Reproductive constraints and the evolution of life histories with indeterminate growth

A prominent feature of comparative life histories in fish (and other indete rminate growers) is the approximate invariance across species of certain di mensionless numbers made up from reproductive and timing variables. The two best known are the age at maturity (a) divided by the average adult lifesp an (E), and the proportion of a body mass given to reproduction per year (c ) multiplied by E. This article uses evolutionary life-history theory for n ongrowing populations to predict the numeric value of these numbers for fis h and lizards, with several new implications for the dynamics of ontogeneti c development.