Mathematical Biology Seminar Jennifer Koop University of Utah 3:05PM, Wednesday, September 15, 2010 LCB 225 The demise of Darwin's finches? Abstract: The Galapagos Islands currently stand as one of the most well preserved island ecosystems, with no known extinctions of avian or mammalian species. However, a recently introduced parasitic fly, P. downsi, threatens to change that standing. The larvae of P. downsi are parasitic and blood feed on nestlings, reducing both growth and survival. P. downsi has now been documented on 11 of 13 major islands within the Galapagos and has been found in the nests of nearly every land bird, including all species of Darwin's finches. I will discuss a study we've performed using an experimental manipulation of parasite abundance to assess fitness costs in a single species of Darwin's finch, the medium ground finch. We have found noticeable variation in fitness costs and parasite abundance over the course of this three-year study. I will conclude by discussing how we have used these dynamic fluctuations to create a simple model that examines both host and parasite population persistence.