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Ecology: Part 2
Chapters 4 & 5
Principles of Population
Growth
 A population is a group of organisms, all of the
same species, that live in a specific area.
 A healthy population will grow and die at a
steady rate unless it runs out of food or space,
or is attacked in some way by disease or
predators.
What can limit growth?
 Limiting factors, such as availability of food,
disease, predators, or lack of space, will cause
population growth to slow
Carrying capacity
 The number of
organisms of one
species that an
environment can support
indefinitely
 When a population
overshoots the carrying
capacity, then limiting
factors may come into
effect.
 Deaths begin to exceed
births and the population
falls below carrying
capacity
Carrying capacity
Density factors and
population growth
 How organisms are dispersed can be important.
 two kinds of limiting factors that are related to
dispersal: density-dependent and density-independent
factors.
 Density-dependent factors include disease,
competition, predators, parasites, and food.
 Density-independent factors can affect all populations,
regardless of their density.
 Most density-independent factors are abiotic factors, such as
temperature, storms, floods, drought, and major habitat
disruption.
Organism Interactions
Limit Population Size
 1.Predation affects
population size
 Populations of predators
and their prey are known to
experience cycles or
changes in their numbers
over periods of time
Lynx
Hare
Organism Interactions
Limit Population Size II
 2. Competition within a population
 When only a few individuals compete for
resources, no problem arises.
 When a population increases to the point at
which demand for resources exceeds the
supply, the population size decreases.
Organism Interactions
Limit Population Size III
The effects of crowding and stress
 These include aggression, decrease in
parental care, decreased fertility, and
decreased resistance to disease
 become limiting factors for growth and keep
populations below carrying capacity.
Biological Diversity
 Biodiversity refers to
the variety of species
in a specific area.
 The simplest and
most common
measure of
biodiversity is the
number of different
species that live in a
certain area.
 Areas around the
world differ in
biodiversity
Where is biodiversity found?
 Biodiversity increases as
you move toward the
equator.
 Tropical regions contain
two-thirds of all land
species on Earth.
Importance to nature
 Living things are interdependent
 Living things can be niches for other living
things.
 Populations are adapted to live together in
communities.
 Scientists do know that if a species is lost from
an ecosystem, the loss may have
consequences for other living things in the
area.
 Loss of biodiversity causes instability in
ecosystems
Importance to people
 Biodiversity provides
humans with food,
clothing, shelter, oxygen,
soil fertility, etc.
 Loss of biodiversity causes
instability in ecosystems
 Biodiversity could help
breeders produce additional
food crops. Food supplies are
shrinking
 can be used to improve
people’s health- some of
which may provide future
drugs. Ex: rosy periwinkle, used
in anti-cancer medication.

Penicillium
Loss of Biodiversity
 Extinction is the disappearance
of a species when the last of its
members dies.
 Extinction is a natural process
and Earth has experienced
several mass extinctions during
its history.
 However, the current rate of
extinction is very high

Example: 1/8 of all plant species are
endangered, and some estimates put
140,000 species extinct per year
 Overexploitation of wildlife also
threatens many species
Loss of Biodiversity II
Overexploitation of wildlife
also threatens many species
 A species is considered
to be an endangered
species when its
numbers become so low
that extinction is
possible.
 When the population of a
species is likely to
become endangered, it
is said to be a
threatened species.
Over-Exploitation
•Over-exploitation is the excessive hunting or fishing of specific species that
causes their populations to drastically decline.
Over-exploitation of species causes the loss of
genetic diversity and the loss in the relative
species abundance in an ecosystem.
Threats to Biodiversity
1. Habitat loss
The loss of tropical rain forests
and marine habitats are
especially devastating
2. Habitat fragmentation
the separation of wilderness
areas from other wilderness
areas
DEFORESTATION
WHATS GOING ON?
Deforestation:
-Changes a forest into an area used for grazing
land, logging, or urban purposes
-Reduces biodiversity
-Occurs even here in Buffalo when a new model
home or shopping center is built
- Or can occur naturally
Impacts of Deforestation:
 Can degrade carbon
storage
 Throws off the
regulation of
water balance and river
flow
 Can cause regional
climate patterns
to
change drastically over
time
 increase effect of
infectious diseases
How to save
:rainforests and stop the deforestation
 Addressing
deforestation
 Restoring and
rehabilitating
ecosystems
 Funding rainforest
conservation efforts
 Expand protected
areas
Introduced species ~
invasive
 People sometimes
introduce a new species
into an ecosystem, either
intentionally or
unintentionally.
 These species can
cause problems for the
native species
 these species can grow
at an exponential rate
due to the fact that they
are not immediately as
vulnerable to local
competitors or predators
as are the established
native species.
Introduced species
 Non-native species
 transplanted populations grow
exponentially in new area
 out-compete native species
 loss of natural controls
 lack of predators, parasites,
competitors
 reduce diversity
 examples




African honeybee
gypsy moth
zebra mussel
purple loosestrife
gypsy moth
kudzu
Purple loosestrife
1968
1978


reduces diversity
loss of food & nesting sites
for animals
Zebra
mussel
~2 months


ecological & economic damage

reduces diversity
loss of food & nesting sites
for animals
economic damage
Threats to Biodiversity
II
3. Habitat degradation:
the damage to a habitat by pollution.
 Three types of pollution are air, water, and land
pollution.
Air pollution
 Pollutants enter the
atmosphere in many
ways—including volcanic
eruptions and forest
fires.
Air pollution II
Rapid global warming could alter the
entire biosphere
 Burning fossil fuels is
increasing the amount of CO2
and other greenhouse gases
in the air which increase
global temperature
negative effects:
 Change in climate
patterns
 Melting of polar ice
 Flooding of coastal
regions
 Increase in the rate of
species loss
Wide
World Wide
LocallyNew
Locally – New York
York
Air pollution III
 Acid precipitation—has been linked to
the deterioration of some forests and 
lakes.

power plants
industry
transportation
nitrogen oxides
sulfur dioxide
Acid rain
Acid Precipitation
 What Causes Acid Rain?


Natural Causes: Volcanoes and
decaying vegetation.
Human Causes: Factories and
other productions using fossil fuels.
What is in Acid Rain?



Acid Rain consist of gasses such as
sulfur dioxide(SO2) and nitrogen
oxide (NO).
These gasses react in atmosphere
with water, oxygen and other
chemicals to form various acidic
compounds.
These compounds can travel
sometimes hundred of miles from
prevailing winds.
 Plants:
 Roots become damaged from the acidic rainfall.
 Acid rain can cause the growth of the plant to be killed or stunted.
 Nutrients in the soil can be destroyed, limiting the resources for
the plants to take in.
 Waxy Layer-Cuticle can be reduced, allowing the plant to dry out
and be susceptible to disease.
 Animals:
 Acid Rain and other populations can hurt a food web.
 All organisms are interdependent on each other for energy.
 If one organism is effected, everything above is effected.
1.
Reducing Acidic Lakes & other bodies of Water

Adding large quantities of alkaline substances.
Clean Coal Technology: promises to dramatically reduce the
contaminants and pollutes that are problematic for burning coal.
Over time as power plants switch to clean coal tech. we can help
reduce pollution and reduce our dependence on foreign oil.
2.
In your home:

Only run dishwasher/washing machine with full load.

Turn off lights in empty rooms or when you will be away from
home.

Turn down heat at night and when will not be at home at night.

Don’t use your air condition often.
3.
In the Yard:

Keep pool covered when your not using it.
Air pollution IV
 Destruction of the
ozone layer has
increased the
ultraviolet radiation
reaching Earth’s
surface.
 probably results from the
accumulation of
chlorofluorocarbons chemicals used in
refrigeration and aerosol
cans, and in certain
manufacturing processes.
Ozone Depletion
protects from
UV rays
Loss of ozone above Antarctica
Effects of loss of Ozone
Wrinkles & SKIN CANCER
Water pollution

Excess fertilizers and animal
wastes are often carried by
rain into streams and lakes.

The sudden availability of
nutrients causes algal blooms,
the excessive growth of algae.
->

Detergents, heavy metals, and
industrial chemicals in runoff
can cause death in aquatic
organisms.

Oil spills ->

Abandoned drift nets in
oceans have been known to
entangle and kill dolphins,
whales, and other sea life.
Actions that need to be taken:




Remove the pollutants before the water returns to the environment.
Collect the water by a system of underground pipes-- sewers-- which carry it
to one or more central treatment facilities.
Most of these are located near bodies of water into which the treated
wastewater is discharged.
Smaller sized farms tend conserve water and apply and fertilizer to fields
more responsibly, minimizing their impact on local water systems, rather
than large industrial farms which do not pay close attention to their water
supplies and use of fertilizer.
•This picture
shows a water
pollution
treatment facility
Land pollution
 Trash, or solid waste
 The use of pesticides and
other chemicals
 Chemical pesticides are
concentrated in food
chains by biological
magnification
What is Biomagnification?
 Biomagnification is the
increase in the concentration
of a substance
 Occurs throughout a food
chain, not an organism
 Chemical must be
 Long-lived
 Mobile
 Soluble in fats
 Biologically active
Impact
 Some of the increasing levels
include mercury and DDT,
chemicals that harm organisms
 Organisms higher on the food
chain absorb more toxins since
they eat more
 Examples: bald eagle, polar
bear
 Humans who eat meat can
also be affected by the
chemicals
Solving the Problem
 Unfortunately, scientists don’t know all of
the chemicals that cause
biomagnification
 Chemicals discovered to be harmful are
taken off the market, but it might be too
late
 The only way to eliminate the chemical
completely from a food chain is to ban
the product and wait.
5.2: Conservation of
Biodiversity
• Section Objective
•
Describe strategies used in conservation
biology.
• Conservation biology is the study and
implementation of methods to protect
biodiversity.
• Natural resources are those parts of the
environment that are useful or necessary for living
organisms.~ include sunlight, water, air, and plant and
animal resources.
Conservation Biology
Legal protections of
species
• the U.S. Endangered
Species
Act
became law in 1973.
Preserving habitats
the creation of
natural preserves
and parks.
Conservation Biology
 Working with people
• The philosophy of
sustainable use strives
to enable people to use
natural resources
in ways that will benefit
them and
maintain the ecosystem.
 Reintroduction and
species preservation
programs
Conservation Biology
 Bioremediation is the
use of living
organisms to detoxify
polluted ecosystems
–These lichens are
concentrating mining
wastes
Reliance upon modern varieties
of rice has caused more than
1,500 local rice varieties in
Indonesia to become extinct
Humans now rely upon just
14 species of mammals and
birds to supply 90% of all
animal-derived foods
What Can You Do?
Keep pets indoors
Choose tap over bottled water
Adjust two degrees
-To help out locally and
globally you can also
volunteer or donate to the
American Museum of Natural
History’s Center for
Biodiversity and Conservation
Choose green energy
What Can You Do?
 Bring your own
reusable canvas grocery
bags when grocery
shopping.
 Drive less. Take
bikes, walk or carpool
whenever possible.
Plant
a tree.
 Don't let heat
escape from your
house over a long
period.
 Buy recycled paper
products and recycle as
much of your waste as
possible.
 Replace a regular incandescent
light bulb with a compact
fluorescent light bulb.