The Effects of Migration, Productivity, and Scale on Metacommunity Dynamics

Florida State University, Tallahassee FL

Investigators

Abstract

0091776. Thomas Miller. Understanding patterns of community organization requires a focus on multiple scales of time and space. A metacommunity perspective in its most simple form distinguishes mechanisms that operate locally, such as competition and predation, from those which operate at broader spatial and temporal scales, such as migration and extinction. Although the conceptual basis and ramifications of such scale-dependence are well developed, few empirical or experimental tests have been undertaken to address aspects of metacommunity theory. The proposed research uses "inquiline" (tenant or dweller) species, which live in water-filled leaves of pitcher plants to quantify the effects of the rate and spatial scale of dispersal on the local and regional structure of communities. Inquiline communities contain mosquito and chironomid larvae, as well as copepods, cladocerans, aquatic mites, rotifers, protozoa, and bacteria. The primary source of energy to this aquatic system comes from dead invertebrates that are captured by the host plant rather than from photosynthetic production. These communities are convenient natural microcosms because of the ease with which they can be manipulated and replicated in field conditions. They are especially appropriate for studying metacommunity dynamics because interactions clearly can be distinguished between those of local (e.g., predation, competition, resource availability) and regional (e.g., migration and disturbance). More specifically, the rate and scale (local versus regional) of migration of species among individual pitcher plant communities, as well as the productivity of the system as a whole will be manipulated to conform to a factorial design, thereby facilitating statistical analyses. Weekly monitoring of the entire community will permit the estimation of the abundance and growth rate of constituent species, as well as the composition and diversity of communities. In tandem, these experiments and observations will allow a deep understanding of the extent to which local and regional mechanisms affect community characteristics, and the degree to which such results are predicated on the production of the system.