Physiological Ecology of Fruits and Their Seeds

Abstract

The function of an immature fruit is to add to the photosynthate pool and to protect the developing seed (see Chap. 17, this Vol.). Once ripe, the fruit puts the seed in the appropriate dispersal agent(s) and keeps it away from seed predators and inappropriate" dispersal agents". It is the selective pressures associated with such a diverse and often conflicting set of demands that have generated fruit physiology. To this date, the examination of fruit and seed physiology has been almost entirely directed at either the use of these structures as human food or as esoteric anatomical objects (KOZLOWSKI 1972, 1973; ROTH 1977). Here, instead of repeating the descriptive information in the above three reviews, I dwell on why fruits and seeds have the traits they do, much in the spirit of three recent reviews (JANZEN 1971, 1977 a, 1979a). The physiological traits of seeds are generated by sibling rivalry, need for protection during development and dispersal, parental resource allocation considerations, dispersal agent traits, and resources needed by the young seedling. In short, a seed is a one-move time-consuming recruitment attempt by the parent plant and the fruit is its accomplice.