Metapopulation models are important tools for understanding distribution and abundance of organisms at large spatial scales. Because these models attempt to integrate local population dynamics with immigration and extinction events occurring between sites, they form a bridge between the traditionally separate domains of population ecology (local abundance) and biogeography (regional occurrence). Freshwater mussel communities in rivers provide an exemplary system in which to assess metapopulation models across different regional scales: within a stream itself (small drainages) and within a network of streams (major river drainage). Mussel communities are naturally distributed in patches because they only occur on appropriate substrate within a river. Local populations are prone to frequent extinction because of the shifting course of rivers which redeposits sediment and eradicates mussel beds. Dr. Vaughn will take advantage of historical (near-fossil) data on mussel assemblages in the Red River drainage along with SCUBA- facilitated inventory of current mussel communities in order to quantify colonization and extinction rates through time and over spatial scales from local to regional. %%% Rudimentary metapopulation models have been evaluated with datasets that emphasize current assemblages of species. Data on temporal fluxes are needed to begin to quantify rates and patterns of colonization and extinction over regional spatial scales. Dr. Vaughn in a research planning grant is beginning to assemble such datasets by concentrating on mussel communities in the Red River drainage. The work takes on added urgency in light of the recent introduction of an alien asian clam that may prove an aggressive competitor in the region.
