INTRODUCING A “COMMUNITY MODULE” APPROACH TO TEST THE STABILITY OF ECOLOGICAL INTERACTIONS IN THE MIDDLE DEVONIAN HAMILTON FAUNA

The Middle Devonian Hamilton Fauna of the Appalachian basin is a reference example of coordinated stasis. Although the taxonomic composition and richness of the Hamilton fauna is stable over a long time (~4.5-5 million years) little is known about the stability of the ecological interactions among these taxa.

Because species live in complex, interdependent web of interactions, it has proved difficult to understand the effects that environmental changes have on ecological systems. Abiotic and/or biotic change can differentially affect species in a community, because each species responds differently to changes in their environment. For instance, observations in modern communities have found that weak competitors are often superior dispersers and the immigration of predators is often delayed compared to that of their prey species. Ecologists have developed a ‘community module’ approach to track community response to climate change (Gilman et al 2010). This method simplifies the complexity of community structures by focusing on a distinct set of strong and common ecological interactions to help understand the dynamics of the system as a whole.

We propose that this approach can be applied to certain ecological interactions in the fossil record, particularly antagonisms and mutualisms that leave a diagnostic trace fossil record. The rich trace fossil record of the Hamilton Fauna provides us with the unique opportunity to examine these types of ecological interactions in the Middle Devonian. The ‘community module’ approach provides a conceptual framework for understanding the intensity and range of variability of ecological interactions through space and time during this well-defined time interval.

Gilman et al. 2010. A framework for community interactions under climate change. Trends in Ecology and Evolution 25(6):325-331