The Self-Adjustment of Populations to Change

To demonstrate how populations may accommodate themselves to changed conditions, and so maintain themselves in being, I shall devote much of this address to discussing the results of laboratory experiments with the Australian sheep-blowfly, Lucilia cuprina Wied. It is true that the particular mechanisms of adjustment revealed are replaced by other mechanisms in many natural populations, but this would be equally true were any other kind of animal studied, whether in the laboratory or in the field. The fact that results obtained with laboratory populations can seldom be regarded as directly applicable to field populations in general is due to the existence of at least a dozen major systems of population regulation, and to the great diversity of influences which cause each population to present a somewhat different problem from all others. However, abundant evidence is provided by both field and laboratory studies showing that the populations of many...