Energy availability, spatio-temporal variability and implications for animal ecology

Abstract

Aim: Global environmental change, through anthropogenic activities and climatic changes, is promoting broad-scale alterations to energy availability across the world's ecosystems. However, spatio-temporal variation in available energy is a key driver of animals' life histories, movement patterns and abundance, thus shaping the global distribution of individuals and species. As such, there is an increasing need to understand how and where changes to energy availability will produce the greatest impacts on animal ecology, and ultimately on the distribution of biodiversity. Location: Global. Methods: We compiled data from the published literature where attempts (n = 171) have been made to find linkages between prevailing energy availability (primary productivity, indexed by the Normalized Difference Vegetation Index; NDVI) and ecological parameters (abundance, distribution and life histories) for bird and mammal species. We extracted information on trophic level (diet) and body mass for the species considered in these studies, as well as long-term site-specific average energy availability, and levels of seasonality and interannual stability (all indexed using NDVI-based metrics as proxies). We conducted a GLMM analysis to assess how these variables may structure the variability in the reported linkages between prevailing energy availability and the considered ecological parameters. Results: Our analysis revealed that the strength of the reported relationships between metrics of prevailing energy availability and ecological parameters was highest in environments with high long-term interannual stability in available energy, and for larger, non-carnivorous animals. Importantly, we found no support for an influence of long-term site-specific average energy availability on the strength of these relationships. Main conclusions: Overall, our results support the hypothesis that temporal stability in energy availability is a key factor controlling animal ecology over total available energy itself. These results may have some important implications for the future health and conservation requirements of currently largely stable regions under global environmental change.