The symbiotic relationship between fig plants (Ficus species) and their tiny pollinating wasps has fascinated biologists since classical times, when Aristotle and Theophrastus mentioned the connection between an abundance of wasps and a good fruit set in the common fig, Ficus carica L. The complex reproductive biology of Ficus species in general and of F. carica in particular has been described many times, and we will not repeat here details of floral morphology, pollination or insect structure and behavior (see Condit, 1947; Valdeyron, 1964, 1967; GaUl and Eisikowitch, 1968a, 1968b, 1969, 1974; Ramirez, 1969, 1970, 1974, 1977; Hill, 1967; Galil, 1973, 1977; Storey, 1955, 1975, 1976; Galil and Neeman, 1977). After a description of some general features of the symbiotic relationship between Ficus species and wasps, we will concentrate on the differences between male and female plants of F. carica in their sexual performance and in the phenology of development of the syconia. The evolutionary origin of the separate sexes in F. carica and related species and the selective forces responsible for the characters of the various crops produced by the two sexes are considered in detail for the first time

The pollinators of the approximately 1000 species of Ficus are symbiotic wasps of the family Agaonidae (order Hymenoptera). The symbiosis is highly specific; Grandi (1929), Wiebes (1963), Hill (1967) and Ramirez (1970, 1974)have shown that in the great majority of investigated species in both the Old and New Worlds, each Ficus species is pollinated by one agaonid wasp which is confined to that species. The pollinator of F. carica, for example, is Blostophaga psenes L. In a few cases, one fig species hosts two wasp species or a wasp pollinates a few closely related Ficus species. The relationship between the reproduction of the tree and that of the insect is mutually obligatory, since pollen can be transferred to the enclosed female flowers only by the pollinator, and the wasps depend on the figs for their reproductive sites.