No abstract

Despite their ubiquity, in most cases little is known about the impact of eukaryotic parasites on their mammalian hosts. Comparative approaches provide a powerful method to investigate the impact of parasites on host ecology and evolution, though two issues are critical for such efforts: controlling for variation in methods of identifying parasites and incorporating heterogeneity in sampling effort across host species. To address these issues, there is a need for standardized methods to catalogue eukaryotic parasite diversity across broad phylogenetic host ranges. We demonstrate the feasibility of a metabarcoding approach for describing parasite communities by analysing faecal samples from 11 nonhuman primate species representing divergent lineages of the primate phylogeny and the full range of sampling effort (i.e. from no parasites reported in the literature to the best‐studied primates). We detected a number of parasite families and regardless of prior sampling effort, metabarcoding of only ten faecal samples identified parasite families previously undescribed in each host (x̅ = 8.5 new families per species). We found more overlap between parasite families detected with metabarcoding and published literature when more research effort—measured as the number of publications—had been conducted on the host species' parasites. More closely related primates and those from the same continent had more similar parasite communities, highlighting the biological relevance of sampling even a small number of hosts. Collectively, results demonstrate that metabarcoding methods are sensitive and powerful enough to standardize studies of eukaryotic parasite communities across host species, providing essential new tools for macroecological studies of parasitism.

Increased risk of infectious disease transmission has been proposed as one major cost of group living. While factors corresponding to transmission via exposure to infectious stages and susceptibility to contracting infections upon contact are relatively well understood, both aspects are rarely investigated simultaneously. Here, we assessed the influence of exposure and susceptibility measures on strongyle nematode reinfection after experimental deworming of Barbary macaques (Macaca sylvanus) (n = 57). We investigated impacts of behaviour (social bonds, grooming and ground use) and physiology (faecal glucocorticoids, urinary C‐Peptides, urinary neopterin, gastrointestinal [GI] helminth coinfection) on the likelihood of reinfection, using patch occupancy modelling and information theoretic model selection to determine the best models predicting reinfection patterns. Coinfection was the most consistent risk factor, spending time on presumably contaminated soil, interacting with many partners and forming strong same‐sex bonds also tended to increase infection risk. In contrast, strong social bonds with opposite‐sex partners had a consistently protective effect. Our results indicate that coinfections could serve as an integrative measure of individual disease susceptibility. Furthermore, we show that social contact contributes to both exposure and susceptibility to environmentally transmitted parasites, with the outcome depending on specific interaction patterns. A plain language summary is available for this article.