Biology subjects

Fleming-Davies, A. E.

Publications and source records attributed to Fleming-Davies, A. E..

2 recordsLinked to original sources

bioRxiv2024

Wildlife provisioning selects for higher pathogen virulence in hosts with incomplete immunity

Anthropogenic food provisioning provides massive inputs of food to wildlife, with profound ecological and evolutionary consequences. By altering wildlife condition, density, and behavior, provisioning can influence transmission of infectious diseases and thus may impose strong selection pressure on wildlife pathogens. But surprisingly, we lack theory on the eco-evolutionary consequences of provisioning for host-pathogen dynamics. Here we develop a mathematical model of the eco-evolutionary dynamics of a wildlife pathogen under provisioning, motivated by Mycoplasma gallisepticum, a bacterial pathogen that emerged, spread, and changed its virulence in provisioned house finches. We model how provisioning influences the evolution of pathogen virulence, defined here as mortality associated with infection. Consistent with past empirical work, house finches recover from infection and acquire incomplete immunity; this incomplete immunity is stronger if their initial infection was with a more virulent pathogen strain. We find that, even though provisioning improves body condition, it should still select for higher virulence, and thus may actually lead to declines in host populations. These negative effects arise because provisioning magnifies the impact of incomplete immunity, selecting for higher virulence and driving host populations down. Our results highlight that food provisioning can select for more virulent pathogens, with potentially far-reaching implications for conservation.

ecology↗

bioRxiv2024

Prior exposure to pathogens augments host heterogeneity in susceptibility and has key epidemiological consequences

Pathogen epidemics are key threats to human and wildlife health. Across systems, host protection from pathogens following initial exposure is often incomplete, resulting in recurrent epidemics through partially-immune hosts. Variation in population-level protection has important consequences for epidemic dynamics, but how acquired protection influences inter{-}individual heterogeneity in susceptibility and its epidemiological consequences remains understudied. We experimentally investigated whether prior exposure (none, low-dose, or high{-}dose) to a bacterial pathogen alters host heterogeneity in susceptibility among songbirds. Hosts with no prior pathogen exposure had little variation in protection, but heterogeneity in susceptibility was significantly augmented by prior pathogen exposure, with the highest variability detected in hosts given high-dose prior exposure. An epidemiological model parameterized with experimental data found that heterogeneity in susceptibility from prior exposure more than halved epidemic sizes compared with a homogeneous population with identical mean protection. However, because infection-induced mortality was also greatly reduced in hosts with prior pathogen exposure, reductions in epidemic size were smaller than expected in hosts with prior exposure. These results highlight the importance of variable protection from prior exposure and/or vaccination in driving population-level heterogeneity and epidemiological dynamics.

microbiology↗