Macro perspectives on disease and ecological change
Fundamental questions about infectious disease involve spatial and temporal scale: When does a disease start, where has it emerged, will it spread from point A to point B in a rapid or slow time frame, did a disease originate in one species in a clade because it lives in one region or has a certain biology or results from its long, unique phylogenetic history? Each of these questions benefit from considering a large scale, especially with regard to modern ecological changes in relation to climate, economics, extinction, habitat loss and human intervention. The science of Macroecology explicitly approaches questions from broad scales and focuses on emergent statistical processes to find consistent patterns and processes, thus identifying similar causal mechanisms. Although Macroecology was only christened about 20 years ago, the science has developed rapidly to already establish rules of species area relationships, latitudinal gradient of species richness, the relationship of body size and metabolic rate, species-abundance distributions, species body size-size distributions. Many of these rules are useful for generating new hypotheses for the above fundamental questions.
Macroecology has been most successful and exciting when rigor is applied to: data collection, statistical methodology, repeated and consistent patterns observed across independent taxonomic groups, iterative hypothesis testing and, overall, macro patterns are checked and verified against micro patterns. Interesting empirical results to date suggest that evolutionary history, hotspots of species richness associated with areas climate change, and various host biological traits such as body size, geographic range area, and population density are significant correlates of disease. As with conservation efforts to curtail the 6th mass extinction, development of a new macroecological framework for predicting global patterns of disease emergence in the context of profound ecological change is of utmost importance.