RESISTANCE OF MARINE PALECOMMUNITIES TO PRIMARY PRODUCTIVITY DISRUPTION IN THE LATE MIOCENE OF THE DOMINICAN REPUBLIC

The Neogene uplift of the Central American Isthmus was coincident with a significant regional marine extinction in the Caribbean. Changes in paleocommunity structure can provide information about ecological changes leading up to the separation of the Caribbean and Pacific Oceans. Our study focuses on stratigraphically adjacent marine mollusc communities from the Late Miocene Dominican Republic. All shells complete enough to be identified to family were counted in each sample. Relative family abundance and trophic properties were used to characterize each sample, allowing the construction of metanetworks representing trophic relationships. Preliminary results show a significant change between samples in the abundances of taxa assigned to two bivalve families.

To build the networks, families within the community are parameterized ecologically and partitioned into guilds, where members of a guild share similar ecological characteristics such as position on substrate, motility and mode of feeding. Links between guilds represent potential trophic interactions of guild members. The trophic networks were reconstructed probabilistically to reflect uncertainty in both community composition and biotic interactions. We used a trophic network model to simulate disruptions of primary productivity to each community and assess the sensitivity of the networks to disturbance. Because the extent to which extinctions propagate through networks is a function of both taxonomic and ecological diversity, as well as the magnitude of the disturbance, we predict that the communities represented by the samples will respond differently to perturbations of the same magnitude.