Predicting natural mortality rates of plants and animals.

Understanding the factors that control the mortality rates of species in their natural environments is important for understanding the structure and dynamics of populations, communities and ecosystems. Here, we test a model of natural mortality that yields explicit, quantitative predictions based on the constraints of body size and temperature on individual metabolism. Extensive field data from plants, invertebrates, fish, birds and mammals indicate that much of the heterogeneity in rates of natural mortality can be predicted, despite the many extrinsic sources of mortality in natural systems. These results suggest that common 'rule(s)' govern mortality rates in ecological communities for organisms as diverse as plants and animals.