23 September 2011
Vol 333, Issue 6050

About The Cover

Cover image expansion

COVER Tropical tree species in Soberania National Park, Panama. Differences in species composition across locations (β diversity) generally increase at low latitude and elevation, such that the β diversity of many clades peaks in lowland, tropical areas. Kraft et al. show that this trend is more likely driven by differences in the size of species pools than by differences in community assembly processes in temperate versus tropical systems. See p. 1755 Image: Christian Ziegler, Smithsonian Tropical Research Institute