The paleotropics harbor many biodiversity hotspots and show many different species richness patterns. However, it remains unclear which factors are the most important in directly shaping richness patterns among regions in the paleotropics (i.e. diversification rates, colonization times, dispersal frequency). Here we used Cycadaceae as a model system to test the causes of regional richness patterns in the paleotropics. Specifically we tested the roles of dispersal frequency, colonization time, diversification rates, and their combined role...