Info

Age (as fraction of lifespan)

Age Structure

The distribution of individuals among different ages in a population is called age structure. Age structures are often presented in graphs, as in Figure 19-4. Many important population processes vary with age. In humans, very old individuals do not reproduce. If human populations have a high percentage of young individuals, they may have a greater potential for rapid growth.

Patterns of Mortality

The mortality data of different species tend to match one of three curves on a graph, as shown in Figure 19-5. These curves are called survivorship curves because they show the probability that members of a population will survive to a certain age. In humans or elephants, for instance, the likelihood of dying is small until late in life, when mortality increases rapidly. This pattern of mortality produces the Type I survivorship curve. For other organisms, such as some species of birds, the probability of dying does not change throughout life, giving a linear, or Type II, survivorship curve. Finally, many organisms are very likely to die when young. If an individual survives this early period, however, it has a good chance of surviving to old age. This type of survivorship curve, called Type III, is characteristic of animals such as oysters and salmon, and of many insects.

Sirens Sleep Solution

Sirens Sleep Solution

Discover How To Sleep In Peace And Harmony In A World Full Of Uncertainty And Dramatically Improve Your Quality Of Life Today! Finally You Can Fully Equip Yourself With These “Must Have” Tools For Achieving Peace And Calmness And Live A Life Of Comfort That You Deserve!

Get My Free Ebook


Post a comment