Chapter 5 Populations - PowerPoint PPT Presentation

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Chapter 5 Populations

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Chapter 5 Populations Biotic Potential: The size a population would reach if all offspring were to survive and reproduce Conditions have to be ideal- enough food and ... – PowerPoint PPT presentation

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Title: Chapter 5 Populations


1
Chapter 5 Populations
2
Biotic Potential The size a population would
reach if all offspring were to survive and
reproduce
3
  • Conditions have to be ideal- enough food and
    living space
  • How many children could a human female have in
    her lifetime?

4
Population Density- Number of individuals in an
area
  • What Determines density and distribution?

5
  • Geographic Distribution- range- the area the
    population inhabits

6
Population Growth
  • Affected by
  • -Births
  • -Deaths
  • -Immigration- entering an area
  • -Emigration- leaving an area

7
  • Populations increase if births exceed deaths and
    immigration exceeds emigration

8
Exponential Growth
  • Exponential Growth occurs when the individuals in
    a population increase at a constant rate
  • Look on page 121

9
  • -under ideal conditions
  • -population grows slowly at first
  • -rises to an infinitely large size
  • -J-shaped curve

10
Logistic Growth
  • Logistic growth occurs when a populations growth
    slows or stops following a period of exponential
    growth.
  • Look on page 122
  • S-shaped curve-graph levels off

11
  • Carrying capacity- Usually population fluctuates
    around this point- s-shape

12
Carrying Capacity
  • The number of individuals an area can support
    without ruining the area.

13
Limiting Factors
  • Something that causes population growth to
    decrease
  • Density dependent
  • Density independent

14
Density- Dependent Factors
  • Limit a population when the number of individuals
    reach a certain level
  • Competition for food, water, space, sunlight, etc.

15
  • Predation
  • Parasitism disease

16
Density -Independent Factors
  • Affect all populations regardless of size
  • Weather, natural disasters, seasonal change,
    human interventions (dams,logging, housing
    developments)

17
  • Populations usually decrease dramatically after
    such an event
  • Can be permanent cause extinction

18
Human Population Growth
  • Slow growth historically
  • Now, exponential growth- 6-7 billion

19
  • Some countries have higher growth rates than
    others

20
Demographic Transition
  • Dramatic change in birth and death rates
  • Nutrition, medicine, clean water supplies
    increase survival rates

21
  • Some countries, population stabilizes, but for a
    while, births may exceed deaths

22
  • In some cases, populations may even decrease-
    U.S., Japan, Europe

23
  • Some countries are still growing exponentially
  • Parts of Africa, Mexico, India

24
  • Many young people, of an age where they will
    still be having children

25
  • 9 billion predicted by 2050
  • What will stop/slow the growth?
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