Chapter 26 - Chapter 26 Population Growth and regulation...

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Chapter 26: Population Growth and regulation: Case Study: The Mystery of Easter island: o On Easter island is has been proven that in ancient times there was vast vegetation that allowed for a thriving society, but as they used up the resources the society died along with the resources—reasons for this can be seen in this chapter. 26.1: How does population size change? o Ecology—the study of interrelationships between living things and their nonliving environment. o Abiotic-non living components of an ecosystem—soil, water, weather, etc o Biotic—living components of an ecosystem o Ecosystem—includes everything, both living and non living with a defines area o Community—all interacting populations of organism form the community A population consists of all the members of a particular species that live within an ecosystem In contrast to most nonhuman species, the global human population has exhibited steady growth for centuries. Birth, death, and migration in and out are the three factors that determine whether and how much populations have changed Population growth occurs when the number of births plus immigration exceeds the number of deaths plus emigrants. Birth and death rates are the primary factors that influence populations growth. Biotic Potential is the maximum rate at which the population could increase, assuming ideal condition that allow a maximum birth rate and minimum death rate. Environmental resistance refers to the curbs on population growth that are set by the living and nonliving environment. o Biotic potential can produce exponential growth The birth rate and death rate are often expressed as the number of births per individual during a specific unit of time, such as a month or a year. The growth rate of a population is a measure of the change in population size per individual per unit of time.
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This pattern of continuously accelerating increase in population size is called exponential growth. Several factors influence biotic potential: The age at which the organism first reproduces The frequency at which reproduction occurs The average number of offspring produced each time the organism reproduces The length of the organisms reproductive life span The death rate of individuals under ideal conditions If each woman bears 3 children in her early teens, the population will grow faster than if a woman in her 30s had 5 children.
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