Former Graduate Students

For her Ph.D. project, and now her full menu of studies she has worked with the invasive Asian "jumping worms" that are causing serious problems in forests and gardens across the United States. Several species of these earthworms can reach very high densities in forest soils and essentially eliminate the natural understory. The jumping worms are very difficulty to identify, and impossible as eggs, hatchlings, and juveniles. Maryam has studied the ecology, distribution, and genetics of the earthworms, and now has developed a rapid molecular method for identifying them to species (even as eggs!), and has used the population genetics of the worms to understand their origin (Japan), genetic variation among sites, and reproductive biology. The goal of these studies is to control the spread of the jumping worms, so Maryam has developed methods to keep them in the laboratory, even through their life cycle, and is testing various biological control methods, such as fungi. These studies have been appearing in a variety of top journals (some are listed in the publications section of the web site).

The threat of the earthworms, as well as their various common names of "jumping worms", "snake worms" (both because of their very active behavior, and "spitting worms" (you don't want to know!), and their often very high densities in compost piles and even gardens, have led to lots of interest by the press. Thus, Maryam has been featured in a variety of sites, and even appeared in a nice color photograph in a story in the New York Times (see it here: PDF)

Maryam worked in the parasitology lab because we study the parasites of the earthworms, so the connection made sense to help us understand the biology of the worms and how that information would connect to the transmission biology etc. Maryam began her molecular studies in the parasite lab, then established a full molecular lab in the Plant and Soil Science department.

When not working on her many projects, Maryam is an avid hiker, and is completely devoted to her pet parrot. She is also active in several graduate student groups on campus.

Allison entered our graduate program in the fall of 2009 and received her Ph.D. in August 2014. While a graduate student, Allison received three wonderful honors: She was awarded the EAPSI NSF summer fellowship to study with Robert Poulin in New Zealand. Her work with Dr. Poulin centered on how the larvae of a marine trematode worm finds its preferred substrate, and resulted in a publication in Journal of Parasitology. That study required Allison to spend time splashing in the winter seawater of New Zealand's beautiful coast. Soon after learning of the EAPSI award, Allison learned that she was awarded the National Science Foundation Graduate Fellowship for three years, which is perhaps the highest honor for a science graduate student. Then, to complete the NSF trifecta, Allison was awarded the NSF Doctoral Dissertation Improvement Grant to student the ecology of the vector of the lizard malaria parasite Plasmodium mexicanum .

Anne Vardo-Zalik received her undergraduate degree and MS in Marine Biology from the University of Massachusetts. Early in her education she developed a life-long interest in marine sciences, which led her to the University of Massachusetts programs. For her MS project Anne studied the tapeworms of sharks, and discovered three new species. She then placed her findings into a broad biogeographic picture of shark distribution in the North Atlantic.

In 2002 she joined the malaria lab to pursue the Ph.D. Anne first characterized a number of variable micro-satellite markers from the lizard malaria parasite, Plasmodium mexicanum. Using these markers she determined the clonal diversity of the parasite both within and among infections. Anne then determined the role of clonal diversity on the life history, virulence, and transmission biology ofthe parasite. Her studies were conducted both at the Hopland site in California (the photograph shows Anne at her site) and the Vermont laboratory.

Anne has published her work in papers in Journal of Parasitology, Molecular Ecology Notes, and Molecular Ecology, International Journal for Parasitology, Parasitological Research, and Ecology. These papers are listed in the "publications" section of this site. Anne found that there is substantial genetic diversity within the P. mexicanum cycling in the lizards at Hopland, even at sites where the parasite has very low prevalence. Because multiclone infections are common at the site, Anne next asked if genetically complex infections display different life history traits and costs to the lizard host. The answers were surprising. She found that single-clone infections all followed a narrow range of rates of increase over time and final parasite density, but mixed-clone infections were much more variable. That is, infections with high parasitemia were the mixed-clone infections, but not all mixed-clone infections followed this virulent pattern. Anne measured the effect of infection on the hosts and found that infection has costs based on a variety of physiological measures, but the most complex infections, with greater than 3 clones, were not virulent and for some measures, these lizards appeared more healthy than lizards not infected with the parasite! Anne then looked at the transmission efficiency of the parasite and found that all clones most often were transmitted to the vector, and relative abundance in the lizard matched relative abundance of clones in the vector. In Anne's final summer as a graduate student, she presented talks at major meetings, the American Society of Parasitologists meetings in Mexico and the Protozoology meetings. She received the outstanding student talk award at both meetings (two for two!).

Anne is a dedicated teacher, and mentored a number of undergraduates over her career in our department. These students really shined under Anne's guidance, and are off to fine careers of their own. Anne completed her Ph.D. program at the University in May, 2008 and began a postdoctoral program at the University of California, Irvine with Dr. Guiyun Yan, one of the world's most distinguished malaria researchers. She has traveled to Kenya doing the fieldwork for a study on the genetic diversity and transmission biology of Plasmodium falciparum. In January, 2009 she was funded by the NIH for another three years of postdoctoral studies on human malaria parasites, but was then offered a position as Assistant Professor of Biology at Penn State University, which she could not turn down. She is now Assistant Professor of Biology there, and has been honored with the outstanding teacher of the year award at that university that prizes teaching so highly. Anne teaches a variety of courses at Penn State, including parasitology (of course!) and has involved students in her ongoing research on malaria parasites. Anne continues to be a collaborator with Dr. Allison Neal of Norwich University.

Ellen Martinsen has been an avid ornithologist since the age of eight, when she began working with a local wildlife rehabilitation center. Ellen received her BS in Biology from the University of Vermont in 2000. After a few years working as an environmental educator, she returned to the university to pursue the Ph.D. and competed the degree in spring, 2009. While a graduate student she was named the outstanding Teaching Fellow of the year and was honored with the EPA STAR Graduate Fellowship for three years of research on malaria parasites. In August, 2008 Ellen was presented with the prestigious American Ornithologists Union Nellie Johnson Baroody Award for the outstanding student presentation at the joint bird biology meetings in Portland, OR. She then received both a prestigious National Science Foundation Postdoctoral Fellowship and a Smithsonian Postdoctoral Fellowship to work with the avian malaria team at the National Zoo. While there she received a Morris Foundation research grant. She is now a collaborator on a large NSF-funded project on the birds of SE Asia, being the parasite expert on the project. Ellen divides her time between UVM where she is an Adjunct Professor and the National Zoo, and has rejoined the malaria laboratory here to do research and mentor students.

Ellen studies the biodiversity of avian malaria parasites of throughout the USA and several international sites (the photo shows her in the Dominican Republic with a friend). She combines study of morphological traits with modern molecular techniques and phylogenetic analysis. Ellen has sampled >4200 birds of over 230 species, and has sequenced hundreds of infections of Plasmodium, Parahemoproteus, Haemoproteus, and Leucocytozoon. The diversity of birds included in Ellen's study is thus very large. The data are analyzed to compare morphological vs. molecular definitions of taxa, to understand host range and possible host switching, and to define the true diversity of the parasites. Ellen also studies the overall evolutionary history of the malaria parasites, using multi-gene approaches.

Ellen's publication in Molecular Phylogenetics and Evolution, presents a large phylogeny based on four genes from the parasites' three genomes. The result finds that major clades are associated with vector shifts into different dipteran families. Two other publications have appeared in Parasitology. The first (in collaboration with Ilan Paperna of Hebrew University) focuses on species concepts as applied to malaria parasites. Species identified by morphology are compared using genetic distance and phylogenetic analysis. The second asks if the current subgenera of malaria parasites are monophyletic groups. Another publication, in Journal of Wildlife Diseases presents a survey of the avian malaria parasites in California birds.

Ellen's most recent paper showed that Plasmodium, long thought to be absent from any mammal hosts in the Americas, and absent from any deer world-wide, is present in our White-Tailed Deer (WTD). She found two diverse lineages, probably two species, that infect WTD all over the eastern USA. The parasite is common in WTD, with prevalence reaching a quarter of the deer infected at some sites. Ellen was able to date the divergence of the two lineages to about the time the WTD evolved from its ancestor that had traveled to the Americas via the northern landbridge. This paper, in Science Advances caused something of a sensation, appearing in hundreds of news and science websites around the world. A short video on the study appeared on the popular science website IFL Science, and was viewed 1.5 million times over the next 24 hours!

Ellen's current research is on the malaria parasites of endangered birds and the diversity of parasites in the birds of Borneo.