What type of survivorship curve

Type I describes the situation in which mortality is concentrated toward the end of the maximum lifespan. It is perhaps most typical of humans in developed countries and their carefully tended zoo animals and pets. Type II is a straight line that describes a constant mortality rate from birth to maximum age.

It describes, for instance, the survival of seeds buried in the soil. Type III indicates extensive early mortality, but a high rate of subsequent survival. This is typical of species that produce many offspring.

Few survive initially, but once individuals reach a critical size, their risk of death remains low and more or less constant. This appears to be the most common survivorship curve among animals and plants in nature. Figure 4. Type I convex - epitomized perhaps by humans in rich countries, cosseted animals in a zoo or leaves on a plant - describes the situation in which mortality is concentrated at the end of the maximum lifespan.

Type II straight indicates that the probability of death remains constant with age, and may well apply to the buried seed banks of many plant populations. Type III concave indicates extensive early mortality, with those that remain having a high rate of survival subsequently. This is true, for example, of many marine fish, which produce millions of eggs of which very few survive to become adults. After Pearl, ; Deevey, These types of survivorship curve are useful generalizations, but in practice, patterns of survival are usually more complex.

Murie, A. The wolves of Mount McKinley. Aging and Its Demographic Measurement. Allee Effects. An Introduction to Population Growth. Density and Dispersion. Introduction to Population Demographics. Population Dynamics of Mutualism.

Population Ecology Introduction. Population Limiting Factors. The Breeder's Equation. Global Atmospheric Change and Animal Populations. Semelparity and Iteroparity. Causes and Consequences of Dispersal in Plants and Animals. Disease Ecology. Survivorship Curves. The Population Dynamics of Vector-borne Diseases. Citation: Rauschert, E. Nature Education Knowledge 3 10 How long do we live? How long do individuals in other species live?

Do most individuals die young or live to ripe old ages? Survivorship curves visually answer these demographic questions. Aa Aa Aa. Figure 1. Figure 2. Pseudemys scripta exhibits Type II survivorship in individuals ages years data from Gibbons and Semlitsch Ovis dalii have a Type I survivorship data from Murie Human Survivorship Patterns.

Figure 6. References and Recommended Reading Flood, N. Pearl, R. The Rate of Living. New York, NY: Knopf, Share Cancel. Revoke Cancel. Keywords Keywords for this Article. Save Cancel. Flag Inappropriate The Content is: Objectionable. Flag Content Cancel. Email your Friend. Submit Cancel.

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