Former Graduate Students

Ellen Martinsen, Ph.D.
NSF Postdoctoral Fellow
National Zoological Park, Washington
e-mail Ellen

Ellen Martinsen has been an avid ornithologist since the age of ten, 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.

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 substantial (52 families in 11 orders), and includes large samples of over 20 species of warblers, many other passerine birds, waterfowl, owls, and hawks. The data are analyzed to compare morphlogical 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 a multi-gene approach.

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. See the "publications" section to read these papers and others to come.

Ellen was honored with the EPA STAR Graduate Fellowship for three years of research on malaria parasites. In August, 2008 Ellen was given the prestigious American Ornithologists Union Nellie Johnson Baroody Award for the outstanding student presentation at the joint bird biology meetings in Portland, OR. She is now a Postdoctoral Fellow at the Smithsonian/National Zoo in Washington an NSF fellowship.

Anne Vardo-Zalik, Ph.D.
Postdoctoral Fellowy
University of California, Irvinet
e-mail Anne

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. Anne chose to move to Penn State where she has just completed a highly successful first year of teaching. Anne's newest project returns to the transmission biology of Plasmodium mexicanum at the California study site.

Susan L. Perkins, PhD
Assistant Curator
Division of Invertebrate Zoology
American Museum of Natural History
Central Park West at 79th Street
New York, NY 10032
e-mail Susan
Susan received her undergraduate degree from the State University of New York, and then devoted a few years to the study of bat ecology and behavior with field work in Trinidad. She subsequently developed an interest in parasites, and came to the lab to pursue the Ph.D., finishing in 2002. Susan studied the diversity of malaria parasites, and published the largest phylogeny of those organisms, including species from all the continents and from a broad range of vertebrate hosts. That paper is now one of the top cited for the Journal of Parasitology. (In the past few years, Susan has been collaborating with graduate student Ellen Martinsen on an even larger phylogeny of the parasites.) During her grad research, Susan also found a cryptic species of lizard malaria parasite, the first such finding using molecular data. Susan tracked the evolutionary history of three species of Plasmodium from Anolis lizards throughout the eastern Caribbean, and took 11 field trips to the islands over a three year period. Susan was awarded an NSF predoctoral fellowship from the University of Vermont training grant, and then a NSF postdoctoral fellowship in bioinformatics. After several years as an Assistant Professor at the University of Colorado, she accepted a position at the American Museum of Natural History where she recently received tenure and is a permanent member of the professional staff at that great institution. Susan's publications include the work on malaria parasites as well as the bacterial symbionts of leeches, and systematics of bats. She now serves as an editor for Journal of Parasitology.

Her publications on malaria parasites are included in the publications section of this site.

Rebecca Eisen, PhD
Division of Vector-Borne Infectious Diseases
Centers for Disease Control and Prevention
PO Box 2087
Fort Collins, CO 80522
e-mail Becky
Becky Eisen received her BS degree from the University of Michigan in 1995, and then joined the lab to complete the Ph.D. in 2000. She developed an interest in parasites while an undergraduate student and during summers at the University of Michigan field station. For her Ph.D. project Becky studied the life history traits of Plasmodium mexicanum, both in experimental infections and in a massive mark-recapture project that lasted four seasons. This was the longest and largest mark-recapture study of any malaria parasite of wildlife. Becky sought training in GPS techniques and put the skills to use in a study of the fine-scale patterns in prevalence of Plasmodium mexicanum in the fence lizards at Hopland. After graduate school, Becky joined the laboratory of Robert Lane as a postdoctoral fellow at UC-Berkeley. There she studied the ecology, transmission biology, and distribution of Lyme Disease in both tick vectors and various wildlife species. She is now at the CDS working with plague ecology. Becky has published dozens of papers in major journals such as Proceedings of the Royal Society, Journal of Parasitology, and Parasitology.

Her publications on malaria parasites are included in the publications section of this site.

Christine Staats, MS, MD
Christine Staats began her undergraduate years at the University of Massachusetts, transferring to complete her degree in Biology at the University of Vermont. As an undergraduate she was a work-study student in the malaria lab, and was a Research Assistant at the Hopland site for a summer. After graduation Chris worked as a technician in a bat physiology laboratory at UC-Berkeley and then in the Medical School here in Vermont. She returned to UVM to pursue the MS in the lab. Chris did her MS research in the Caribbean islands, living on Saba, Netherlands Antilles, for several months to complete a detailed study of the virulence of three species of Plasmodium infecting the endemic Saban anole. She traveled throughout the eastern Caribbean islands to study the biogeography of lizard malaria, and to conduct an among-species test of the Hamilton-Zuk hypothesis. This was a very productive MS project, leading to fully five publications in journals such as Oecologia and Biotropica. After receiving her MS, Chris entered medical school and is now a physician in family practice in Vermont. Chis lives in Burlington with her husband, Brian Perkins a well-known musician, and daughter Ella.

Sarah M. Osgood, MS
Sarah first was an undergraduate work-study student in the malaria lab, and completed her senior research project in collaboration with graduate student Susan Perkins. She worked up a nested PCR method to detect very weak infections of Plasmodium mexicanum in fence lizards, then compared the prevalence of subpatent (under the microscope) infections at sites with high and low overall prevalence. The research suggested a life history strategy of the parasite to remain at low parasitemia at sites with infrequent transmission. The work resulted in a frequently-cited paper in Molecular Ecology. During that busy time, Sarah spent two summers at the Hopland site, as a field assistant for graduate student Becky Eisen. Sarah then worked in a research laboratory in biochemistry where she learned a broad array of techniques, and also met her future husband. She returned to the malaria lab to pursue the MS degree. Her graduate project examined the influence of clonal diversity on the sex ratio of Plasmodium mexicanum, working both at the Hopland site and the UVM laboratory. Her thesis resulted in three publications in the journals Parasitology and Journal of Parasitology. She is now performs the amazing task of balancing a position in a research lab with being the mother of two small children.

Roberto Fialho, MS, PhD
Roberto Fialho received his undergraduate education at the State University of Rio de Janeiro, perhaps the finest university in Brazil. His undergraduate research thesis centered on the feeding biology of a small frog. He found that the frog eats only the fruit of the dominant shrug in the habitat (a fruit-eating frog!), but spends the nights in the water pool within a large terrestrial bromeliad. The frog defecates the fruits seeds in the only place in the environment where the seeds will find enough moisture to germinate. The shrub grows and eventually kills the bromeliad. Thus, the entire structure of the habitat depends on the frog behavior. This work resulted in two publications. Rob then came to the malaria lab. His MS project examined the influence of temperature on the rate of development of Plasmodium mexicanum in its insect vector (a sandfly). He found that the parasite manipulates the insect to choose a warmer location, thus allowing the parasite to complete development before the sandfly takes its next blood meal. This work was done at the Hopland site, and resulted in a publication in the Journal of Animal Ecology which received considerable attention. Roberto then pursued the Ph.D. in ecological genetics with Dr. Lori Stevens in our department. He looked at the influence of Wolbachia symbionts on the biology of beetle hosts. Rob bravely fought cancer throughout his graduate career, and his Ph.D. work was published after his death in 2000 in several journals including the Proceedings of the Royal Society of London. Rob received his Ph.D.posthumously in 2002. Rob gave the lab his three-part motto, that rules whenever things get tough: "Never give up, never give up, never give up." Dr. Michael Upton MD has established a fund to honor Rob by awarding a grant each year to an outstanding graduate student.

Denise Dearing, MS, PhD
Associate Professor
Department of Biology
University of Utah
Salt Lake City, Utah 84112
e-mail Denise
Denise received her MS from the University of Vermont, then went on for the PhD at the University of Utah. While in the UVM laboratory, she pursued two very different projects. First, she examined the impact of infection with Plasmodium mexicanum on male-male competition for mates of the fence lizard host. This was published in Oecologia before Denise even began her "real" graduate project. She then spent over a year on the Caribbean island of Bonaire, examining the diet choice of the herbivorous lizard, Cnemidophorus murinus. The project resulted in four publications, including a major work in Ecology. Her PhD studies on diet selection in the Pika are a classic, and led to her receiving highest honors from the Ecological Society of America and several prestigious postdoctoral fellowships. After extensive field work in Australia and Tasmania, Denise had to return to the real world and accepted a position back at the University of Utah. She now divides her time between projects on diet of herbivores and (finally returning to the really interesting problems!) the parasite-host ecology of Hanta virus and rodent hosts. Her recent publications have been in major journals such as Chemical Ecology and Emerging Infectious Diseases To learn more about the Dearing lab projects, visit her web site, address above.

Diane Faile, MS
Throughout her life, Diane Faile has had very broad interests, including literature, writing, gardening, and nature. As an example of that eclectic style, Diane received degrees in Biology and English from Bowdoin College, a distinguished liberal arts college in Maine. She came to the malaria lab, but revealing a strong independent streak, chose a research project in animal behavior, and organized a team of volunteers to assist in a massive study of nesting behavior of the pelagic cormorant, a seabird that nests on cliff faces on the Pacific coast of California. The study, the largest ever done on that species, is now referenced in standard reviews in ornithology. Diane then went on to receive a degree in environmental law from the University of Oregon, and worked for some years in that field. In recent years she has returned to her interest in literature, becoming an partner in an e-publishing firm, Mind Like Water, often serving as an editor and mentor for writers.

Steve Ressel, MS, PhD
College of the Atlantic
105 Eden Street
Bar Harbor, Maine 04609
After receiving his undergraduate education in Biology from Millersville University in Pennsylvania, Steve was a research technician for several years at the Penn State Medical School, then came to the malaria lab for his MS program. Steve has broad interests in life science, and so conducted field work on the diet selection of a herbivorous lizard on Aruba island (resulting in a publication in Copeia), then additional field work to identify lizard malaria parasites in the lizards of Costa Rica. Steve was interested in how parasites influence the sexual selection for their hosts, and was honored to discuss these issues with W. D. Hamilton when Bill visited our department. This meeting occurred just before the Hamilton-Zuk hypothesis was published in Science, and led Steve to test the hypothesis with a study of the sexually dimorphic color of fence lizards at Hopland infected with Plasmodium mexicanum. This early work on the H-Z hypothesis resulted in a paper in Oecologia. Steve then went on for the PhD degree at the University of Connecticut, again switching gears to study the biophysics of frog calling, with much field work in Central America. He is now a Professor at the College of the Atlantic on the coast of Maine where his office looks out over the Atlantic Ocean! Note his mailing address is on Eden Street.

Carl Bromwich, MS, MD
Kuujjuag, Canada
Carl Bromwich studied as an undergraduate at Franklin and Marshall College, was the first graduate student in the malaria lab. His MS project was a two year mark-recapture study at the Hopland site, the most detailed look at the dynamics of natural infection of any malaria parasite of nonhumans. These results were published in Ecology. He then spent six months in Sierra Leone in west Africa to study the virulence and prevalence of two species of Plasmodium in Agama lizards. Several more publications emerged from this study. Carl then received his MD degree from the Dartmouth Medical School and for some years has been a physician in the Canadian Arctic, 1000 miles north of Montreal. Because local cuisine often includes aged meat from marine mammals, botulism is a hazard. Carl has successfully treated more people suffering from botulism poisoning than any other physician.