IS DISPERSAL OF FISH EGGS, EMBRYOS AND LARVAE AN INSURANCE AGAINST DENSITY DEPENDENCE

Dispersal of eggs, embryos and larvae appears to be an effective mechanism for maintaining the densities of fish larvae at sea below levels at which competition for food becomes a critical survival factor. A hypothesis that competition is the selective agent for the evolution of dispersal, also involving unfavourable transportation as a trade-off of dispersal, is proposed. The validity of this hypothesis is investigated by seeking for adaptive connections between the dispersal or retention tendencies and the ecological or biological properties of the species.