A persistent challenge in ecology is to understand the maintenance of biodiversity. Ecological theory provides a variety of hypotheses about how competing species can stably coexist, all based on “niche differences” between species. However actually showing that these mechanisms are at play, and strong enough to stabilize the coexistence of competitors, and further strong enough to shape the relative abundance of species in communities, is a challenge. Another hypothesis is that species coexist primarily due to their similarities – i.e. because they both happened to disperse to an environment in which they have similar fitness. In this case immigration and demographic stochasticity are the primary shapers of local communities. The simplicity of this hypothesis has enabled it to be quantitatively formalized into a “neutral theory” of biodiversity maintenance. This neutral theory has the potential to play an important role in ecology, as a quantitative process-based null model whose rejection indicates the presence of processes of interest. However, tests of neutral theory have not yet lived up to this potential. When the neutral model fits data, it seems a stochastic niche model might do just as well. When the neutral model fails, it may be only because it simplifies demographic details unrelated to niches. How can we construct more informative tests of neutral theory, which use its potential as a quantitative process-based null model? In this talk, I’ll describe work going on in my lab towards this aim. Key areas of effort include studying stochastic niche models to better understand what niches do to community structure, studying more complex neutral models to understand what aspects of demographic complexity matter for what types of predictions, and approaching tests of neutral theory in new ways by making use of data for the large-scale relative abundance of species, and for species’ traits.
Coffee and cookies will be served at 4 p.m.