The 100,000 ha Sevilleta National Wildlife Refuge (SNWR) in central New Mexico lies in a transition zone that straddles several major biomes of the Southwest: Great Basin Shrub-Steppe, Mogollon Pinon-Juniper Woodland, Great Plains Grassland and Chihuahuan Desert. In the past six years (1989-1994), collaborating with the University of New Mexico s Long Term Ecological Research (LTER) program, 3,235 rodents (28 species, in 4 families) were collected and identified from permanent collecting sites on the three major habitat types (grassland, desert/creosote, woodland) of the SNWR. Hosts were necropsied for endoparasites (protozoa coccidia , helminths) and some ectoparasites. This project will identify a nd analyze all the parasites found in these hosts and in hosts that will continue to be collected during the next three years of this study. By 1998, the project will have put in place the means to easily identify and monitor the parasites form all mammalian hosts caught through the year 2000 on the LTER Phase II grant, and into perpetuity on subsequent renewals. The data to be collected will be unique for several reasons: 1) This will be the first complete inventory of a natural assemblage of parasites form all mammalian (rodent) hosts in three different communities, each form a distinctly defined geographic locality (habitat type) over the period of a decade, and beyond; 2) This study is part of a multidisciplinary approach to address conceptual issues of climate change on ecosystem structure and function at multiple scales (individuals, communities, etc.) and correlative data from these related studies will strengthen and contribute to the robustness of this data set; and 3) As the only parasite study on any of the LTER projects nationwide, it will provide an ideal model, and perhaps incentive, for parallel long-term studies of parasite communities to be examined in a variety of other habitat types, and form a variety of different perspectives, at other LTER sites in the network. Upon completing this work the project team will be able to use these long-term data to try to understand the dynamics of natural host-parasite assemblages. Hypotheses then can be erected to test/address at least questions: How do the different parasite communities colonize, mature, climax and senesce over time (or do they?)? Do they vary in response to abiotic ( climate change) and/or biotic (dispersal, colonization) factors? What temporal/spatial scales, and among what kinds of organisms, do coevolutionary processes influence the community organization of these parasites? Studies of the dynamics of multiple, coexisting species are confined primarily to microtine rodents and have hinted that multiannual cyc les tend to be synchronous (Brown and Heske 1990). Are similar patterns seen for parasites of our desert rodents? Answers to these questions relating to community structure, as well as to questions concerning parasite biodiversity on the SNWR, can be addressed partially or completely by the information gathered on the parasite species infecting rodents collected on the SNWR. Initial emphasis of the work will be on identifying all the parasites collected, by processing to completion what will eventually be 9 consecutive years of parasite data, and on training the undergraduate and graduate students involved in the art of taxonomy and nomenclature of parasitic protozoans and helminths, to begin to supply some of these answers.
