This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
One of the major unanswered patterns in ecology is the latitudinal gradient of species diversity from the tropics to the poles. This project will develop a comprehensive explanation for this and related patterns in the distribution and abundance of plants and animals based on a novel synthesis of ecological and evolutionary theories that challenges generally accepted ideas. The underlying theory is that the evolution and distribution of plants and animals have been shaped by the geometry of the solar system. More solar energy reaches the Earth's surface in the tropics, resulting in a higher abundance and faster growth of plants and animals. This idea has shaped much of current ecological and evolutionary theory. However, recent analyses of the actual patterns of plant growth and animal abundance suggest that the tropics are not the center of growth and abundance. High temperatures and rainfall cause rapid dissolution and leaching of mineral nutrients from the soils. Thus, many tropical soils are extremely low in nutrients, imposing extreme limitations on plant growth. The distinctive feature of tropical plants and animals may actually be low growth rates and population densities, while the temperate zones have higher productivity and greater abundance of plants and animals per species. Since most ecological and evolutionary hypotheses explain the high diversity of the tropics on the basis of high productivity, many of these hypotheses may have to be rejected. The alternative hypotheses are based on the positive effects of low productivity on ecological and evolutionary processes that affect diversity, along with the negative effects of high productivity on these same processes. This project has the potential to revolutionize our understanding of the distribution, abundance, and diversity of life on our planet. Increasing scientific and public concern about the ongoing extinction crisis and climate change has generated increasing interest in how natural ecosystems function. A new explanation of global patterns of species diversity is likely to receive a great deal of scientific attention and contribute to large-scale management decisions related to biodiversity. This project will enable continuing productivity by the PI and engagement of undergraduate and graduate students, including underrepresented minorities, in these important issues.
