Parasites from Fundulus heteroclitus in South Carolina, United States: Are ecological parameters enough to estimate isolation in populations?

Juliana Rosa M. Ciccheto, Emanuel Luis Razzolini,

& Walter Antonio P. Boeger

Eustatic changes can shape the extension of cycles of isolation and connection among neighbor watersheds and their respective animal populations, which may generate diversification through the Taxon Pulse model. Predictions derived from the reconstruction of hydrological paleodrainages indicate that there is no evidence of past connection between populations of freshwater species of the river drainages in the coastal region of South Carolina, United States. In this scenario of continuous isolation, it is interesting to understand the sharing of fish parasites and contact routes between distinct geographic populations. From samples of obtained from three estuarine systems in South Carolina (Baruch, Charleston and Waddell), four species of Gyrodactylidae were identified from the focal fish host, F. heteroclitus. So far, Swingleus sp., Fundulotrema, and two species of Gyrodactylus have been identified. Morphologically, the parasites from different geographic populations did not present any obvious difference. Prevalence, Mean Intensity, and Abundance were compared through the Kruskal-Wallis Analysis of Variance in order to estimate the ecological parameters of the parasitic populations. The abundance of Fundulotrema sp. was significantly distinct among localities, with significant difference for Charleston (p-value= 0.0002552). For Swingleus sp., no significant difference was detected. These are the preliminary results of a project that seeks to answer the influence of sea level variation on the diversification of F. heteroclitus and their parasites in three distinct geographic populations. Although exploratory, the analyzes indicate greater ecological and genetic diversity in Charleston, but they are not enough to confirm the isolation between the focal populations and its consequences. Planned population genetic and phylogeographic analyses may help understand the historical reconstruction of the demography of these species and the association between hosts and parasites, demarcating moments of divergence between populations.