Helminth Parasites of Sympatric Salamanders: Ecological Concepts at Infracommunity, Component and Compound Community Levels

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Abstract
Four species assemblages of desmognathine salamanders are sympatric in and along many mountain streams of the southern Appalachians. The species, Leurognathus marmorata, Desmognathus quadramaculatus, D. monticola and D. ochrophaeus, span an aquatic to terrestrial habitat continuum ranging from totally aquatic (L. marmorata) to primarily terrestrial (D. ochrophaeus). Such a system afforded the opportunity of examining concepts of helminth parasite ecology within the context of several recent theoretical predictions. Parasite infracommunities (populations of all helminth species within individual hosts) in salamanders are isolationist in character. That is, parasite prevalence (percentage of hosts infected with a given parasite species) and mean intensity (mean number of parasites of a given species within a species of host) are low, and as a consequence there is little potential for competitive interactions. Isolationist infracommunities in salamanders arise from factors including a simple enteric system, restricted vagility and ectothermic generalist insectivory. Salamanders have a broad prey base and they do not focus on any particular prey species. Transmission of helminths by intermediate hosts is unimportant and contributes to depauperate helminth faunas dominated by nematodes with direct life cycles. The least diverse infracommunities were associated with Leurognathus marmorata while Desmognathus quadramaculatus had the most diverse fauna. Patterns of prevalence and intensity of infection revealed that salamander helminths were, in general, not host specific. Rather, they are generalists and their distributions can be correlated with host size (age), diet and habitat preferences.