ABSTRACT:

The aim of this study was to evaluate the differences between two flowering populations of Dieffenbachia longispatha; one on Barro Colorado Island, Panama and the other at La Selva Biological Station, Costa Rica. The Barro Colorado population exhibited green spathes and 10-15 loosely packed bright orange female florets in the lower spadix zone, compared to the La Selva populations, which had slightly larger yellow-green spathes and 40-50 densely packed yellow female florets in the lower spadix zone. Other differences included floral odor, which was sweet and spicy in the Barro Colorado population and rancid smelling on La Selva plants, together with numbers, species and timings of beetle visitors. On Barro Colorado the dominant beetle visitors were Cyclocephala gravis and Cyclocephala sexpunctata compared to Cyclocephala amblyopsis and Cyclocephala gravis at La Selva. In conclusion, the effects of selection by the local beetle populations in each locality appears to have led to the evolution of different sub-species of D. longispatha on Barro Colorado Island in Panama and at La Selva Biological Station, Costa Rica.