XVI International Botanical Congess

Phylogenetic and experimental studies of Dalechampia (Euphorbiaceae) indicate that the unusual system of rewarded pollinators with terpenoid resins, which pollinating bees use in nest construction, originated by modification of a pre-existing resin defenses of staminate flowers. Another exaptation is evidenced in advanced clades that defend fruits or leaves by resins that evolved from the reward system. Many bee-pollinated species of Clusia (Clusiaceae) also secrete resin towards and defend tissues with latex. C. grandiflora reward resins contain benzophenones which are highly toxic to bacterial pathogens of the honeybee. Structurally different benzophenones occur in latex, suggesting that resin has a biogenetic link to latex. Bioactivity in latex components is absent or markedly reduced compared to resin components. This is consistent with resin reward chemistry having evolved from latex under selection by apids for increased bactericidal activity.