Determining Species-Specific Seed Shadows Using Molecular Genetic Methods

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Intellectual Merit: Measuring and analyzing seed dissemination into the environment is considered a major limitation in seed dispersal and plant recruitment studies. To date, seed shadows have been based on data collected from radio-tracked animals or from seed traps. In the former method, seed shadows are probalistic as dissemination is based on average gut passage times and distance moved during some time period, but data do not provide a means to evaluate species-specific differences in animal-generated seed shadows. In the latter case, seed rain provides a direct measure of seed arrival into microenvironments, although the contribution of different animal dispersers is not possible to discern. Dissecting out individual ecological roles of animal dispersers is necessary to understand the evolutionary impacts of seed dispersers on plant demography. This SGER proposal investigates a new method for directly measuring species-specific seed dissemination by birds using molecular markers and fecal samples. Fresh bird droppings that contain seeds are readily found in forest environments or collected in seed traps. In this exploratory research project we will collect fecal samples containing seeds from known species of birds (i.e., captured birds) and conduct genetic analyses on the bird dropping to get a "species signal". This preliminary work is necessary to test the ability of detecting microsatellite markers from bird droppings. Without sufficient evidence that this novel technique will function, any proposal relyingon this method to examine interspecific differences in seed dispersal function by birds is unlikely to be successful. If successful, this technique could revolutionize our studies on seed-dispersal efficiency in tropical lowland forests as it would provide a means to directly study seed dissemination into microenvironments that differ in seed and seedling establishment conditions. The application of this novel technique would allow us, for the first time, to develop the critical link between seed disperser behavior and plant demography, and thus, provide the key empirical data to determine the influence of animals on plant demography.Broader Impact: The proposed research effectively combines the ecological,behavioral, and molecular genetic expertise of the principal investigators and provides an avenue for new collaborative research that will enhance research programs of each senior investigator. If we can successfully develop the methods to obtain species signals using molecular genetic data from bird fecal samples, this method will likely become adopted by many researchers and applied to a wide range of ecological, population, and behavioral studies. Field and laboratory components of the research program will also provide key opportunities for a student from UM-St. Louis and from Latin America to gain research experience.