Abstract
1. Biological diversity is affected by a multitude of evolutionary and ecological processes, but diversity patterns are quite universal across taxa; diversity generally increases towards low latitudes and towards environments characterized by high temperature and energy availability.
2. The Metabolic Theory of Ecology (MTE) assumes that diversity is affected both by amount or supply rate of resources which positively affects total number of individuals, and by the positive effect of temperature on diversification rates. Although these assumptions are reasonable, this theory has several conceptual problems and the empirical patterns support only some of its predictions.
3. Species richness does not seem to be strongly affected by the total number of individuals.
4. Diversity patterns are certainly affected also by processes which are not accounted for by the MTE, most importantly range dynamics associated with the evolution of species climatic tolerances, which is affected by the level of the conservatism of ecological niches of species.
5. However, temperature appears as the most important driver of diversity patterns, possibly due to temperature-dependence of most biological processes.