Summary of literature survey
Our final data set included 98 studies and 893 effects (Fig. 1). While most studies reported the results from a single experiment, 21 studies included between two and four experiments, resulting in a total of 122 experiments. Host taxa included arthropods (n = 20 species), molluscs (n = 13 species), fish (n = 13 species), amphibians (n = 21 species), and a few other vertebrates (two bird species, one reptile, and one mammal). Parasite taxa comprised viruses (n = 37), bacteria (n = 14), fungi (n = 6), parasitic animals (n = 13), and other eukaryotes (n = 8).