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Measuring and Modeling Population Change SBI4U. Demography The statistical study of the processes that change the size and density of a population through.

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Presentation on theme: "Measuring and Modeling Population Change SBI4U. Demography The statistical study of the processes that change the size and density of a population through."— Presentation transcript:

1 Measuring and Modeling Population Change SBI4U

2 Demography The statistical study of the processes that change the size and density of a population through time. Why is Demography important? Used to predict the growth of a population or develop plans to protect endangered species. What are some factors that would change the size and density of a population through time? Natality (birth rate), mortality(death rate), immigration, and emigration are factors that generate changes in a population  population dynamics How do ecologists record/follow these changes? Routine sampling What are some types of sampling an ecologist would use?

3 Life Tables What are some techniques demographers use? Life table – summarizes the demographic characteristics of a population How are Life Tables created? Cohort

4 Population Dynamics Fecundity is the potential to produce offspring in one lifetime Varies from species to species What conditions could effect a population’s fecundity? Environmental Other regulating factors: Generation time Sex ratio Parental care

5 Survivorship curves Used to depict data collected on a life table Displays the survival of individuals in a population over the lifespan of the species. There are 3 general survivorship curve types: I = many survive childhood and die of old age Large animals with few young and high parental care Long gestation periods II = consistent birth and death rate Short gestation period, usually prey for larger animals, feed on Type III III = high childhood mortality Large number of offspring produced

6 Carrying Capacity The carrying capacity is the maximum number of organisms that can be sustained by available resources for a specific amount of time. K is the carrying capacity Determined by factors in the environment

7 Calculating Changes Open populations Uses the equation above Closed populations No immigration or emigration Biotic potential The maximum rate of population growth under ideal conditions

8 Population Growth Models Geometric growth Geometric growth is growth where organisms reproduce at fixed intervals at a constant rate Growth is intermittent See example on page 663 Exponential growth Exponential growth is growth where organisms reproduce at continuously at a constant rate Growth is continuous See example on page 665

9 Modeling Logistic Growth Lag phase Log phase Stationary phase

10 Credits http://commons.wikimedia.org/wiki/File:CarryingCapacity_2.j pg http://commons.wikimedia.org/wiki/File:CarryingCapacity_2.j pg http://commons.wikimedia.org/wiki/File:Survivorship_Curves. jpg http://commons.wikimedia.org/wiki/File:Survivorship_Curves. jpg http://en.wikipedia.org/wiki/File:Population_curve.svg


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