INDITEK: A model to understand the emergence of marine biodiversity hotspots in the last 500 million years

Life originated in the sea about 4 billion years ago and, for the first 3.5 billion years, it was exclusively microscopic. Something happened early in the Cambrian period that made multicellular life to thrive, giving rise to the spectacular biodiversity that has been this planet's hallmark for the past 500 million years. This staggering increase in diversity has raised a fundamental question among evolutionary ecologists: are there limits to the diversity of life? Some scientists say that global diversity increases to an equilibrium point or saturation level that is determined by the system’s carrying capacity. Alternatively, others claim that biodiversity is well below the saturation level and thus we can ignore the existence of any limit. These contrasting views have been fueled by interpretations of the fossil record which is severely biased in space and time. To theoretically test these contrasting views, we have developed a regional diversification model. In the model, we let 1 genus to diversify everywhere in the global ocean from 500 million years ago until present according to a model of paleogeography that constrains the diversification time and a paleo Earth System model that constrains the diversification rate as a function of seawater temperature and food supply. By externally imposing mass extinctions, we explore how the oceans filled with life. The regional model fits surprisingly well global fossil diversity curves and modern biodiversity distributions. According to the model, the ocean is far from saturation except for in the biodiversity hotspots, regions of extraordinarily high levels of diversity, which evolved under prolonged conditions of Earth system stability and maximum continental fragmentation. The model allows us to recreate many things, such as the history of biodiversity hotspots and the dynamics of the latitudinal biodiversity gradient.