Patterns of parental investment,dispersal and size among coral-reef fishes

Synopsis Coral-reef fishes have been selected to produce propagules for dispersal because they live in a patchy environment, and the adults cannot migrate between patches. For large species (>100 mm SL) and widely separated patches, numerous propagules are needed, often with specialized pelagic intervals. Individuals of small species are confined to portions of the reef. They are unable to produce enough eggs for effective longrange dispersal, and so they keep their vulnerable eggs and young out of the plankton until they are well developed enough to seek out and settle onto the appropriate habitat before dispersing.Guarded demersal eggs, requiring a greater individual investment by the small short-lived species, further reduces their individual fecundity. These costs to fecundity, and the reduction in vagile young appear to account for the lack of postzygotic investment in larger longlived species.All coral-reef fishes are selected to disperse, usually with a young planktonic propagule interval. Both large and small species produce a mixed outcome, with some propagules returned to, or retained at the home reef, while others disperse more widely. The smaller the species the greater the proportion of propagules retained.