Agenda
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Warm-up
Population Growth demo
Notes
Population Growth worksheet
Population Activity
• What is an infection?
• Bacteria that invades your body
and can also move from person to
person
Population Dynamics
Principles of Population
Growth
• Population
– A group of organisms, all of the
same species, that live in a specific
area at the same time.
• Population growth is defined as
an increase in size of a population
over time…
• However, populations grow
at different rates.
Linear Growth
• If a population grew at a set
amount each year, say by 10
organisms per year, then the
population has LINEAR GROWTH
• However, populations normally do
not have linear growth. Linear
growth looks like this
(Please draw in your notes)
Question
•
Your parents give you two options for
allowance
1. 1,000 a month
2. A penny on the first day of the month
that doubles to two pennies on the
second day
and so on until the last day
of the month
• Which option do you choose?
.01
.64
81.92
10,485.76
1.28
163.84
209711.52
.02
2.56
327.68
41943.04
.04
5.12
.08
10.24
655.36 1310.72
83886.08
5368709.12
2684354.56
20.48
2621.44
167772.16 335544.32
10,737,418.24
1342177.28
.16
Over 10
million!!
.32
40.96
5242.88
671088.64
Exponential Growth
• If you graph the allowance we just
saw on the graph it will look like
this: (Please draw in your notes)
16000
14000
12000
10000
8000
6000
4000
2000
0
1
2
3
4
5
6
7
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10
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Exponential Growth
• A population that is growing without any
limits, would have exponential
growth.
• Meaning that as the population gets
bigger, it also will grow faster
• But, populations cannot keep
exponential growth for very long,
because the environment would
not be able to support it.
Exponential Growth
Carrying Capacity
• The environment has a
CARRYING CAPACITY for each
population…
• Carrying capacity is the number
of organisms that an environment
can support.
• Once a population reaches its
capacity, its growth stops.
Question
• What are some examples of things
that can limit growth?
What can limit growth?
• Limiting factors limit growth
• Different sizes of populations
will also have different factors
affecting them.
• When growth has been limited
its graph will look like this:
1400
1200
1000
800
600
400
200
0
1
2
3
4
5
6
7
8
9
10
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Density Dependent Factors
• Density Dependant Factors are
factors that have an increasing effect as
the population increase, hence will
affect larger populations.
Examples: Disease, Competition,
Parasites, Predators, Food
• These types of factors spread more
quickly in larger populations.
Density Independent Factors
• Density Independent Factors
effect any population, regardless
of size. Population size does not
matter.
• Examples: Volcanic eruption,
Temperature, Storms, Floods,
drought, chemical pesticides
Organism Interactions Limit
Population Size
• Predation
– Predator consuming prey on a large enough
scale can have a drastic effect on the size of
prey population and hence predator population
• Competition
– Many individuals competing for scarce supplies
– Density-dependent factor
• Crowding and Stress
– Also density dependant. Stress symptoms
include aggression, decrease in parental care,
decreased fertility, and decreased resistance to
disease
Predation
Question
• Do any populations exhibit
exponential growth?
Human Population
Human Population Growth
World Population
• Census - Taken in the US once
every 10 years
• Demography - Study of human
population size
– 6 Billion in 1999
– 1.3 Million per year in 2002
Warm-Up
Which of the following might be
a limiting
factor in an organism’s survival?
A. Abundance of predators
B. Temperature and light
C. Food availability
D. All of the above
Biodiversity loss
• http://www.youtube.com/watch?v
=TP-V4VLLHNE
Human Population Growth
• Human Population Growth is
Different that other organisms
because humans consciously
change their environment
– Eradication of diseases
– Methods for producing more food
– Technology
Calculating Growth Rate
• Birthrate - Number of live births
per 1000 population in a given
year
• Death rate - Number of deaths
per 1000 population in a given
year
Immigration vs Emigration
• Immigration is the movement into
a country.
• Emigration is the movement out of
a country.
•
(Birth Rate + Immigration Rate) – (Death Rate + Emigration Rate)
= Population Growth Rate (PGR)
Age Structures
• Age Structures tell us how many
people are in each age group…
• A younger aged population will
grow more rapidly than an
older population.
• Which age
structure
diagram
has more
young
people?
• Why might
that be?
A
B
C
Biodiversity
• http://www.youtube.com/watch?v=HA3xN
MJnFuo
Biological Diversity and
Conservation
Biological Diversity
•Biodiversity - Variety of
species in a specific area
Importance of Biodiversity
• Interdependence of organisms
– Life depends on life
• Stability
– Many species and diversity allows for better chances of
survival
• Important to people
– Foods
– Industrial products
– Medicines such as painkillers, antibiotics, heart
medication, anti-depressants, anti-cancer drugs
– Depend on other organisms for oxygen, nutrients
– Clothes, Furniture, Beauty…
• Can you think of any other reasons why
biodiversity is important?
Loss of Biodiversity
• Extinction Disappearance of a
species when the last of
its members die
– Passenger Pigeon (1914)
• Endangered Species Numbers become so low
that extinction is possible
– Humpback Whale
• Threatened Species Populations decline rapidly
and are likely to become
endangered
– Grizzly Bear
http://ecos.fws.gov/tess_public/StartTESS.do
Threats to Biodiversity
1. Habitat Loss
– The largest threat
– 70’s – 80’s Amazonian rainforest
– Coral reefs
Threats to Biodiversity
2. Habitat Fragmentation
–
Separation of wilderness areas from other
wilderness areas
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Increased extinction of local species
___________ of ecological processes
New opportunities for invasions by introduced or
exotic species
Increased risk of fire
Changes in local climate
Smaller fragments mean less biodiversity
Geographic isolation leads to genetic
isolation
Some organisms need large areas – for
hunting and reproduction
Biotic Effects of Fragmentation
• Animals that require large areas in
which to graze can no longer do so –
animals starve
• Likewise large predators can not obtain
enough to eat in a small spot - animals
starve
• Migration becomes difficult and species
either starve or get wiped out after
events such as fire
Abiotic Effects of
Fragmentation
• Climate can change in the areas
• Think about the temperature in a forest
vs. open spaces…
• Edge Effect – The different conditions
along the boundaries of an ecosystem.
as areas become smaller the changes at
the edges start to influence the
conditions inside.
Threats to Biodiversity
3. Habitat degradation - Damage
to a habitat by pollution
• Types: Air, Water, and Land
I. Air Pollution
• Importance: can have negative effects on
organisms, such as breathing problems,
genetic mutations, as well as irritating the
eyes & nose.
• Causes: Volcanic eruptions, forest fires,
Chlorofluorocarbons (CFCs),
• burning fossil fuels is the #1 cause
Problems from Air Pollution
• Acid Precipitation - Caused by
emissions from burning fossil fuels.
These emissions combine with water
vapor in the air to form rain, snow,
sleet and fog with low pH values
– Leeches nutrients from the soil, kills plants,
lowers pH of water supplies, Responsible for
killing many trees in US forests
– Also strongly effects lake ecosystems killing
plants, animals & other organisms
Air Pollution Continued
• Ozone layer depletion - Ozone =
O3, It absorbs some of ultraviolet
waves striking atmosphere –
natural sunscreen
• CFCs break down ozone
– CFCs used in refridgerators, air conditioners,
some aerosols and used to make polystyrene
• Spring – hole at largest
• Hole allows more UV rays in which
causes increased exposure to UV
radiation, this can lead to mutations.
II. Water Pollution
• Importance: degrades aquatic
habitats in streams, rivers, lakes and
oceans thereby strongly affecting and
even killing aquatic life.
• Causes:
1. Excess fertilizers, animal wastes
from farms can be carried into the
water. These nutrients cause algal
blooms which can further harm
aquatic life by removing needed
oxygen from the water. Additionally,
silt from eroded soils can clog gills of
fish
2.Detergents, heavy metals, chemicals
3. Abandoned drift nets – kills ocean
life
Water Pollution
III. Land Pollution
– The average American produces
about 1.8 kg of solid waste daily
• Most trash becomes part of landfills
• Possible contamination of ground water
supplies
– Pesticides
• DDT passed through food chains
IV. Exotic / Introduced
Species
• Exotic/Introduced Species Species that are not native to a
particular area
• People sometimes introduce a new
species into an ecosystem
• Can cause problems for native
species
Figure 52.5, 2
Introduced species
When species that are not native are introduced to an area, a number of different problems can occur.
Competition: In North
American marshes, purple
loosestrife is crowding out
native organisms.
Disease: An introduced
fungus has virtually
wiped out the American
chestnut.
Predation: The brown tree
snake has extinguished
dozens of bird species on
the island of Guam.
Conservation of Biodiversity
Are you part of the solution or
part of the problem?
Conservation Biology
•
Conservation Biology - Study and
implementation of methods to protect
biodiversity
1. Natural resources - Parts of the
environment that are useful or necessary
for living organisms
2. Legal protection of species
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–
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US Endangered Species Act 1973
http://endangered.fws.gov/esa.html
Illegal to harm endangered or threatened
species
Conservation Biology
3. Preserving habitats
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Natural Preserves
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•
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Yellowstone National Park
Big Cypress National Preserve
Crater Lake National Park
4. Habitat Corridors
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Protected strips of land that allow the
migration of organisms from one
wilderness area to another
Allows populations to be connected to
each other
Why is this important?
Conservation Biology
5. Working with people
– Rangers
– Sustainable use - Enable people to
use natural resources in way that
will benefit them and maintain the
ecosystem
Conservation Biology
Reintroduction and Species
Preservation Programs - Release
organisms into an area where the
species once lived
Conservation
Biology
• Captivity
– Organism that is held by people
• Protecting Plant Species
– Protect environment
– Cool seeds and store for long periods
of time in a seed bank
50 ways to save the planet
• Ask yourself… “Are you part of the
problem, or part of the solution”.
• Please find at least 50 ways you
can help save the planet 
• Note: Instead of a poster on the
50 ways you may instead pick one
way to help save the planet and do
a video PSA.