Life-history strategies

Abstract

Its life table encapsulates in a quantitative form the life-history pattern of a population. Fishes have evolved a diversity of life-history patterns (Breder and Rosen, 1966). In some species, sexual maturity is reached within a few weeks of hatching, in others only after several years. Some species are semelparous, others iteroparous. Some have short life spans, others may live for many decades. Even within a species, there may be major variations in the life-history patterns shown by different populations. Intraspecific differences in migration, growth, age at first reproduction, life span and fecundity are described in earlier chapters. What are the environmental factors that favour the evolution of a particular life-history pattern? How will a life-history pattern change as environmental conditions change? This second question is relevant to the effects of fishing and pollution which constitute new causes of mortality or impose other adverse effects on a population.