Total parasite richness in relation to distance from freshwater. Satellites (orange fill) increased in abundance near the shore, while core parasites (maroon line) were steady. Total parasite richness (orange line) in relation to distance from shore. There were actually fewer core parasites but more satellite parasites near the freshwater ecotone (right graph below). Overall, parasite richness was relatively constant in relation to distance from the freshwater ecotone. The story was very different for the freshwater ecotone. Racoons nearer to the marine ecotone harbored more parasite species than did raccoons more distant from the marine ecotone, a result of much greater richness of satellite species (left graph below). In Santa Barbara County, Weinstein and her colleagues identified four core parasites and nine satellite parasites within the population, with a mean of 2.24 parasite species per raccoon. In contrast, satellite parasites should increase in ecotones, because ecotones provide unique environmental conditions that would be suitable to some of the less common species in the parasite community. They hypothesized that the prevalence of core parasites should not be overly affected by ecotones. Having defined core and satellite parasites, the researchers then did a thorough analysis of the gut contents of 180 raccoon collected by trappers and animal control agents in Santa Barbara County between 2012 – 2015. The eight common taxa – core parasites – also tended to be present in more individuals within each population than did the 51 less common genera of satellite parasites (bottom graph on left). In contrast there were 51 genera that were found in fewer than 30% of raccoon populations, with the vast majority of these found in fewer than 10% of raccoon populations in the survey (top graph on left). There were eight taxa (genera) that were found in more than 40% of raccoon populations. Larger data points indicate more populations surveyed for a given parasite. Proportion of raccoons infected with each parasite in relation to range-wide prevalence. Dashed line indicates 30% cutoff between satellite and core genera. Most parasite genera were found in less than 10% of the raccoon populations. Parasite frequency across raccoon populations.
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