This dissertation enhancement grant supports a US graduate student, Ms. Caroline Christian, working under the guidance of Professor Maureen L. Stanton, of the Center for Population Biology at the University of California, Davis. Ms. Christian will conduct a demographic analysis of the life history variation and seed dispersal in the ant-dispersed Proteaceae of South Africa.
Many animals serve as mediators for seed dispersal, but due to habitat alterations many seed dispersers are being lost, resulting in a decline in many plant species. Ant seed dispersal is the major seed dispersal method in many fire-prone shrublands worldwide. This dispersal method is especially important in the Cape Floristic region of South Africa, which contains an unusually high number of rare ant-dispersed species. Through its displacement of native ant dispersers, the non-indigenous Argentine ant is reshaping ant seed-dispersal mutualisms in this region, but little is known about the long-term consequences on plant populations. Ms. Christian will examine the two potential selective forces that have shaped the two life histories found in the ant-dispersed Proteaceae: seed dispersal by ants, and fire frequency. She will examine the population dynamics of two Proteaceae species which share similar life histories, but have different reproductive characteristics. Through controlled field experiments, Ms. Christian will examine how the components of seed dispersal influence seed dormancy, seed survivorship, and seedling establishment. Data from the field experiments and from demographic plots will be used to develop a matrix simulation model to predict which types of species are most sensitive to alterations in seed dispersal methods. This predictive model can have significant conservation applications. Dr. Hamish Robertson, a leading African ant taxonomist at the South African Museum, will provide guidance on this project to Ms. Christian.
The results will provide important new knowledge about plant population dynamics. This project will also support an international research experience very early in the career of an outstanding graduate student.
