Data from: Of poisons and parasites: the defensive role of tetrodotoxin against infections in newts

1. Classical research on animal toxicity has focused on the role of toxins
in protection against predators, but recent studies suggest these same
compounds can offer a powerful defense against parasites and infectious
diseases. 2. Newts in the genus Taricha are brightly colored and contain
the potent neurotoxin, tetrodotoxin (TTX), which is hypothesized to have
evolved as a defense against vertebrate predators such as garter snakes.
However, newt populations often vary dramatically in toxicity, which is
only partially explained by predation pressure. 3. The primary aim of this
study was to evaluate the relationships between individual-level TTX
concentration and infection by parasites. By systematically assessing
micro- and macroparasite infections among 345 adult newts (sympatric
populations of Taricha granulosa and T. torosa), we detected 18 unique
taxa of helminths, fungi, viruses, and protozoans. 4. For both newt
species, per-host concentrations of TTX, which varied from undetectable to
>60 µg cm-2 skin, negatively predicted overall parasite richness as
well as the likelihood of infection by the chytrid fungus,
Batrachochytrium dendrobatidis, and ranavirus. No such effect was found on
infection load among infected hosts. Despite commonly occurring at the
same wetlands, T. torosa supported higher parasite richness and average
infection load than T. granulosa. Host body size and sex (females >
males) tended to positively predict infection levels in both species. For
hosts in which we quantified leukocyte profiles, total white blood cell
count correlated positively with both parasite richness and total
infection load. 5. By coupling data on host toxicity and infection by a
broad range of micro- and macroparasites, these results suggest that –
alongside its effects on predators – tetrodotoxin may help protect newts
against parasitic infections, highlighting the importance of integrative
research on animal chemistry, immunological defenses, and natural enemy
ecology.