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.