Transcript Chapter 19 – Introduction to Ecology

Chapter 18 – Introduction
to Ecology
Section 1: Introduction to Ecology
Ecology

Ecology is the study of the interactions between
organisms and the biotic and abiotic components of their
environment
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Biotic = living
Abiotic = nonliving
Today’s Environment
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The Exploding Human Population
 The world’s human population has
tripled from 2 billion people in 1930
to 6 billion people in 1999
 Causes severe crowding
 Requires an increasing amount of
food, energy and space for
disposing waste
Today’s Environment

The 6th Mass Extinction
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Species are disappearing faster than at any other time since the last mass
extinction
 About 20% of the species of birds have become extinct in the last
2000 years
 Caused by:
 Habitat destruction
 Over-hunting
 New diseases and predators being introduced to non-native areas
Today’s Environment
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The Thinning Ozone Layer
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The ozone layer protects Earth’s living
organisms by absorbing UV radiation
from the sun
Industrial chemicals called
chlorofluorocarbons (CFCs) react
with the ozone and are destroying the
ozone later
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In 1992 a ban was established on using
CFCs and related chemicals
In 1996, the ozone level over
Antarctica was about 50% of the
maximum density
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This allows in extra UV radiation that
can lead to sunburn and skin cancer
Today’s Environment
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Climatic Changes
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Greenhouse Effect: the ability of carbon dioxide and
water vapor to trap the reflected heat from the sun and
direct it back towards the Earth
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Protects the Earth from the deep-freeze of space
Human use of fossil fuels has increased the amount of
carbon dioxide in the atmosphere by 25% in the last 100
years
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The increase of greenhouse gases are trapping excess heat in our
atmosphere, causing global temperatures to rise
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Scientists warn that if the problem is not corrected in the next 10 years,
the condition of our Earth will not be able to be reversed
A Key Theme in Ecology
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No single organism is isolated!!
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The interconnectedness or interdependence of all
organisms is central to the study of ecology
The survival of organisms depends on their interactions with
their surrounding environment
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Ex: Humans cannot live without the plants that produce food and
oxygen
Levels of Organization
The Biosphere
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Biosphere: the broadest and most inclusive level of
organization
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The Earth and its atmosphere make up our biosphere
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Extends from 8 to 10 km (5-6 miles) above the Earth’s surface to the
deepest parts of the ocean
Ecosystems
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The biosphere is comprised of smaller units called
ecosystems
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Includes all of the organisms and the abiotic environment
found in a specific place
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Ex: Pond Ecosystem
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Abiotic components: water temperature, amount of dissolved oxygen and
carbon dioxide, the pH level
Biotic components: insects, fish, algae, aquatic plants, turtles
Chapter 18
Ecosystem
Communities, Populations and Organisms
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A community is all of the interacting organisms
living in an area
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A population includes all of the members of a
species that live in one place at one time
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Ex: All of the fish, turtles, insects, plants and algae make up
the community of a pond
Ex: All of the humans in Vernon Hills
An organism is a single, living thing.

Ecologists study organisms for their adaptations that allow
them to overcome the challenges of their environment
Chapter 18
Community
Brain Break
Try to count the number of black dots on the image below...
There are none!
Chapter 18 – Introduction
to Ecology
Section 2: Ecology of Organisms
Biotic and Abiotic Factors

Environmental factors found in an organisms habitat
are broken into two classes:
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Biotic = living components of the environment
Abiotic = nonliving components of the environment
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Includes:
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Temperature
Humidity
pH
Salinity
Oxygen concentration
Amount of sunlight
Availability of nitrogen
Precipitation
Biotic and Abiotic Factors
Visual
The Changing Environment
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Abiotic factors are NOT constant
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Ex: Temperature
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Varies from hour to hour, day to day, season to season, and year to
year
Varies from place to place:
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Phoenix will be hotter than Chicago
Can vary within a habitat
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Different in temperature between being in the shade of a tree vs. out in
direct sunlight
Responses to a Changing Environment
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Organisms are adapted to function within a specific
range of an abiotic factor
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Ex: Temperature
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All organisms have a range of temperature in which they can
function
To determine the range in which an organism can live, you can
measure how efficiently it performs at specific temperatures
A tolerance curve is a graph of performance vs. values of an
environmental variable
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Performance is usually reduced when the values are outside of the optimal
range
Organisms cannot survive in areas where they are exposed to
conditions that fall outside of their tolerance range
Tolerance Curve
Zones of Physiological Intolerance (no performance)
Swimming Speed
Zones of physiological stress (reduced performance)
Temperature
Acclimation
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Acclimation is the process by which organisms can
adjust their tolerance to abiotic factors
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Ex: Going to the mountains
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If you spend a few weeks in the mountains, your body will acclimate
to the lower oxygen levels by producing more red blood cells in your
body
This will allow your blood to carry more oxygen
Acclimation IS NOT adaptation!!
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Adaptation is a genetic change in a species that occurs over many
generations – acclimation occurs within the lifetime of a species
Control of Internal Conditions
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The abiotic factors within an environment can fluctuate
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Two ways to deal with the changes:
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Conformers: do not regulate internal conditions; they change as
their environment changes
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Ex: Desert lizards’ rises and falls with the temperature of their
environment
Regulators: use energy to control some of their internal conditions
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Ex: humans maintain a constant internal body temperature
Escape from Unsuitable Conditions
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Organisms have developed strategies for surviving
unfavorable environmental conditions:
 Dormancy: a state of reduced activity during which an
organism’s metabolism slows down
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Ex: Reptiles and amphibians “hide” underground and become dormant
during the winter to survive the cold temperatures
Migration: when organisms move to a more favorable
environment
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Ex: Seasonal movements of birds
Resources
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Resources: the energy and materials that an organism
needs to survive
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Ex: Food, water, shelter and sunlight
The resources essential for survival vary between different
species
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Ex: The resources plants require are different from those humans
need
The Niche
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A specie’s niche is the role an organism plays in its
environment
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Includes:
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Range of conditions the organism can tolerate
Methods by which it obtains resources
Interactions with its environment such as reproduction
A fundamental niche is the range of conditions that a
species can potentially tolerate and the range of resources it
can potentially use
A realized niche is the range of resources an organism
actually uses
The Niche
Visual
Niche Differences
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Generalists are species with broad niches
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Can tolerate a range of conditions and use a variety of
resources
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Ex:Virginia opossum  found all over the US and can eat a wide
range of food
Specialists are species that have narrow niches
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Ex: koalas  only feed on leaves from a few species of
eucalyptus trees