ABSTRACT
The life history of an animal is the sequence of morphogenetic stages from fertilization of the egg to senescence and death, which incorporates the probabilistic distributions of demographic parameters of an individual's population as components of the life-history phenotype. At the population (or species) level, and in the context of ectothermic vertebrates, Dunham et a l (1989) have defined a life history in terms of a heritable set of rules that govern three categories of allocations: (1) allocation of time among such activities as feeding, mating, defense, and migration; (2) allocation of assimilated resources among growth, storage, maintenance, and reproduction; and (3) the mode of "packaging" of the reproductive allocation. An application of such an allocation-based definition in the study of salamander life histories was provided by Bernardo (1994). Implicit in the definition is the condition that life-history traits have a heritable basis; average plasticity in any trait reflects the average reaction norm, or the range in phenotypes expressed by a given genotype, averaged for all genotypes, over the range of environments experienced by all members of the population (Via 1993).
