Ecosystem engineering, regime shifts and the rise of animals.

The term 'ecosystem engineering' refers to biotic processes that modulate the availability of resources to other species. These processes thus modify, maintain or create habitats and impact the abundance and diversity of species within ecosystems. In turn, the study of ecosystem engineering in the fossil record is leading to a re-evaluation of the influence of organisms on the deep-time evolution of Earth-system structure and function. With this comes a growing recognition that biological forces may be key drivers of major transitions in Earth history. There are two crucial questions: first, have new ecosystem engineering processes emerged randomly throughout geologic time, or are they clustered? Second, to what extent has their emergence driven episodes of evolutionary radiation or extinction? Here, we address these questions through the lens of the Ediacaran-Cambrian transition (∼575-530 million years ago) - an interval that witnessed the rapid rise of animals, following nearly four billion years of microbial dominance. We propose that an engineering regime shift occurred in the late Ediacaran that gave rise to new rules of community assembly, new ecological niches, and altered macroevolutionary trajectories. We argue that the recognition of ecosystem engineering regime shifts may help us not only to understand other key intervals in the Phanerozoic, but also to project the future of ecosystems under human influence.