Ecologists are well-equipped with theory for competition between species that consume and deplete shared resources. Resource depletion, i.e., consuming resources quickly enough to limit the resources available to other consumers, is a well-established pathway by which different consumer species interact. Unfortunately, approaches based on resource depletion apply to only a subset, and perhaps a minority, of consumer-resource interactions in nature. Many consumer species consume resource organisms only partially, and do not appear substantially to reduce available resources. This includes many herbivores, which leave much green plant material unconsumed; non-fatal parasites, parasitoids, and pathogens, whose hosts can continue to forage, mate, and otherwise go about life while infected; and mutualists such as pollinators, defenders, and cleaners, which collect rewards provided by hosts in return for these services. A key feature of such species interactions is that resource organisms respond to partial consumption via changes in their survival, growth, and reproduction. The effects of these demographic responses on resource competition have been little studied. Building on previous promising theoretical results showing that resource demographic responses can critically affect the outcome of competition, this project will develop mathematical theory to accomplish three goals. First, general theory will establish the different possible roles of the demography of partial consumption in biological settings, ranging from competition between herbivores to competition for access to mutualistic partners. Second, models will integrate plant demographic responses to herbivore attack with other known pathways of interaction between the different herbivores of a shared plant host. Third, applications such as biological control of resource populations will be investigated quantitatively.
The theory developed in this project will have broad application within and potentially beyond the ecological sciences. Further, the project will support the quantitative training and mentoring of a postdoctoral researcher in the construction and analysis of mathematical models to address ecological questions, as well as training in presenting results to non-mathematical audiences. Attempts will be made to recruit applicants from groups underrepresented in STEM fields. Postdoctoral involvement will also broaden dissemination of research results through increased publication and presentation.
