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Environment

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Title: Environment


1
Environment Population
  • Chapter 5 6

2
Affects on Population Size
  • Biotic Factors Living elements in an ecosystem.
    These can effect population size!!
  • EX Predator Prey relationships, the amount of
    available producers to start of food webs, etc,
    competition among organisms for food, etc
  • Abiotic Factors The NONLIVING elements in an
    ecosystem. Affect HOW organisms live
  • EX Temperature, amounts of rainfall, type of
    soil, elevation, etc.

3
Predator/Prey Relationships When prey
decline, predatory s decline as well
4
How to Reduce Competition for Resources
  • Competitive Exclusion Principal States that no 2
    species can occupy the same niche in the same
    habitat at the same time.
  • EX Different species of Warblers (birds) occupy
    different parts of treee in order to reduce
    competition for food shelter
  • Niche Full range of physical biological
    conditions in which an organism lives and the way
    in which the organisms useses those conditions

5
3 Factors that affect population size
  • Number of Births Birthrate
  • Number of Deaths Deathrate
  • Number of individuals that enter Immigration
  • Number of individuals that leave Emigration

6
Exponential Growth
  • A pattern of growth represented by a J-shaped
    curve.
  • Individuals reproduce at a constant rate.
  • Will not continue in a natural population for
    very long because resources eventually run out.
  • Example Oil boom towns.
  • Look at page 121

7
Exponential Growth
8
Logistic Growth
  • Population or growth slows or stops following a
    period of exponential growth.
  • Represented by an S-shaped curve.
  • Look at page 122

9
Logistic Growth
10
Carrying Capacity
  • It is the population size when the growth rate
    stops.
  • Defined as the number of individuals of a
    particular species that a given environment can
    support.

11
Limiting Factors cause populations to decrease
  • Density Dependent (BIOTIC FACTORS)
  • Depend on population size.
  • Include competition, predation, parasitism
    disease
  • Example in a predator/ prey situation, if the
    prey
  • decreases, then the predator population will
    soon decrease too.
  • Density Independent (ABIOTIC FACTORS)
  • Do not depend on population size.
  • Include unusual weather, natural disasters,
    seasonal cycles, human activity such as damming
    rivers.

12
Destruction of a Species
  • Humans have become the most important source
    of environmental change.
  • Hunting
  • Gathering
  • Agriculture
  • Industry
  • Urban development

13
Destruction of a Species
  • Humans reduce biodiversity by destroying
    habitats.
  • Hunting species to extinction.
  • Introducing toxic compounds into food webs.
  • Introducing foreign species into new
    environments.
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