Natural Population and Community Structure and Dynamics: the “Supply — Side Ecology”, Theory and the Field Data

Abstract

A peculiar field of ecology is the study of natural population age structure and dynamics (demography). This field is highly relevant for conservation and management of overexploited or endangered species. In the last years a new approach to population dynamics was developed, the “supply-side ecology”, i.e. the study of the process supplying new individuals to natural populations (recruitment). This branch of ecology was carried out mainly by marine ecologists. Several models, based on the clues of density-dependence (the density of adults or new settled individuals limits recruitment) or recruitment dependence (recruitment fluctuates according to larval supply) were developed. Some of these models and experimental field data are here examined and discussed. In several cases density-dependent models, so familiar to mathematicians modeling ecological systems, do not represent the complex reality of marine population dynamics.