Transcript Population Biology Chapter 4 Section 1

“Population
Ecology”
Chapter 4
Section 1
I. Population Dynamics
• A. Population Characteristics:
– 1. Population Density
– 2. Spatial Distribution
– 3. Growth rate
B. Population Density
1. The number of organisms per unit
area.
C. Dispersion
• 1. The pattern of spacing of a population within an
area
• 2. One limiting factor for population dispersion is
availability of food
D. Spatial Distribution
• 1. No population occupies all habitats in the
biosphere
• 2. Example:
– A. Alabama cave fish – found only in Key Cave by
Pickwick Lake (no where else on Earth!)
– B. Dolphins – found in most oceans
II. Population Limiting Factors
A. Keep a population from increasing
indefinitely
-Example: Decreasing food supply
will shrink a population
Fact: Every 3.6 seconds someone dies of
hunger. 75% of them are children.
B. Density-Independent Factors, page 94
(Do not depend of number of members of population!)
• 1.
–
–
• 2.
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–
• 3.
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–
Climate
Temperature
Precipitation
Natural disaster
Storms
Drought
Flooding
Habitat disruption
Fire
Human impact
C. Density-Dependent Factors, page 95
(Any factor that depends on number of
members of a population!)
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1.
2.
3.
4.
5.
Predation
Disease
Parasites
Competition
Food & Water
III. Population Growth Rate
A. Explains how fast a population grows
1. Natality – birth rate
2. Mortality – death rate
B. Know emigration vs. immigration
1. Emigration – moving away from a
population
2. Immigration – moving into a population
C. Exponential growth
• 1. Population growth is slow at first – Lag
• 2. Then, rate of growth increases rapidly due to total
number of members – Exponential
• 3. On a graph this is known as a “J” curve!
Population growth is exponential.
D. Logistic Growth
• 1. Occurs when growth slows or stops following
exponential growth at carrying capacity.
• 2. Increase stops when births are less than deaths
or emigration exceeds immigration
• 3. On a graph this is known as “S” curve
4. Carrying Capacity is the number of organisms
of one species an environment can support.
• 5. If a population is under the carrying
capacity births will exceed deaths
until the carrying capacity is reached.
•
• 6. If a population exceeds the carrying
capacity, deaths will exceed births
until the carrying capacity is reached.
D. R-strategist - Rapid life-history
pattern organisms (page 98)
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•
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1.
2.
3.
4.
5.
6.
7.
Reproduce rapidly.
Produce many offspring.
Have small bodies.
Mature rapidly.
Have short life spans.
Can live in unstable environments.
Biotic and abiotic factors fluctuate.
E. K-strategist - Slow life-history
pattern organisms (page 99)
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•
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1.
2.
3.
4.
5.
6.
7.
Reproduce slowly.
Produce few offspring.
Have large bodies.
Mature slowly.
Have long life spans.
Need stable environments.
Carrying-capacity changes little.
4,767 years
4,767 years,
F. Human Population Growth
(4.2, page 104)
• 1. Zero population growth: birthrate = deathrate
• 2. Age structure: the number of male and females in
each age group (pre-reproductive, reproductive, and
post-reproductive)
Biodiversity
Chapter Five Section One
IV. What is biodiversity?
• A. Variety of life!!!
• B. Importance to nature
– 1. Complex relationships exist among
organisms
– 2. The loss of a species (extinction) affects
many other species
• Remember food webs!!!!!
3. Life Depends on life!!!!!
C. Biodiversity = Stability
D. Three Types of Biodiversity:
1. Genetics
2. Species
3. Ecosystem
1. Genetic Diversity – variety of
inherited genes
2. Species Diversity – number of
different species
3. Ecosystem Diveristy: Variety
of ecosystems in the Biosphere
E. Importance to People
• 1. We are living and we depend on other
living things.
• 2. Food Sources
3. Medicines
**25% are plant derived**
V. Loss of Biodiversity
• A. Extinction
1. Background (gradual)
2. Mass (short)
Miss Waldron's Red Colobus (Monkey)
B. Save the Polar Bears
~The Eagle is a success story!
C. Endangered Species
Endangered Species Act of 1973
• Protects Endangered and Threatened
Species.
• WHAT LEADS TO THE BIGGEST
LOSS OF BIODIVERSITY????
VI. Threats to Biodiversity
• A. Habitat Loss
• (Biggest threat to biodiversity.)
B. Habitat Fragmentation –
separation of ecosystem
C. Habitat Degradation
1. Acid Precipitation
2. Ozone Depletion
• Caused by CFCs.
D. Water Pollution
E. Land Pollution
Example:
DDT almost caused the extinction of
the Bald Eagle in the continental US!
DDT (dichlorodiphenyltrichloroethane) is
an organochlorine insecticide which is a
white, crystalline solid, tasteless, and
almost odorless.
F. Overexploitation
Hunted for their Tusks
G. Introduction of Exotic Species
What is an Exotic Species?
Water Hyacinth
A species of organism that is not native to an area.
Examples of Exotic Species
Zebra Mussels
Sea Lamprey on Trout
Kudzu
Feral pig
How did they get here?
• Intentionally
• Favorite plants brought from the
homeland to a new country.
• Pig brought and released for food.
• Accidentally
• Fungus brought with plants from other
counties.
• Norway rats brought as stowaways on
ships.
Ox-eyed Daisy
Are all Exotic Species Harmful?
Not all exotic species should be
considered harmful.
Wheat and oats form the basis of the
agricultural industry and supply a
large proportion of the diet of the US.
What are the Results of the
Introduction of Harmful Invasive
Species?
Invasive species are responsible for
significant ecosystem destruction all
over the world.
Purple Loosestrife
Negative Impact
According to a government report, "Invasive
Plants are Changing the Landscape of America,"
Introduced species now
comprise between 8 to 47
% of the total flora of most
states.
What is being done?
A Unified Defense Against Invasive Species
On February 3, 1999, Executive Order 13112 was
signed establishing the National Invasive Species
Council
Dandelion