Energy and geographic variation in species richness

Understanding the latitudinal gradient in species diversity presents ecology with one of its greatest challenges. Despite the complexities that must be involved, the "energy hypothesis" may provide a parsimonious explanation for much of the gradient. However, there are a number of unresolved issues related to the energy hypothesis that need to be addressed, including (1) the relationship between energy and other determinants of diversity and how to distinguish them, (2) which of two versions of the energy hypothesis, the "productivity hypothesis" or the "ambient energy hypothesis" may apply to different taxa, (3) the relative roles of currently operating climatic factors and historical forces, (4) the probability that different factors operate in different latitudinal zones. (5) possible scale dependence of energy-diversity relationships, and (6) the most appropriate statistical methodology for testing the hypothesis. The proposed working group will address these issues, with the goal of providing a rigorous statement of what the energy hypothesis claims and providing a standardized format for the generation of data to test it. A further goal is to use the new format to generate a data base comprising all existing data related to the energy hypothesis. Finally, we will analyze this database to determine the current state of the hypothesis and identify areas requiring additional research. Our general goal is to convert what is currently a haphazard approach to testing geographic variation in species diversity into a systematic search for underlying causes.