Beetle pollination of two species of Zamia: evolutionary and ecological considerations

Abstract

Two species of cycads in Florida are invariably pollinated by beetles. The native Florida Zamia pumila L. is pollinated by a snout weevil, Rhopalotria slossoni Schaeffer, and a clavicorn beetle, Pharaxonotha zamiae Blake. An introduced cycad, Z. furfuracea L. fil., is pollinated by the snout weevil, R. mollis Sharp, apparently introduced from Mexico along with its host. Observations and experiment show that zamias are dependent upon pollinating beetles for their reproduction, and, in turn, the pollinating insects are dependent upon the cycads for brood places, food and shelter. The two cycads have evolved similar “rewards” which function as pollinator attractants. The importance of these coevolutionary inter-relationship for the ecology and conservation of these cycad species is unquestionable. Neither the insects nor the cycads are separately capable of long term survival in nature, and unless both are protected and conserved, wild populations of Zamia are in jeopardy.