EVOLUTION AND POLLINATION OF MADAGASCAN AND AFRICAN DALECHAMPIA

We studied the pollination ecology of endemic Madagascan species and m ainland African species of a pantropical genus of plants, Dalechampia (Euphorbiaceae). Comparison across continents allows us to understand how floral characteristics and ecological relationships evolve as a ta xon disperses through space and time. By combining pollination and phy logenetic studies we generated 2 competing evolutionary hypotheses to explain the unusual ecology of Madagascan Dalechampia: Madagascan Dala champia evolved from primitive New World species before the resin-rewa rd system originated; or they evolved from resin-secreting African spe cies and secondarily (and rapidly) lost resin secretion. The data supp orting each hypothesis are nearly balanced. In either case, however, t ight linkage between distribution and pollination ecology suggests rap id evolutionary response to the pressures of a environment.