Transcript Population Ecology

Population Ecology
The Study of Populations and the
Factors that Affect Them
Characteristics of
Populations
All population have the following:
• Geographic distribution (range)
• Population Density - the number of
individuals in a certain area
• Rate of Growth
Factors Affecting Population
Growth
population
1) # of Births
2) # of Deaths
3) Immigration and Emmigration
Types of Growth Rates
• Exponential growth
Growth Rate of E Coli
10000
Numbe
r of
bacteria
- occurs when the
reproductive rate of
a population is
constant and NOT
limited by food,
disease, or other
factors
8000
6000
4000
2000
0
Time (hours)
Types of Growth Rates
occurs when the
reproductive rate of
a population levels
off or slows down
Growth Rate of E Coli
10000
Numbe
r of
bacteria
• Logistic growth -
8000
6000
4000
2000
0
Time (hours)
Growth Rate of E Coli
Numbe
r of
bacteria
10000
Carrying
capacity
8000
6000
4000
2000
0
Time (hours)
Carrying Capacity
• Maximum population that an environment can sustain
• Carrying capacity is limited by several factors:
1) Density dependent - have a stronger impact on dense
populations (disease, food availability, predation,
competition)
2) Density independent - impact is the same regardless
of population density (climate change, natural disasters,
human intervention)
What is biodiversity?
• The variety of life in
an area (variety of
species as well as
variety of genetic
information a
species contains)
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Why is biodiversity important?
• Human purposes (ex. Medicine, food,
fuel, industrial chemicals)
• Makes ecosystems more productive
(they produce more total biomass)
• Stabilizes ecosystems by creating more
niches (better resistance to disease and
climate change)
Threats to biodiversity
• Habitat destruction/fragmentation
• Introduction of invasive species
• Habitat degradation (pollution)
Habitat Fragmentation
• When a habitat is
•
divided into smaller
pieces by human
activity
Fragments provide
fewer resources than
whole intact habitats
Change in Species Due to Fragmentation
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Invasive Species
• A species that is not native to its habitat
•
•
(may come from another
continent/country/or region of the same
country)
May damage its new environment and
disrupt the natural food web
Can be costly to control the damage they
cause (billions of dollars!)
Biological magnification
• The accumulation of
•
toxic chemicals going
up the food chain
(concentration of
toxins are magnified)
Higher level
consumers are most
at risk
Red dots = toxic chemical
Global Pollution Problems
• Climate change (global warming)
• Destruction of the ozone layer
• Acid Precipitation
• Biological magnification of toxic
chemicals (on previous slide)
Climate change
• CO2 traps prevents heat from escaping back into
•
•
•
space
More fossil fuel burning = more CO2 in
atmosphere
Deforestation leads to less trees = more CO2 left
in the atmosphere
More CO2 = more heat trapped = WARMER
EARTH!
Greenhouse effect (natural process)
CO2 traps heat
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