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Ecology - PowerPoint PPT Presentation

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Ecology. 5 Levels of Ecological Organization. Species - organisms that can interbreed and produce fertile offspring Population - all the members of 1 species in an area Community - every species in an area Ecosystem - many communities

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5 levels of ecological organization
5 Levels of Ecological Organization

  • Species- organisms that can interbreed and produce fertile offspring

  • Population- all the members of 1 species in an area

  • Community- every species in an area

  • Ecosystem- many communities

  • Biosphere- The entire region of Earth where living things can be found (many ecosystems)

What is ecology
What is Ecology?

  • Study of the interaction between organisms and their environment

  • Within an ecosystem there are two main components.

    habitat- place where organism lives

    community- ALL the species in habitat

Species interaction
Species Interaction

  • Many interactions take place between species in a community.

    i.e.) predator and prey

  • Each organism plays a certain role in the community.

  • Niche- role of organism in which it interacts with other species and its environment (i.e. its job)

Abiotic vs biotic factors
Abiotic vs. Biotic Factors

  • Abiotic- “non-living” components

    -ex) temperature, light, water, nutrients, boats

  • Biotic- “living” species

    -ex) sea turtle, sea grass, coral, fish, humans


  • Biodiversity-The number of different species in an ecosystem.

  • More plants = more animals

  • More biodiversity = healthier ecosystem.

What determines biodiversity of ecosystem
What Determines Biodiversity of Ecosystem?

  • Size

  • Latitude – Closer to equator more diverse.

    a) More sunlight and longer growing season

    b) More producers (plants)

    Why do we call plants producers?

    c) More producers = more consumers

  • Precipitation (i.e. rainfall)

Conditions for life
Conditions for Life

  • For an ecosystem to sustain life, it must have:

    1) Constant source of energy (sun).

    2) Living system that converts sun’s energy into organic molecules.

    -Producers (plants) Why?

    3) Cycling of nutrients between organisms and environment (water, carbon dioxide, nitrogen, oxygen).

    4) Decomposers return unused nutrients to the environment.

Photosynthesis equation
Photosynthesis Equation


Producers are considered autotrophs, or “self-feeders” because they can make their own “food.”

Consumers are considered heterotrophs, or “other-feeders” because they have to consume their food.

Nutritional interactions
Nutritional Interactions

  • All ecosystems must have interactions between producers, consumers, and decomposers.

  • Producers (autotrophs)

  • Consumers (heterotrophs)





Energy flow in an ecosystem
Energy flow in an ecosystem

  • Energy flows through an ecosystem from the sun to producers to consumers.

  • ***Arrows show the way the energy flows.

Who eats who
“Who Eats Who”…

  • Food chain- straight line sequence shows simple feeding relationships

  • Notice the direction of the arrows!

  • Sun

  • Producers

  • Primary consumers

  • Secondary Consumers

  • Tertiary Consumers

  • Food web- illustrates how the many food chains in an ecosystem are related

  • Primary consumers?

  • Secondary consumers?

  • Tertiary consumers?

  • Where would

    decomposers fit in

    this food web?

How many trophic levels are possible
How many trophic levels are possible…?

  • Trophic means “feeding”

  • Trophic levels -levels of feeding from producers (plants) to the consumers

    • Few ecosystems have more than 4 or 5 trophic levels

    • Energy diminishes at each level because it is used for life’s processes.

  • Energy pyramids- show amount of energy at each trophic level.

  • These are not food pyramids!!

Pyramid of energy
Pyramid of Energy

  • Which level has the most energy AVAILABLE?


  • Producers (most energy available)-autotrophs

  • Primary consumers-herbivores

  • Secondary consumers-small carnivores

  • Tertiary consumer-large carnivores

  • Energy is given off at every level as waste heat by the organisms as they survive.

How do organisms obtain nutrients
How do organisms obtain nutrients?

  • Although energy moves through ecosystems in a one-way direction, nutrients are recycled.

  • Three basic nutrient cycles are present in all ecosystems allowing organisms to obtain needed nutrients to function effectively.

Nitrogen cycle
Nitrogen Cycle

  • The atmosphere contains 80% nitrogen gas (N2).

  • However, this nitrogen can not be used by most living things.

  • Bacteria are the only organisms that use nitrogen gas directly from the atmosphere.

  • They can fix nitrogen for plants to use by converting it into ammonia.


DNA and proteins

Nitrogen cycle terminology
Nitrogen CycleTerminology



  • Nitrogen fixation- nitrogen gas

    in atmosphere converted to ammonia (bacteria in soil,


  • Nitrification- bacteria converting ammonia to nitrate (another form of nitrogen)

  • Assimilation- absorption of ammonia and nitrate by plants

Nitrogen fixation



Nitrogen cycle terminology1
Nitrogen Cycle Terminology


  • Ammonification- decomposers (bacteria and fungi) break down of dead organisms and waste and return nitrogen to soil as ammonia.

  • Denitrification- conversion of ammonia back to nitrogen gas (decomposers).




Why is the nitrogen cycle important
Why is the nitrogen cycle important?

  • Why is nitrogen important to living things?

  • How do plants obtain nitrogen?

  • Why are bacteria SO important to the nitrogen cycle?

  • How do we obtain nitrogen?

  • Nitrogen cycle movie with QUIZ

Water cycle
Water Cycle

  • Driving force is the sun and gravity.

  • Consists of the alternation between evaporation and precipitation.

  • Most water returned to the atmosphere comes from evaporation from the oceans.

Water cycle terminology
Water Cycle Terminology

  • Water vapor- gaseous form of water in atmosphere

  • Evaporation- liquid water from bodies of water becomes gas returned to atmosphere.

  • Transpiration- loss of water by land plants

  • Condensation- process which water molecules gather in atmosphere “change from gas to liquid” when cooled.

  • Precipitation- water falls from atmosphere to ground (rain, snow, sleet, or hail)

Water cycle1
Water Cycle

What is missing here?

Why is the water cycle important
Why is the water cycle important?

  • Water is the most important nonliving (abiotic) component of an ecosystem.

  • Water essentially determines what organisms we find in an ecosystem.

  • What is the major difference between the tropical rainforest and the desert? Why?

Carbon cycle
Carbon Cycle

  • Carbon cycles between the living organisms and the non-living components of ecosystem.

  • Plants are of great importance to the carbon cycle!!--photosynthesis

  • Carbon exists in the atmosphere as carbon dioxide (CO2)

  • Why do living things need carbon?

Carbon cycle terminology
Carbon Cycle Terminology

  • Photosynthesis- process where sunlight, CO2 and H2O is used to make carbs.

    CO2 + H2O + sunlight (energy)  glucose (carb) + O2

  • Respiration- process by which animals use carbs, taking in O2 given off by plants and give off CO2


    glucose (carb) + O2  CO2 + H2O + energy to live

  • Decomposition—breakdown of dead organisms and waste, returning carbon to the soil and atmosphere

  • Fossil fuels- formed by pressure applied to dead organisms that are buried in sediment. They are carbon and release CO2 when burned.

  • Combustion- burning of fossil fuels

  • Carbon cycle video with QUIZ

Why is the carbon cycle important
Why is the carbon cycle important?

  • Organic macromolecules -energy for living organisms (carbohydrates), cell membranes (lipids), DNA/RNA, and proteins.

  • ***Humans in the United States are altering this cycle

    • Deforestation

    • CO2 is a greenhouse gas

    • Burning too many fossil fuels releases extra CO2 into the atmosphere creating global warming due to increased greenhouse effect.

  • The greenhouse effect is normal. Global warming is abnormal amounts of the greenhouse effect.

  • Greenhouse effect video clip

How competition effects ecosystems
How competition effects ecosystems

  • Sometimes two species will compete.

  • No two species can occupy the exact same niche (job) for a long period time.

  • Only one species wins. This is called competitive exclusion.

What if no one wins
What if no one wins?

  • In some species interactions, neither species wins.

  • This results in close, long term associations within an ecosystem called symbiotic relationships.

3 kinds symbiotic relationships
3 Kinds Symbiotic Relationships

  • +=helped

  • - = harmed

  • 0=neither

  • Parasitism (+/-)

  • Commensalism (+/0)

  • Mutualism (+/+)

Evolution and ecology
Evolution and Ecology

  • Symbiotic relationships cause species to evolve in response to each other.

  • Ex) Flowers pollinated by nocturnal moths.

  • This is called coevolution.

  • Ant and Fungus Symbiosis

Changing Ecosystems

  • Changes are a natural part of any ecosystem.

  • Succession: regular development of an ecosystem which leads to gradual replacing of species in a community by others.

  • Succession

Ecosystem stability
Ecosystem Stability

  • Does succession ever end?

  • Climax community

  • Stability - ability of an ecosystem to resist change when a disturbance occurs.

  • Biodiversity tends to promote stability.

Ecosystem stability1
Ecosystem Stability

  • Keystone species- species that are crucial to the stability of an ecosystem.

  • If members of a keystone species die, then the entire ecosystem can collapse.

  • i.e. sea otters- keep sea urchins in check, which would take over the kelp beds without the otters

Ecosystem stability2
Ecosystem Stability

  • Invasive/introduced species destroy ecosystems.

  • They are species that are brought by humans accidentally or purposefully from other places and take hold

  • They multiply unchecked due to lack of predators in new place they are moved to.

  • Ex: Asian longhorn beetle, Zebra mussels

Population dynamics world populaton clock
Population DynamicsWorld Populaton Clock

  • Population-a group of organisms of the same species that occupy a given area.

  • Living things reproduce.

  • If environmental conditions are “favorable,” then the number of individuals in population should increase from one generation to next.

Biotic potential
Biotic Potential

  • Under favorable conditions, a species may reach its biotic potential.

  • Biotic potential- highest reproduction rate possible for a species under “ideal” conditions.

    Ex) Houseflies

    -lay over 100 eggs at once

    -can reproduce at 1 month old

    -after 7 generations,

    one fly = 15 billion flies!!!

Exponential growth
Exponential Growth

  • Population grows rapidly to infinitely high number.

  • Represented by “J curve”

  • This does NOT describe real-life.



Logistic Growth

  • Real populations can only grow exponentially for short spans.

  • Environmental resistance limits size of a population.

  • Logistic curve- real population growth looks like this and is“S” curve

Carrying capacity
Carrying Capacity

  • Population grows slowly, increases, levels off.

  • Carrying capacity- total # of individuals that can be supported by the environment in a particular area

  • Earth has 6.6 billion people…how many more can it support?

  • Population Crash

Population size growth rate
Population Size- Growth Rate

  • Birth rate- # individuals born

  • Death rate- # individuals die

  • Immigration- # individuals move in

  • Emigration- # individuals move out

  • If…




  • Population growth video clip

Factors affect growth rate size of population
Factors Affect Growth Rate Size of Population

  • Environmental resistance- “limiting factors” stop population from reaching biotic potential

  • Population density -the number of individuals in a population for a certain area.

Types of limiting factors
Types of limiting factors:

  • Density independent factors- don’t depend on the density of individuals

    i.e.) usually abiotic- natural disasters, pollution

Types of limiting factors1
Types of limiting factors:

  • Density dependent factors – factors that affect a population as it increases in density

    i.e.) Disease (flu/colds winter)



    interspecific (between different species)

    intraspecific ( within same species)

2.) Density dependent- affect population as

a result of # of individuals

Ex) disease, predation,


Problems with overpopulation
Problems with Overpopulation

  • Humans, more than anything else, are affecting the stability of Earth.

  • 1.) Decrease in food supply

    -over fishing

    -agricultural land/residential

  • 2.) Energy shortage-

    - renewable/nonrenewable resources

  • 3.) Destruction natural resources

    -topsoil, groundwater, species

  • 4.) Pollution


    -air (acid rain, ozone depletion due to CFC’s in aerosol cans, global warming due to

    burning and deforestationCO2

    -production of tons of solid waste

b) CFCs

  • Ozone Shield:

  • Ozone (O3) in the atmosphere absorbs harmful UV light.

  • Since the late ‘70s, scientists have discovered that the ozone layer over Antarctica has decreased by as much as 60 %

  • Ozone: Good Up High, Bad Near By

  • Human inputs?

  • chlorofluorocarbons(CFCs)

  • Problems?

  • UV light is a mutagen, which can cause skin cancer

  • Cataracts


  • Biomes are groups of terrestrial ecosystems that have the same climate and dominant communities.

  • 3 types of biomes:

    • Temperate: seasonal

    • Tropical: by equator and hot year round

    • Arctic: far from equator and cold year round

  • You have forests, deserts and grasslands in these different areas


  • Biomes:

    • Temperate forests (deciduous)

    • Grasslands

    • Tropical forest

    • Tropical desert

    • Tropical grassland (called savannahs)

    • Arctic forests (taiga)

    • Arctic grasslands (tundra)

Aquatic lifezones
Aquatic Lifezones

  • Aquatic lifezones are aquatic ecosystems.

  • Freshwater or saltwater.

  • Freshwater

    • Wetlands are very important ecosystems.

    • Bogs, swamps or marshes.

    • Rivers

    • Ponds

    • Estuaries (wetlands where river meets sea)

    • Mangrove swamps

  • Saltwater (Marine)

    • Coral Reefs

    • Intertidal zone

    • Open ocean

    • Biomes-22min