Why the World Has So Many Species, and What Can Be Done to Prevent Their Extinction

Principal Investigator(s): 

David Tilman

The most unique feature of earth is the existence of life, and the most unique feature of this life is its incredible diversity. Indeed, about 10 million species of plants, animal and microbes, all thought to be descended from a single ancestral species, now inhabit the earth.  As life on earth diversified, new species tended to coexist with existing species.  Ecological theory predicts that this coexistence must mean that there are tradeoffs among species. Such tradeoffs would mean, for example, that a plant species that was a better competitor for water would necessarily be a poorer competitor for a different limiting factor, such as soil nitrogen. My research will test this hypothesis by examining patterns of coexistence or displacement reported from the fossil record for plants, mammals, birds, mollusks and other types of organisms. This research is designed to help us better understand why the world has so many species.

Massive human-driven destruction of native ecosystems is now starting to threaten many species with extinction. The other aspect of my research will explore what may lie ahead during the upcoming 50 years. During that period global population is projected to increase by 50% and the consumption of various goods and services by a typical person is projected to increase by 140%. These two forces are projected to cause global energy and food demand to double within the next 40 to 50 years. Much of the demand for food may be met my clearing remaining lands for agriculture and for production of biofuels. I will compile and analyze a global data set to quantitatively project such impacts on land conversion and on biodiversity for the coming 50 years, and also seek alternative solutions that would meet our demand for food and energy with lower impacts on biodiversity.