Browsing by Author "Schultz, Thomas"

Now showing 1 - 2 of 2

Open Access
Parasite-induced Behavior Modification to the Circatidal Rhythm of the Atlantic Mole Crab, Emerita talpoida
(2017-05-12) Loh, Donovan
Parasites with complex life cycles require transmission from their intermediate host to their definite host to reach sexual maturity. In some parasite-host systems, parasites manipulate the behavior of their intermediate host to enhance transmission to their definitive host. This mode of transmission is termed parasite increased trophic transmission. While there are many examples of parasites inducing atypical behavior in their hosts, little is known about the ability of parasites to modify host biological rhythms. In this study, I examined the effects of parasite load on the strength of host biological rhythms, using the Atlantic mole crab (Emerita talpoida) as a model. Mole crabs are common inhabitants of the swash zone of sandy beaches along the east coast of the United States. They exhibit activity rhythms that are entrained to the tides and act as intermediate hosts for trematode parasites (Microphallus sp.) and acanthocephalan parasites (Profilicollis sp.). For this study, behavioral assays were performed to quantify the strength of the circatidal rhythms of mole crabs before they were dissected to determine parasite load. On average, rhythmic crabs were found to have significantly greater trematode loads but not acanthocephalan loads compared to arrhythmic crabs. This result is further supported by a logistic regression analysis, which revealed trematode load as the most significant predictor of rhythmicity amongst other demographic variables such as size, sex, ovigerity and month of collection. Overall, results from this experiment support the hypothesis that parasites may influence the biological rhythms of their hosts, presenting an additional mechanism through which parasites may enhance trophic transmission.
Open Access
Whole genome scan of regional genetic variation in the common bottlenose dolphin (Tursiops spp.)
(2025-04-17) Wurst, Madison
As anthropogenic activity continues to alter the marine landscape, species including Tursiops truncatus are developing complex population structures. This can be in the formation of ecotypes and populations or differentiation into a new species. The mechanisms and evidence of this formation have recently been a topic of discussion, specifically in the western North Atlantic identifying the inshore ecotype as a distinct species (Tursiops erebennus). However, this conversation of possible speciation stretches beyond the western North Atlantic encompassing almost all Tursiops populations. These discussions focus largely on morphological distinctions and targeted genetic diversity differences. However, in depth, whole genome sequencing (WGS) looking at the genetic differences between the ecotypes/populations could provide a more detailed look at the mechanisms that drive this speciation. This study aims to show that the differing environmental pressures and behaviors in the coastal and pelagic zones lead to genetic variation in these distinct population groups. This study consisted of a large-scale whole genome resequencing of 4 Tursiops individuals from 3 populations to ~10x coverage located in the western North Atlantic (data obtained from Duke University sampling effort) and 57 Tursiops individuals located in the western North Atlantic, eastern North Atlantic, and eastern North Pacific (data obtained from Louis et. al, 2021) to observe population variance in each region. This study shows distinct population formation in the three regions and provides a comprehensive overview of the genes under possible ecological selection. These results contribute to the larger evolutionary story of the common bottlenose dolphin and the possibility of speciation driven by the selection of particular genes to better adapt and succeed in an ever changing global environment.