The number of species that can exist on Earth depends on how the environment changes, according to new research led by the University of Southampton. By analysing the fossil record of microscopic aquatic creatures called planktonic foraminifera, whose fossil remains now resemble miniaturised popcorn and date back millions of years, the research provided the first statistical evidence that environmental changes put a cap on species richness. Dr Ezard added: "We used mathematical models to reveal how environmental changes influence both the rate of diversification among species and how many species can co-exist at once. Our results suggest that the world...