science projects, based on observations of birds at bird feeders, which provide information on the long-term changes in sizes of aggregations of house finches (host population density), and the probabilities that these house finches have observable disea...