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Goodwin - You Can Teach Old Clams New Tricks: Reconstructing Patterns and Timing of Growth - Methods and Applications

You Can Teach Old Clams New Tricks: Reconstructing Patterns and Timing of Growth â Methods and Applications
David H. Goodwin
Department of Geology and Geography, Denison University, Granville, OH 43023, USA, goodwind@denison.edu
Bivalve mollusks are biological chart recorders: their shells contain a record of the environmental conditions experienced during growth. Data is preserved in several forms, principally by periodic growth increments and geochemical variations. Combined analysis of these patterns is a powerful tool for understanding how bivalves grow, how growth reflects environmental variation, and for reconstructing evolutionary relationships among taxa. Cross-calibration of these archives from modern specimens with observed environmental conditions reveals tight correlations with numerous physical and biological signals. Sclerochronologic archives are, however, incomplete due to the onset of senescence. Growth cessations and changing growth rates can reduce the range and resolution of the recorded environmental conditions. Nevertheless, careful analysis reveals that numerous biological and environmental signals are accurately preserved. Furthermore, shell-based environmental records are easily modeled, providing baselines against which observed profiles could be compared. Modeled profiles also elucidate which components of shell-based archives reflect actual environmental conditions versus biologically mediated growth patterns specific to the individual in question. With a detailed understanding of an organismâs growth patterns, one can address a variety of significant neontologic and paleontologic questions. Examples include, investigation of both natural and anthropogenic biogeographic shifts, documenting climate change in the past, predicting the biological responses to global warming, and reconstructing evolutionary relationships.


next up previous
Next: Hadfield & Koehl - Up: Special Symposium - From Previous: Collin - Molecular Insights
Peter Roopnarine 2005-04-12