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  • Writer's pictureDave Daversa

Taking a community perspective

A paper I led was published last week. Most of my research looks at parasites in the context of organismal biology, especially organismal behavior. The study described in this paper zoomed out to the context of host communities - the composition of multiple host species sharing space and potentially interacting. Though it diverged from my primary research, the resulting paper is one of my favorites. It is an example of synergies between empirical and theoretical approaches, and the result is cool.

As with most studies, the results were not expected. To the contrary. We formed the experiments around a dominant amphibian species in our focal system, fire salamanders (Salamandra salamandra), and we had evidence that the salamanders were primary carriers of Bd infections in the system. That evidence actually holds up, but one surprise of the experiments was that yearling life stages of salamanders were not highly susceptible to Bd infections like their older, overwintered counterparts. So, an experiment that we thought would show that salamanders were key hosts that both maintained chytrid and spread it to other host species (frogs and toads) instead showed the opposite. Ecology tricked us again.

The paper is a product of teamwork. Trent flaunted his experimentalist power with the experimental design. Jaime did the dirty work with experiments. Andrea used his saavy stats powers to pick out that not only were toads and frogs the key hosts of chytrid in our system but that epidemiologically there acted as nearly identical hosts. Andy’s modelling added nuance. There were subtle differences between frogs and toads – frogs shed more chytrid spores than toads – but those nuances carried no signal at the community scale. Their contributions to R0 were pretty much the same. For chytrid, the identities of salamanders mattered because they were poor hosts. Yet, the identity of frogs versus toads was irrelevant. Host identities mattered, up to a point.

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