FOSSILS, COEVOLUTION AND CONSERVATION: USING THE PAST TO EVALUATE THE INFLUENCE OF HUMAN ACTIVITIES ON THE EVOLUTION OF A PREDATOR-PREY INTERACTION

A common problem in conservation studies is determining the baseline conditions that existed prior to human influence. Although it is increasingly acknowledged that humans have had a deleterious effect on ecosystems, the absence of pristine environments makes it difficult to impossible for scientists to disentangle natural changes in ecosystems from those induced or magnified by human activities.

The nature of the predator-prey interaction between venerid bivalves and busyconine whelks presents a unique opportunity to investigate whether human activities have altered the natural coevolutionary process. This interaction leaves a characteristic trace fossil record of repair scars left on the shells of both predator and prey (Dietl 2003). A comparison of the frequency of these scars permits a conservative estimate of the strength of selection before and after human influences on the environment.

Preliminary results suggest that anthropogenic effects have not severely altered the selection regime (indexed by the frequency of repair scars) in which this coevolving species interaction is embedded. Natural variation in the frequencies of unsuccessful whelk predation on the shell of Mercenaria and feeding-induced damage on the whelk's shell of modern samples are not statistically distinguishable from Pleistocene samples. The inclusion of data from additional fossil and modern samples will allow more detailed evaluations of changes (including comparisons of body size and growth rate) that might have occurred since human influences on the environment began. This kind of information is crucial if we are to conserve the coevolutionary process that helps shape the diversity of life for future generations.