Coevolutionary Patterns in Central American Bignoniaceae

Abstract

600 species of th J family Bignoniaceae are mostly large-flowered, winddispersed, woody, tropica] plants.Division of the family into three major tribes Tecomeae, Bignonieae, and Crescentieae-is based primarily on fruit morphology.In the nootropics the majority of the species are lianas, virtually all belonging to the Bignonieae.The neotropical Tecomeae and Crescentieae (excluding Schlegelia) are arborescent.Bignoniaceae is one of the most important families of woody plants and the most important family of lianas in the Central American forest ecosystems I have studied.This is true no matter whether diversity, frequency of occurrence, or density is chosen as an index of importance (Gentry, 1972, and in preparation).The revolutionary patterns found in such an important family are clearly very important to understanding the evolution of the adaptive strategies of the animals which interact with these plants.Several aspects of bignon biology indicate long histories of coevolution with various groups of animals.I will note separately some evolutionary diversifications in the family related to interactions with herbivores, frugivores, and pollinators. Vkgetative InteractionsNon-reproductive interactions of bignons with animals have led to the development of different kinds of defensive mechanisms against herbivores.Chemical defenses in the Bignoniaceae appear to be very effective.In the field the level of herbivore damage to bignons is generally low, and even when dried plants of this family are remarkably resistant to insects (Lewis, 1971).The wood of this family is much prized for construction because of its great durability.Beams of Tabebuia wood, known to have been exposed to the elements for 400 years, are still free of decay (Record & Hess, 1940).Tabebuia guayacan is one of the most durable woods of Panama with respect to terrestrial organisms, and the lew sound trees remaining from the forest inundated over 50 years ago by Gatun Lake are mostly T. ^uayacan (Southwell & Bultman, 1971).Resistance to herbivores and wood-destroying insects is related to the presence of large quantities of lapachol in many species of the family (Sandermann & Dietrichs, 1957; Gentry, 1967).Other genera are presumably protected by such unidentified chemical