RESEARCH​
TAMPA BAY TREMATODES
Every semester students in my parasitology class necropsy fish and some students choose to make molecular identifications of the parasites they find. Through their research, I have learned that: 1. marine parasites are highly understudied and 2. efforts to catalogue marine parasites in Florida waters hasn't happened in over 50 years. Kathleen Gillis drove the lab's research into a striking yellow trematode recovered from fish fins. Liza Walker will take the lead on continuing research on this worm in Fall 2025. Dr. Carlos Santamaria and L. John Ambrosio, MSc. have been helping us learn more about the identity and biology of this worm. It would be great to expand this project to update Florida's marine parasite catalogue and shed more light on these less explored critters.
Climate-driven host species introduction and its effect on symbiotic associations in Tampa Bay, Fl
L. John Ambrosio, MSc., Markayla Harrison, Aidan Soldan, Gwenen Hupp, and I are investigating the symbiotic relationship between a species of pea crab (Tunicotheres moseri) and sea squirts in Tampa Bay. Specifically, this project explores how climate-driven range expansion of tropical species into temperate Florida ecosystems may impact their relationships. The pea crab lives inside the body cavities of solitary ascidians throughout the Caribbean Sea, western Atlantic and Gulf of Mexico. Within Tampa Bay, T. moseri inhabits two host species common to temperate marine ecosystems: Styela plicata and Molgula occidentalis. A recent climate-driven range expansion of the tropical ascidian Phallusia nigra into Tampa Bay has added a new host for local T. moseri and has the potential to alter the preexisting symbiotic relationship between T. moseri pea crabs and their local hosts. This project addresses two major questions about this climate-driven introduction of a novel host species in Tampa Bay: (1) What is the prevalence of P. nigra ascidians relative to historically common S. plicata and M. occidentalis ascidians in Tampa Bay? And, (2) How has the range expansion of P. nigra into Tampa Bay altered the host-use of local populations of T. moseri pea crabs? We are addressing these questions by performing field surveys to measure host species densities in the bay, measuring the presence of the pea crab in each host species, and by measuring pea crab and ascidian host traits.
PARASTITE BEHAVIOR
As a postdoctoral researcher at the University of Florida, I investigated consistent individual differences in behavior within and among mite populations. Working with collaborators, we have revealed significant repeatability in individuals’ attachment behavior, where some individuals consistently attach to hosts when repeatedly exposed while others never attach to a host. We are now assessing the costs and benefits associated with each of these behavioral phenotypes and asking how these consistent individual differences in behavior can influence general processes in parasite ecology like host selection and parasite aggregation. Most recently, Anngelyk La Luz and I were working to investigate potential differences in the microbiomes between mites that repeatedly attach and do not attach. It's possible that endosymbiotic bacteria and/or symbiotic gut bacteria contribute to the individual behavioral differences in these mites. We are currently working on a manuscript.
EVOLUTION OF PARASITISM
Although parasitism is a ubiquitous lifestyle, little empirical evidence exists for how and why parasitism evolves from free-living lineages. A commonly proposed hypothesis for the evolution of parasitism posits that transient host-associations served as evolutionary stepping-stones towards more obligate parasitism. For this hypothesis to hold, host-association behavior must be heritable. Using artificial selection I experimentally evolved a facultatively parasitic mite (Macrocheles muscaedomesticae) to exhibit increased propensity to attach to a fly host (Drosophila hydei). This branch of research provides some of the first evidence for heritability in parasite host-association behavior, and empirical support for a major assumption regarding how parasitic lifestyles evolve
DO MITES SERVE AS IMPORTANT DISEASE VECTORS AMONG ARTHROPODS?
Emily Stone and Elise Richardson, an undergraduate and Master's student in the Keiser lab (https://www.keiserlab.com/people) at the time, performed experiments that demonstrate mites are capable of vectoring the beautiful (red pigmented growth in image) but deadly arthropod pathogen Serratia. The image to the right shows the post-mortem cultures of a mite that had previously attached to a fly that was experimentally infected with Serratia (top) and an uninfected control fly that the mite at the top attached to after attaching to the infected fly. With help from Dr. Brian Lazzaro (http://www.lazzaro.entomology.cornell.edu/index.html), we hope to soon get back into the lab to determine whether mites are truly ingesting bacteria and transmitting it to other flies when feeding on their hemolymph or if it is sloppy contact-transmission. It could be that mites' legs and/or mouthparts become contaminated after feeding on an infected host and spread it to other hosts they subsequently contact.
