Recent projections of anthropogenically-influenced climate change have emphasized the importance of understanding how organisms and biotic communities respond to perturbations on both the long and short term. Data from the fossil record can be instrumental in such studies, offering the potential to study the response of ecosystems to protracted climate change impossible to observe on human time scales of only a few years. PIs plan to evaluate the influence of climate on the ecology and evolution of marine mollusk faunas from the U.S. Gulf Coastal Plain during the Paleogene (~65-25 million years ago). Their approach allows them to integrate records of mean annual temperature and seasonality with shifts in diversity, community composition and structure, morphology (shape), and evolution. They are particularly interested in learning whether there is a correlation between the magnitude and direction of climate change and the amount and nature of evolutionary or ecological change, including whether or not there are thresholds of tolerance below which an ecosystem and its component taxa do not respond. PIs will generate the paleoclimate record from the chemistry of fossil mollusks and fish otoliths (ear stones), and paleoecological patterns will arise from a combination of existing museum collections, published literature, and new field sampling of mollusk faunas. Lastly, they will reconstruct evolutionary relationships and trends within two dominant mollusk groups - venericard bivalves and turritelline gastropods - that are characteristic of this region and time, and overlay this information on the temperature and ecologic records for a comprehensive picture of faunal response to climate change. Their research will contribute substantially to knowledge of how biodiversity in sub-tropical settings responds to climate change of varying types and magnitudes.
