Download Ch 4, 5, 6, Notes

Chapters 4, 5, 6
Communities, Ecosystems, Biomes,
Populations, Biodiversity, and
Conservation
Vocabulary
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Keystone Species
Habitat
Niche
Predation
Symbiosis
Mutualism
Commensalism
Parasitism
Population
Carrying Capacity
Exponential Growth
Limiting Factor
Density-Dependent
Density-Independent
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Ecological Succession
Primary Succession
Pioneer Species
Secondary Succession
Climax Community
Biosphere
Biodiversity
Geosphere
Hydrosphere
Atmosphere
Sustainability
Renewable Resource
Nonrenewable Resource
Greenhouse Effect
Standards: 6A.1, 6A.2, 6B.1, 6B.2, 6C.1, 6D.1
Objectives:
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Summarize how limiting factors affect
population size.
Classify various types of limiting factors.
Summarize the processes of primary and
secondary succession.
Summarize how various aspects of an
ecosystem are naturally maintained.
Summarize how various human activities affect
the geochemical cycles and processes of Earth.
Keystone Species
• Keystone Species – single species that is vital
to ecosystem stability.
– Affects the survival and abundance of many other
species in its community.
Habitat and Niche
• Habitat – area where an organism lives 
HOME
• Niche – role or position that an organism has
in its environment  JOB
– How an organism meets its own needs.
– Two species with same niches cannot coexist in
the same habitat
Relationships Among Organisms
• Organisms that live together constantly
interact  shapes an ecosystem.
• Types of Interactions:
– Competitive
– Predator-Prey
– Symbiotic  3 types
Competition
• Two or more organisms need the same resource at
the same time.
– Same species or different species.
– Organisms typically occupy the same niche.
– Compete for mates, food, space, etc.
– Strong survive and weak die  “Survival of the Fittest”.
Predation
• Predation – the act of one organism consuming
another organism for food.
– Most species get their food by eating other
organisms.
– Predators affect the size of prey populations.
– Predator – the hunter
– Prey – the hunted
Predation
• Population size of predators in an ecosystem is
directly affected by the size of the prey population.
• Fluctuations are predictable.
– Prey increases  predator increases
– Prey decreases  predator decreases
How Organisms Reduce Predation
Symbiotic
• Symbiosis – close relationship that exists
when two or more species live together 
coevolution.
– Types:
• Mutualism
• Commensalism
• Parasitism
Mutualism
• Mutualism – both organisms benefit each
other.
Commensalism
• Commensalism – one organism benefits and
the other neither helped nor harmed.
Parasitism
• Parasitism – one organism benefits at the
expense of another.
– Parasite  lives on or in an organism & feeds
– Host  organism that nourishment is taken from
• Usually the host is not killed
Types of Interactions
Interaction
Species A
Species B
Competition
Harmed
Harmed
Predation &
Parasitism
Benefited
Harmed
Mutualism
Benefited
Benefited
Commensalism
Benefited
Unaffected
Population
• Population – group of organisms belonging to
the same species that live in the same area.
– Described based on their:
• Size  # of individuals
• Density  # of individuals per area of space
• Distribution  arrangement
Review: Calculate Population Density
2m
4m
Population Growth
Population size affected by:
• Births
• Deaths
• # Leaving
• # Entering
Exponential Growth
• Exponential Growth – growth pattern in
which the individuals in a population
reproduce at a constant increasing rate.
– Under ideal conditions with unlimited resources.
– Graph  J-shape
Exponential Growth
Carrying Capacity
• Carrying Capacity – maximum number of
individuals of a particular species that
environment can support.
Logistic Growth
• Logistic Growth – includes the influence
of limiting factors on population growth
• Graph  S-shape
Regulation of a Population
• Limiting Factor – any abiotic or biotic factor that
restricts the numbers, reproduction, or distribution
of organisms  slows population growth.
– Examples: sun, climate, temperature, water, nutrients,
fire, soil, space, etc.
– A population is affected by limiting factors.
Types of Limiting Factors
• Density-dependent  occur more quickly in a
crowded population than a small one.
– Triggered by increases in population size
– Examples: competition, predation, parasitism,
disease.
• Density independent  occur regardless of
the population size.
– Reduces the size of all populations in the area by
the same proportion.
– Mostly abiotic factors, human activities, natural
disasters.
Types of Limiting Factors
• Abiotic Factors  may be chemical or physical.
– Examples: water, N, O, salinity, pH, nutrients,
precipitation.
• Biotic Factors all living components.
– Examples: bacteria, fungi, plants, animals.
• Changes in abiotic or biotic factors may decrease
OR increase the size of a population.
Ecological Succession
• Ecological Succession – series of changes in an
ecosystem when one community replaces another
community.
– Continual process of change and replacement
because of competition.
– Occurs in ALL ecosystems.
– Two Types:
• Primary  slower process
• Secondary  faster process
Ecological Succession
Primary Succession
• Occurs in an area that has not previously been
inhabited.
– Examples: Volcanic eruption exposes bare rock, glaciers
retreat exposing bare rock, or a city street.
– Pioneer species (first organisms) such as lichens (fungi
and algae), mosses, & bacteria can grow without soil.
– Pioneer species break rock into soil.
– Fewest habitats for organisms.
– Nutrients and soil added over time.
– Small plants (ferns and shrubs) grow breaking rock into
more soil.
Primary Succession
– Plant seeds germinate and grow.
– Over time more species grow and die 
decomposition = more nutrients in soil and larger
plants grow.
– Plants change = animals change
– Communities replace other communities
– Climax Community – stable, mature forest
community where there is little change in the
composition of species.
Primary Succession
Secondary Succession
• Reestablishment of damaged ecosystem with
well-formed soil.
– Examples: abandoned farmland, vacant lots, clearcut forests, areas produced by forest fires.
– Similar to primary succession in later stages (after
soil has formed).
– Disturbance occurs such as fire, hurricane, human
activities and community is destroyed.
– Ecosystem interacts to restore original conditions.
Secondary Succession
Review: Primary or Secondary Succession
Earth as a System
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Biosphere  all living organisms
Geosphere  solid, rocky part (core  crust)
Hydrosphere  water
Atmosphere  gases
• All systems must interact efficiently to maintain
an ecosystem.
Greenhouse Effect
• Greenhouse Effect – normal warming effect
when gases trap heat in the atmosphere.
– Greenhouse Gases (CO2, O2, methane, water vapor)
 trap heat energy & maintain temperature on Earth.
CO2 in Atmosphere
Atmospheric
CO2
Greenhouse
Effect
Avg.
Global
Temps.
Plants
Rate of
Photosynthesis
CO2
absorbed
by plants
Atmospheric
CO2
• Higher temperatures and shifting climate patterns
may change areas where crops grow best and
affect the makeup of natural plant communities.
• Increase CO2 = increase rate of photosynthesis
Biodiversity
• Biodiversity – variety of organisms living in an
area at the same time  includes # of different
species and population size of each species.
– Genetic diversity – genes & pattern of variation
– Species diversity – variety & abundance of species
– Ecosystem diversity – variety of habitats
• Humans depend on Earth’s biodiversity & ecosystem
resources (such as clean water & air) to survive.
Biodiversity is highest near equator and in the
ocean along the coasts in the Western Pacific.
Threats to Biodiversity
• Habitat Destruction
– Humans destroy & convert complex natural ecosystems
into simple systems that do not support many species.
– Rainforests  1% lost each year due to logging &
agriculture
– Wetlands destroyed  “waste areas”
– Habitat fragmentation – prevents organism from
accessing its entire home range. Solution  build land
bridges or corridors.
Threats to Biodiversity
• Invasive Species
– Living organisms not native to an ecosystem.
– Threats  decrease biodiversity, preying on native
species, competition, disease, changing food webs, etc.
Fire Ant
Burmese Python
Nile Crocodile
Threats to Biodiversity
• Pollution
– CO2 & other greenhouse gases, human wastes,
chemicals
Threats to Biodiversity
• Human Population Growth
– Exponential growth world-wide
– Population reaches Earth’s carrying capacity due to:
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Water shortages
Waste removal and pollution
Food resources and land usage
Imbalance of biogeochemical cycles
Threats to Biodiversity
• Overharvesting
– Resources are consumed at an unsustainable rate
– Examples: overhunting, excessive logging, overfishing
Ecological Restoration
• Process of assisting the recovery of an ecosystem
that has been destroyed.
Human Impact
• Sustainability – humans survive indefinitely 
balance between resources and carrying
capacity.
• Factors that affect sustainability of humans:
– Population growth  increased diseases, food &
water shortage
– Pollution & waste
– Consumption of resources  demand increases
• Renewable - production = consumption
– Food & water
• Nonrenewable - production = consumption
– Fossil fuels (coal, oil, natural gas)