The demographic meanings of the classical population growth models of ecology

Abstract

Ecological populations consist of individual organisms that experience birth, growth in body size during at leat part of the lifespan, and finally death. These basic facts have inspired the development of much demographic theory during the last 75 years. Keytitz (1968), Pollard (1973), Charlesworth (1980), and Nisbet and Gurney (1982) review much of the classical theoretical treatment originally devised by Sharpe and Lotka (1911), McKendrick (1926), Leslie (1945, 1948), von Foerster (1959), Lelkovitch (1965), Sinko and Streifer (1967), and others. Assorted refinements have been provided by Weiss (1968), VanSickle (1977), Van Straalen (1982), Law (1983), Hughes (1984), and Kirkpatrick 1984). The major results of this work have proven sufficiently broadly useful in field ecological studies that they appear routinely in introductory ecology textbooks. The strength of this theory is its relatively detailed description of numerical changes in the kinds of organisms (with individuals classified by age, size, and possibly other characteristics) that comprise a population and how organisms of each kind contribute to further population changes through births, deaths, and transitions from one kind to another. This detailed accounting has provided the foundation for Caswell’s (1982a-d