Natural History Collections are Needed to Resolve Host Sampling Gaps in Parasitology: Insights from Avian Haemosporidians

The field of parasitology, and thus biodiversity research more broadly, is faced with the unfortunate reality that our understanding of parasite biodiversity can be only as good as our ability to sample parasite host species. Although the sampling of many host species is trivial, there typically remains a subset of species across any host group of interest that is difficult to sample due to rarity, habitat, body size, or some other trait. The result is a blind spot in our understanding of parasite biodiversity that is centered around parasite species that infect hosts that are rarely sampled by humans. However, for many groups of hosts, the daunting task of obtaining host samples has already been done, and these samples exist in the form of natural history collections at institutions across the world. With avian malaria parasites and other haemosporidians as an example, I demonstrate that significant host sampling gaps exist in the United States and Canada. Bird species that have not been sampled for molecular haemosporidian research typically are associated with aquatic habitats, significantly greater masses, and more restricted geographic distributions than are bird species that have already been sampled. These unsampled host species are likely to be infected with a high richness of previously undiscovered avian haemosporidian genetic lineages. However, natural history collections in the United States can be used to nearly completely address these sampling gaps with tissue samples currently housed in these institutions. The result of this analysis indicates that the future of parasite biodiversity research is dependent on the use and support of natural history collections and other biorepositories.