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Introduction to Populations

Author(s): Deanne Erdmann, MS

Survivorship in Populations

Survivorship curves are graphic representations of the age structure of a given population. They are used to predict the future growth of the population. Type I curves reflect relatively low death rates early in life and through midlife, with a sharp increase in death rate among older-age groups (e.g., humans). Type II curves illustrate a fairly even mortality rate throughout the life span of the organism (e.g., birds). Populations with high death rates early in life followed by a sharp decline of death rates for the survivors are represented by Type III survivorship curves (e.g., fish and many insect populations).