Re‐emphasizing mechanism in the community ecology of disease
Kelsey E. Shaw, David J. Civitello
Abstract
Abstract Hosts and their parasites exist within complex ecological communities. However, the role that non‐focal community members, species which cannot be infected by a focal pathogen, may play in altering parasite transmission is often only studied in the lens of the ‘diversity‐disease’ relationship by focusing on species richness. This approach largely ignores mechanistic species interactions and risks collapsing our understanding of the community ecology of disease down to defining the prominence of ‘amplification’ versus ‘dilution’ effects. However, non‐focal species vary in their traits, densities and types of interactions with focal hosts and parasites. Therefore, a community ecology approach based on the mechanisms underlying parasite transmission, host harm and dynamic species interactions may better advance our understanding of parasite transmission in complex communities. Using the concept of the parasite's basic reproductive ratio, R 0 , as a generalizable framework, we examine several critical mechanisms by which interactions among hosts, parasites and non‐focal species modulate transmission and provide examples from relevant literature. By focusing on the mechanism by which non‐focal species impact transmission, we can emphasize the similarities among classic paradigms in the community ecology of disease, gain new insights into parasite invasion and persistence, better predict community traits correlated with disease dilution or amplification, and gauge the feasibility of biocontrol for parasites of conservation, agricultural or human health concern. A free Plain Language Summary can be found within the Supporting Information of this article.