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Chapter 3: The Biosphere
What is ecology?
Ecology
• Ecology –study of interactions
among organisms,
between organisms, and their environment
• Interdependence –
Life depends on other living things and natural
resources (air, water, land)
Levels of Organization
1. Species
Individual
living thing
Levels of Organization
2. Population
• Groups of individuals
of same species in an area.
Levels of Organization
3. Community
• Different populations
that live together in an area.
• Several populations interacting together.
Levels of Organization
4. Ecosystem
• Collection of all
organisms
(biotic)
in a particular
place together with
the abiotic
(physical)
environment.
Levels of Organization
5. Biomes
• Groups of ecosystems
with similar climate and communities.
Levels of Organization
6. Biosphere
• The highest
level of
organization.
• The portion of
the Earth
that supports
life.
BIOSPHERE
BIOME
ECOSYSTEM
COMMUNITY
POPULATION
SPECIES
Levels of Organization
BIOSPHERE
BIOME
ECOSYSTEM
POPULATION
SPECIES
COMMUNITY
Biotic and Abiotic Factors
• Biotic – living
– Plants, Animals ,Mold, Fungi,
Bacteria, Protist
• Abiotic – Nonliving
– Sunlight, soil, wind, water,
temperature
Ecological Methods
1. Observation –
1st step to designing an
experiment
2. Experiment –
test hypotheses
3. Modeling –
make models based on
observation & experiment
• Helps make future predictions
3.1 Review
1. Many populations together is called a…
Community
2. Combination of biotic and abiotic factors in an
environment make up the…
Ecosystem
3. What’s the different between biotic and abiotic?
Biotic – living factor
Abiotic – nonliving factor
3.1 Review Picture
• Pick any animal you want and draw a picture
similar to the one below. Include “species,
population, community, and ecosystem”
3.2 ENERGY FLOW
(Autotrophs and Heterotrophs)
• One of the most important factors
to determine capacity to sustain life is
Energy Flow
Autotrophs (producers)
• Trap light energy to produce food
– Plants
– Some protists
– Some bacteria
• Photosynthesis –
Converts light into chemical energy
6CO2 + 6H2O SUN
C6H12O6 + 6O2
• Chemosynthesis –
Converts chemical energy into carbohydrates
Heterotrophs (consumers)
• Must acquire energy from
consuming other organisms
–
–
–
–
Herbivores – plants
Carnivores – animals
Omnivores – both
Detritivores –
eat dead plants & animals
– Decomposers – break down
organic matter
3.2 Review
1. Another name for autotroph is…
Producer
2. What are the two processes autotrophs use to
make energy?
Photosynthesis and Chemosynthesis
3. What are the four types of –vores?
Carnivore, herbivore, omnivore, detritivore
3.3 Energy Flow in
Ecosystems
• Food Chains and Food Webs
Food Chains and Food Webs
SUN
Autotrophs
Heterotroph
1. Food Chain – shows simple energy transfer
2. Food Web – shows possibilities
of energy transfer
Trophic Levels
• Trophic Levels – each step in a food chain/web
T Level 4?
T Level 2
T Level 1
T Level 3
Ecological Pyramids
• Ecological Pyramids – shows relative amount of
energy at each level (10% rule)
• Biomass – total amount of living tissue
within a trophic level
3.3 Review
1. Which is more complex – food chain or web?
Food web
2. Grass  rabbit  fox  alligator – Which is T2?
Rabbit
3. What is biomass?
Amount of living tissue in each trophic level
4.2 Niches and Community
Interactions
Tolerance
Species ability to survive and reproduce under a
range of environmental circumstances.
Intolerance Zone
Habitat
• General place an organism lives.
• Determined by species tolerance.
Niche
Range of physical and biological
conditions in which a species lives and
the ways the species obtains what it
needs to survive and reproduce.
Niches
• Resources – Things needed for life
– Plants- sunlight, water and soil nutrients
– Animals- nesting, space, shelter, food, places to feed
• Physical resources– Abiotic factors
required for survival.
– Ex- amphibians lose and absorb water through skin::must
live in moist places.
• Biological resources– Biotic factors
required for survival.
– E.g. when/how reproduces, food, way obtains food.
Competition
• Different organisms attempting to use
essential resources.
• Same resources at same time and place =
competition
– Intraspecific competition-same species competing
– Interspecific competition- different
species competing
What do you think these two
males are fighting over?
Competitive Exclusion Principle
-No two species can occupy exactly
the same niche at the same time.
-One species will win
and survive.
-One will lose and die.
Dividing Resources
• Helps determine the
number
and kinds
of species in a
community and the
niche each species
occupies.
Review so far… (14 points)
• Pick an animal. Any animal.
• On a blank piece paper draw or write a paragraph
using COMPLETE SENTENCES:
– It’s habitat
– Some things that would give it optimal tolerance.
– Some things that would cause the habitat to be
intolerable.
– It’s niche (list two physical and two biological factors
it interacts with)
– When might it come into competition?
– What could it do to divide resources with competition?
Predation, Herbivory, and Keystone
Species
Predation
Where one animal (the predator)
captures and feeds on
another animal (the prey)
Predation
• Predators affect size of prey population
and determine the places prey can live.
– E.g. birds can play important role in regulating
mouse population sizes
Herbivores
• Herbivory - Animal (herbivore) feeds on
producers (plants)
• Affect size and distribution
of plants.
• E.g- Many white-tailed
deer are eliminating
their favorite
food plants across US.
Keystone Species
• A single species that can
dramatically change
in a community
• Ex- Sea otters eat large amounts of sea urchins,
which eat kelp.
• Sea otters almost eliminated by hunting; urchins
population increased; ate all the kelp.
• Other organisms also disappeared.
Symbioses
Any relationship in which
two species live
closely together
• Three main classes:
1. Mutualism
2. Parasitism
3. Commensalism
Mutualism
• Relationship in which both species benefit
• E.g. – Sea anemone and clownfish
• Sea anemone-offers shelter; clownfish protects for
preditors.
Parasitism
Relationship where one
organism lives
inside or on
another organisms and
harms it.
Commensalism
Relationship where one
organism benefits
and the other is
neither
harmed or helped
4.2 Review
1. What could be a physical and biological resource
for a flower?
Phys – Sun
Bio – Roots, insects, etc.
2. When does competition occur?
Need for same resources at same time
3. Ants protecting a tree that gives the ants shelter
is an example of…
Mutualism
Symbiosis Review
• A : Find an example of each type of symbiosis and
explain why it is that type.
• B: Draw a picture of one type of symbiosis.
Chapter 5
Populations
5-1
How Populations Grow
How Populations Grow
• Characteristics of Populations
• 4 important characteristics of a
population
–Geographic distribution
–Density
–Growth rate
–Age structure
Geographic Distribution
–Geographic distribution –
Area inhabited
by a population.
–Ranges can vary enormously
in size
Population Density
• Population Density - number of
individuals per unit area.
• This picture shows the population density
of people.
Populations Growth
• Three factors affect population size:
– number of births
– number of deaths
– number of individuals that
enter or leave
the population.
* Simply put, a population will increase or decrease in size
depending on how many individuals are added to it or
removed from it
Immigration & Emigration
• Immigration
–movement of individuals
into an area
• causes growth.
• Emigration
–movement of individuals
out of an area
• causes decrease.
Age Structure
• Number of males and females of
each age a population contains.
• Age structure greatly effects reproduction
Exponential Growth
• Exponential growth – When the
offspring generation is larger
than the generation before.
• Population size will increase if there is
abundant space and food, and
protected from predators and disease
• Under ideal conditions with unlimited
resources.
Logistic Growth
• Logistic growth- occurs when growth
slows or stops following
a period of exponential growth.
• As resources decrease,
the growth of a population slows or stops.
• The general, S-shaped curve of this growth
pattern, is called logistic growth.
Carrying Capacity
Maximum number of
individuals of a particular species that a
given environment can support.
1. List the four characteristics of population.
Geographic distribution, population density,
growth rate, age structure
2. What factors can change a population's size?
Birthrate, death rate, immigration and emigration
3. What is carrying capacity?
Max number of a population an
environment can support
5.2 Limits to
Growth
• Limiting factor – factor that controls
the growth of a population.
– Density dependent
– Density independent
• Limiting factors determine the
carrying capacity of an
environment for a species.
Density- Dependent
Factors
• Limit size when the number of
individuals reach a certain level
1. Competition for food, water,
space, sunlight, etc.
2. Predation and Herbivory –
populations cycle up and down
Wolf/Moose graph
Moose
Wolves
Density- Dependent Factors
Continued
3. Disease – the denser the
population, the easier it spreads
4. Stress from overcrowding –
can lower birth rates, higher death rates, can
cause parents to neglect young, lead to
emigration
Density -Independent
Factors
• Affect all populations
regardless of size
and density
• Weather, natural disasters,
seasonal change, human interventions (dams,
logging, housing developments)
1. What are the two types of limiting factors?
Density-dependent, density-independent
2. What are the four density-dependent factors?
Competition, predation, disease, stress
3. Define density-independent factors.
Affect population regardless of size.
5.3 - Historical Overview
– For most of human existence, the population
grew slowly because life was harsh. Food was
hard to find. Predators and diseases were
common and life-threatening.
Historical Overview
– Limiting factors kept human death rates high.
Until fairly recently, only half the children
in the world survived to adulthood.
– Because death rates were so high,
families had many children, just to make
sure that some would survive.
Exponential Human
Population Growth
– As civilization advanced,
life became easier, and the human population
began to grow more rapidly.
• What types of things made life easier?
The Predictions of Malthus
– Exponential growth cannot continue
– Two centuries ago, English economist Thomas
Malthus suggested that only war, famine,
and disease could limit human population growth.
– Malthus’s work was vitally important to the thinking
of Charles Darwin.
The Demographic Transition
– Three stages
– Stage I, birthrates and death rates are
high for most of history.
The Demographic Transition
– In Stage II, advances in nutrition, sanitation,
and medicine lead to
lower death rates.
– Birthrates remain high
• Births exceed deaths
• Population increases exponentially.
The Demographic Transition
– During Stage III, as education and living
standards increase, families have fewer
children; population growth slows.
– When the birthrate meets death rate,
growth stops.
The Demographic Transition
– So far, the United States, Japan, and Europe have
completed the demographic transition.
– Parts of South America, Africa, and Asia are passing
through Stage II.
– A large part of ongoing human population growth is
happening in only ten countries, with
India and China in the lead.
1. What are three things Malthus suggested
would decrease population size?
War, famine, and disease
2. Which demographic stage has advances that
result in higher birthrates and lower death
rates?
Stage II
3. In Stage III, why would families have fewer
children?
Higher education and living standards