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RESEARCH INTERESTS
Evolutionary Ecology of Host-Parasite Interactions
Research
For my Ph.D. I studied determinants of host specificity in an unusually tractable host-parasite system: pigeons/doves and their lice (Phthiraptera: Ischnocera). I measured the ability of parasites to establish viable populations on novel hosts by artificially dispersing feather-lice to a series of host species. I found that lice were able to establish on novel hosts if the novel host was similar in size to the native host. Conversely, lice did not establish on novel hosts that differed in size (by >25% in body mass) from the native host. To understand the observed pattern, I also investigated several potential barriers to parasite establishment. I found that preening, a bird's primary defense against ectoparasites, is one barrier. When preening was experimentally impaired, lice established on novel hosts an order of magnitude smaller than the native host. Proximal experiments corroborated these results by showing that lice placed on small hosts were more susceptible to preening because they were physically unable to hide in the feather structures of smaller hosts. These results are consistent with macro-evolutionary patterns in this system; host-switching has occurred most frequently between similar sized hosts. This is interesting because parasite size correlates with host size in a diverse array of host-parasite systems, yet the adaptive basis of this correlation is poorly understood.
For my postdoc, I have been the lead parasitologist on an NSF funded Biotic Surveys & Inventories project in southern China. I have processed over 2,000 individuals of more than 300 species of birds, mammals, frogs, and snakes. From these vertebrates I have collected parasitic fleas, flies, lice, ticks, mites, pseudoscorpians, leeches, acanthocephalans, nematodes, cestodes, trematodes, coccidia and hematozoans. To deal with this large and diverse collection of Chinese parasites, I have developed a network of collaborators from 15 different institutions who specialize on different parasite taxa. I have co-authored taxonomic work on several of these groups (lice, flies, and ticks), and work on several other groups (acanthocephalans, nematodes, and hematozoans) is in preparation. In addition to collecting parasites, I have also sampled Chinese birds for highly pathogenic avian influenza, including H5N1. These samples are being screened in collaboration with staff at the National Wildlife Health Center in Madison, WI. Most recently, my colleagues and I submitted a manuscript detailing the occurrence of avian flu in Chinese songbirds. Our results indicate that songbirds have the potential to spread H5N1 to North America, but current surveillance measures are overlooking this group of potentially infective birds.
Future Directions
I intend to use a comparative approach to investigate ecological factors that may influence the structure of parasite communities. Understanding how ecological factors influence parasite distributions is increasingly important as deforestation, habitat fragmentation, and global climate change are drastically changing natural landscapes. As the environment changes, parasites may spread into new geographic regions, host populations may become increasingly susceptible to certain parasites, and other parasites may face co-extinction with their hosts. The parasites I have collected from terrestrial vertebrates of China offer many opportunities to investigate ecological determinants of parasite community structure. For example, the Chinese parasites came from many sites with habitats that varied in quality from relatively pristine to heavily deforested. This provides a unique opportunity to test hypotheses about the impact of forest quality on parasite communities. The diverse array of parasites that were collected also makes it possible to compare the impact of ecological factors on different types of parasites (endo vs. ecto-parasites, direct vs. indirect life cycles, etc.). In addition to conducting comparisons among different host populations in China, I will soon be able to add comparisons among vertebrate populations in the Philippines. I am one of four Co-PIs on a newly funded NSF Biotic Surveys & Inventories project to survey the terrestrial vertebrates and parasites of the Philippines over the next 5 years.
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