From biodiversity and ecosystem functioning to the roots of ecological complexity

Biodiversity is monophyletic: life started with a single species. Biodiversity evolved, becoming more and more complex, by a process that went through many patterns of diversification and that is still running. Biodiversity is not teleological, it did not evolve at the present stage to make a proper world for us, or to make ecosystems function; ecosystems functioned also at the dawn of life, when diversity was very low. Ecology and evolution are strictly linked, and both are historical disciplines that involve non-linear systems with a clear chaotic development, with the co-existence of strong constraints (in both form and function) and powerful contingencies (like those that caused the mass extinctions of the past). Historical predictions can only be weak, and can be formulated only when trends are identified (i.e. the attractors of chaotic systems). Modern ecology discarded natural history, setting quantitative goals that forced it to remove quality from its vision of complexity. This attitude led to enormous conceptual advances that are starting to show their limits. The identification of trends, set by constraints/attractors, and of deviations from them, due to contingencies, is an ambitious and practicable goal for mature ecology