Interspecific interactions among parasites in multiple infections.

Multiple infections comprising different parasite species in the same host and/or population are common. It is important to understand the relative importance of intraspecific versus interspecific multiple infections. Being explicit about interspecific interactions allows understanding the maintenance of coinfections using ecological theory of community assembly. Reproductive interference is an overlooked process in interspecific coinfections but can determine the competitive outcomes between parasites. Coinfection enables sharing genetic material among species but the consequences thereof remain unclear. Phylogenetic distances between parasites may be a key determinant in understanding the role of interspecific interactions for the maintenance of coinfection. Individual hosts and populations frequently harbour multiple parasite species simultaneously. Despite their commonness, the consequences of interspecific interactions among parasites for determining infection outcomes are still poorly understood. We review and propose several expectations for multiple infections involving different species. We highlight that interspecific interactions affect the outcome of competition within hosts and that heterospecific parasites engage in cotransmission, gene exchange, and reproductive interference. Studies specifically comparing intra- and inter-specific coinfections and knowledge from community ecology may be instrumental to fully understand the consequences of interspecific multiple infections for parasite life history, ecology, and evolution. [ABSTRACT FROM AUTHOR]