Botanist and Ecologist: My favorite science experience is finding out what causes different species to live in different areas worldwide. One of the most interesting questions is what causes the “latitudinal diversity gradient.” Over 200 years ago, scientists noticed that many different species live in and near tropical regions. In habitats closer to the poles, however, fewer different species are found. Causes of the latitudinal diversity gradient are not well known. In my research, I explore how evolutionary processes and ecological factors interact to influence global patterns of species diversity.