Ecology

1
Ecology

• 1. Relationships among living things and their
  environment
• 2. Ecosystems, communities, populations

2
Ecosystems

• 1. Complex, interrelated network of living things
  and their nonliving surroundings
• 2. Examples- sloughs, swamps, prairies, lakes,
  estuarine, marine, desert, alpine

3
Community

• 1. All interacting populations within ecosystem
• 2. Community interactions
• a. Competition, population
• size, predation, parasitism
• b. Serve as agents of natural
• selection

4
Population

• 1. All members of particular species living in
  ecosystem
• 2. Members have potential to interbreed
• 3. Population size balance of biotic potential
  environmental resistance

5
Biome

• 1. Large land area with similar environmental
  conditions characteristic communities
• 2. Tropical rain forest, temperate rain forest,
  temperate deciduous, grasslands
• 3. Biosphere- all biomes, Earth

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Succession

• 1. Changes overtime in communities their
  abiotic environment
• 2. Pond to grassland succession
• 3. Primary succession, secondary succession,
  climax community

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Primary Succession

• 1. Pioneer species colonize area where no life
  has been
• 2. Bare rock, sand, glacial pool, lava bed,
  geological uplift
• 3. Early species make more favorable conditions
  for later species

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Secondary Succession

• 1. New community develops after existing
  ecosystem is disturbed
• 2. Forest fire, abandoned farm

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Climax Community

• 1. End point of succession
• 2. Diverse relatively stable community

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Nutrients

• 1. Elements small molecules form all chemical
  building blocks of life
• 2. Macronutrients- required in large quantities,
  H2O, C, N2, P, S, Ca
• 3. Micronutrients- essential, but trace amounts
  needed, Zn, Mb, Fe, Se, I . . .

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Nutrient Cycles

• 1. Biogeochemical cycles- paths nutrients follow
  moving from community to abiotic environment and
  back to community
• 2. Cycling of chemicals within an ecosystem
• 3. Carbon cycle, nitrogen cycle, phosphorus
  cycle, water cycle

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Water Cycle

• 1. All organisms dependent on H2O
• 2. Covers 75 of Earth
• 3. Compartments- surface water, groundwater,
  atmosphere
• 4. Most water returns to atmosphere via
  transpiration

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Carbon Cycle

• 1. CO2 only 0.025 of atmosphere, 7.00 x 1011
  metric tons
• 2. Photosynthesis fixes 10 of CO2 /year to
  organic compounds
• 3. CO2 returns to atmosphere via cellular
  respiration breakdown of organic matter by
  decomposers

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Nitrogen Cycle

• 1. N2 about 78 of atmosphere
• 2. N is essential in plant animal nutrition,
  proteins DNA
• 3. Very few organisms fix N2 to useable organic
  forms
• 4. Cyanobacteria (free-living) N2
  fixing-bacteria (symbiotic in plant roots)

15
Nitrogen Cycle
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Phosphorous Cycle

• 1. Essential for plant growth often limiting
  nutrient
• 2. Most P found as PO4-3
• 3. Only small amounts in soil carried by runoff
  into streams, lakes, oceans
• 4. Deep ocean sediments store most P

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Energy Transfer

• 1. Producers
• 2. Consumers
• 3. Detritus Feeders
• 4. Decomposers
• 5. Food Webs

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Trophic Levels

• 1. Primary producers
• 2. Primary consumers
• 3. Secondary consumers
• 4. Tertiary consumers
• 5. Decomposers

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Primary Producers

• 1. 1o producers- autotrophs
• 2. Make their food molecule
• 3. Foundation of ecosystem communities
• 4. Plants, algae, cyanobacteria

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Consumers

• 1. 1o consumers- heterotrophs consume primary
  producers
• 2. 2o consumers- heterotrophs consume 1o
  consumers
• 3. 3o consumers- heterotrophs consume 2o consumers

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Decomposers

• 1. Breakdown organic matter from bodies of other
  organisms recycle nutrients back into
  environment
• 2. Primarily bacteria fungi

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Primary Productivity

• 1. Mass/energy produced by photosynthetic
  organisms in community
• 2. About 1 of solar energy strikes plant
  converted to chemical energy, carbohydrates
• 3. Gross net primary productivity

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Gross Net 1o Productivity

• 1. Gross- total organic matter produced by
  autotrophs
• 2. Net- GPP minus energy lost in autotroph
  metabolism amount of energy available to
  heterotrophs
• 3. Biomass- combined mass of all living organisms
  in given area

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Comparative Productivity
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Secondary Productivity

• 1. Production of new biomass by heterotrophs
• 2. Heterotroph energy utilization- 50 feces,
  33 cellular respiration, 17 growth

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Food Chains

• 1. Considerable energy is lost at each stage of
  the food chain
• 2. Most food chains are only 3 or 4 steps
• 3. The more productive the community, the longer
  the food chain

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Lake Food Chain

• 1. Algae cyanobacteria- 1000 calories
• 2. Secondary heterotrophs- 150 calories
• 3. Smelt- 30 calories
• 4. Trout- 6 calories
• 5. Human- 1 calorie

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Producers

• 1. Autotrophs- produce food for themselves
• 2. Photosynthesis- plants, plant-like protists,
  cyanobacteria convert light energy to chemical
  energy, glucose

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Production

• 1. Net primary production- all stored chemical
  energy per area per time, J/m2/yr J/m2yr
• 2. Biomass- dry mass of organic material produced
  per area per year, kg/m2/yr kg/m2yr
• 3. Influenced by available nutrients, light,
  water, temperature

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Consumers

• 1. Heterotrophs- rely on other organisms to
  produce food
• 2. Trophic levels- primary, secondary, tertiary.
  . .
• 3. Primary consumes producer, secondary consumes
  primary, tertiary consumes secondary. . .

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Detritus Feeders

• 1. Consume refuse of life, molts, fallen leaves,
  waste, dead bodies
• 2. Extremely complex network includes earthworms,
  mites, protists, centipedes, some insects
  crustaceans, nematods, vultures
• 3. Extract some energy from dead organic matter
  excrete it in more decomposed state

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Food Webs

• 1. Food chain- linear relationship of who eats
  whom in community, rare
• 2. Food web- many interconnecting food chains in
  community, more common
• 3. Energy pyramid- describes transfer of energy
  from one trophic level to another, entropy

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Energy Pyramids

• 1. 10 rule- only 10 of energy in trophic level
  is transferred to next level
• 2. For 1000J of primary production, primary
  consumers receive store 100J, secondary
  consumers receive store 10J, tertiary
  consumers receive store 1J

34
Homeostasis

• 1. Maintenance of constant physical chemical
  conditions within a living system
• 2. Physical chemical changes occur but only
  within a range
• 3. Dynamic equilibrium
• 4. Feedback mechanisms

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Feedback

• 1. Positive feedback events are self limiting
  rare in nature
• 2. Negative feedback systems
• a. Erythropoietin blood O2 content
• b. Antidiuretic hormone H2O balance
• c. Insulin blood sugar levels

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Negative Feedback
37
Positive Feedback
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