Chapter 5 Characteristics of Populations 5-1

1
Chapter 5 Characteristics of Populations 5-1

• Geographic Distribution range, area inhabited
  by a population
• Density of individuals per unit of area
• Growth Rate Increase, Decrease, or Stay the
  Same

2
Population Growth

• 3 Factors that affect population growth
• of births (birth rate)
• of deaths (death rate)
• entering and leaving
• Immigration movement of individuals into an
  area (growth)
• Emigration movement of individuals out of an
  area (decrease)

3
Exponential Growth

• Exponential Growth individuals reproduce at a
  constant rate
• Ideal conditions with unlimited resources are
  necessary for exponential growth.
• Ex One bacteria cell reproduces every 20
  minutes.
• How many after 20 min.?
• How many after another 20 min?
• How many after another 20 min?
• How many after one day?

4
Logistic Growth

• Logistic Growth when population growth slows or
  stops (due to decreased availability of
  resources)
• Carrying Capacity The largest number of
  individuals that an environment can support

5
5-2 Limits to Growth

• Limiting Factor Causes population growth to
  decrease
• Competition
• Predation
• Parasitism/Disease
• Extreme Climates
• Human Disturbances

6
Density Dependent Factors

• Density Dependent Limiting Factors depends on
  population size and density
• Factors act most strongly when population is
  large and dense
• Ex Competition
• Ex Predation
• Ex Parasitism

7
Density-Independent Factors

• Density Independent Limiting Factors affect
  all populations, regardless of size
• EX weather, natural disaster, seasons, and
  humans

8
6-3 Biodiversity

• Biodiversity sum total of genetically based
  variety of all organisms
• Human threats to biodiversity
• Altering habitats
• Hunting to extinction
• Pollution
• Introducing foreign species to new environments

9
Invasive Species
Pythons in Florida
Invasive Species Disaster
10
Conserving Biodiversity

• Conservation wise management of natural
  resources (preservation of habitats and wildlife)
• Ecological Hotspot where habitats/species are
  in immediate danger of extinction

11
Why is biodiversity important?

• The greater the VARIATION in an ecosystem, the
  more likely it is to RECOVER if there is a
  disruption.
• Increased diversity healthier environment.
• Biodiversity is a resource
• Most pharmaceutical drugs from plants.
• Future food sources, building materials, etc
• Beauty, fascination, wonder
• Recreation (ecotourism).

12

• Threatened
• Abundant in range, but decreasing in numbers.
• At risk
• Endangered
• Very few remaining in natural range
• At risk for going extinct
• Extinct
• Local extinction gone from local range
• Ecological extinction gone from natural range
  (in zoos only)
• Biological extinction gone from Earth forever.

13
HIPPCO Factors Leading to Species Extinction

• Habitat Loss
• Hot spots with greatest impact tropical areas,
  coral reefs, wetlands, grasslands, water (fresh
  salt)
• Invasive Species
• Organisms not normally in habitat
• Pollution
• Air, water, soil impacts
• Population
• Arrival of humans and exponential population
  growth
• Climate Change
• Overexploitation
• Ocean Fisheries