RELATIVE RISKS OF MICROBIAL ROT FOR FLESHY FRUITS - SIGNIFICANCE WITH RESPECT TO DISPERSAL AND SELECTION FOR SECONDARY DEFENSE

This chapter discusses the relative risks of microbial rot for fleshy fruits, their vertebrate dispersers, and the parameters necessary to evaluate selection pressures for secondary chemical defense. The hypotheses and predictions presented in the chapter elucidate the evolutionary significance of secondary chemicals of ripe fleshy fruits, and their potential effects in mediating plant-frugivore-fungus interactions. The chapter concerns the defense of ripe fruit from microbial fruit-rot agents, and the degree to which characteristics relating to seed dispersal can be used to predict patterns of secondary chemical defense. Interspecific variation in chemical and physical characteristics suggests that fruits may vary in susceptibility to microbes, seed predators and pests, and thus in their response to selective pressure for the evolution of secondary defenses. Several predictions concerning variation in selection pressure for antifungal defense, with particular reference to fruits and fruit-rot fungi of eastern North America are generated. These predictions are based largely on assumptions of how plants and microbes should react to various selective pressures, and are therefore subject to re-evaluation if certain assumptions are incorrect, or if certain factors are overriding in importance. © 1992 Academic Press Limited