A Blast to the Past: Multi-decadal Trends in Parasite Diversity in Plethodon Salamanders

Samantha O’Keefe, a student at Jacksonville University, worked in the lab of Dr. Sonia Altizer

Abstract Climate change is rapidly impacting our planet and its ecosystems at immense scales, and many of the future impacts are unknown. One consequence of climate change seen in nearly every ecosystem type is loss of biodiversity, including parasitic organisms. To investigate whether parasite communities infecting Plethodon salamanders are changing over time, we utilized formalin fixed natural history collections (mostly Plethodon shermani) collected from Macon County, NC from 1943-2017. Additionally, a collection of surveys of parasites infecting Plethodon salamander species from 1937 was used as a baseline to compare the museum specimens’ sample parasite diversity changes over time. Salamander digestive tracts were surveyed at the 5x magnification using a dissecting scope, and any parasites found were counted and identified to the species level based on morphological traits. We noted that macroparasite aggregation was common, where 80 percent of the parasites were found in 20 percent of the hosts. The findings of this study revealed that the infection prevalence of two parasite taxa were stable, while 4 other gastrointestinal parasite species found were decreasing significantly in prevalence over time, specifically Cosmocercoides dukae, Capillaria inequalis, Crepidobothrium cryptobranci, and an undescribed subcutaneous nematode. These changes in infection prevalence over time may indicate different climate sensitivity between parasite species. Additionally, diversity and parasite richness were found to be gently decreasing, which may indicate overall reduction in parasite transmission. Future directions for this work consists of molecular confirmation of parasite taxa, and the continuation of surveys of preserved salamanders to increase temporal resolution in time chunks.