ECOLOGY
CH. 1 & 2
ECOLOGY
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Def: the study of how living things interact with their
environment
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Habitat – where an organism gets the things it needs to
survive
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Biotic Factors  Living
Abiotic Factors  Non-living
Levels of Organization
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Organism – individual
Population – members of same species
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Species – similar organisms that are capable of producing offspring
that are similar to parents
Community – all the populations in an area
Ecosystem – the community plus non-living parts of the
area
Biosphere – all the ecosystems of the world
Studying Populations
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Population – number of individuals
Population Density – individuals/ unit of area
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How crowded it is
Methods
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Direct Observation – actually seeing
Indirect Observation – seeing evidence without seeing
individuals
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Ex.
Sampling – average of smaller areas to estimate total
population
Mark and Recapture
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(# Marked X # captured 2nd time)/ # caught 2nd time with marks
Studying Populations
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Changes to population
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Limiting Factors – environmental factors that
prevent a population from increasing
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Birth rate vs. Death rate
Immigration (in) vs. Emigration (exit)
Ex.
Carrying Capacity – the maximum number of
individuals an area can support
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Based on limiting factors
Interactions Among Populations
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Niche – how an organism interacts and uses its habitat
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Adaptations – Physical or behavioral characteristics that make
an organism more likely to survive (better able to use habitat)
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Keeps niches different from other species
Natural Selection – survival of the fittest
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The role or job of an organism
Forms adaptations
Competition – struggle for limited resources
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Hurts both species
Interspecific – two different species
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Ex.
Intraspecific – two members of same species
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Ex.
Interactions Among Populations
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Predation – A specie hunts, kills, and eats
another
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Predator Adaptations:
Prey Adaptations:
Mutualism – Both species benefit (+/+)
Commensalism – One species benefit, the
other is unaffected (+/0)
Parasitism – one species (parasite) lives off
from another (host) causing it harm
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Doesn’t usually kill host
Energy Flow through an Ecosystem
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Food Chain  single path
Food Web  many, interconnected food
chains
Trophic Levels
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Producer – autotrophs
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Photosynthesis
Consumer – heterotrophs
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Primary consumer – herbivores
Secondary Consumer – carnivore
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Omnivore – sometimes primary, sometimes secondary
3rd level, 4th level etc.
Scavengers – carnivore that eats the already dead
Energy Flow through an Ecosystem
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Decomposers – detritivores
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Energy Pyramid – shows total amount of energy in
each trophic level for an ecosystem
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Most energy in producers
10% is passed onto next trophic level
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Almost all energy passes here last
Exception: stored energy in fossil fuels
Each trophic level has less individuals
Not many top carnivores
Limit to number of levels in food chain
Biological Magnification – a chemical (pollutant)
becoming more concentrated as it is passed through
the food chain
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DDT and Bald Eagles
MATTER CYCLES
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Hydrologic – Water Cycle
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Evaporation – liquid to gas (water vapor)
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Condensation – water vapor to liquid
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Purifies; only water goes up
Transpiration –trees/plants evaporating water
Clouds & fog
Precipitation
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Rain, snow, sleet, hail, ice
What happens next?
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Surface Run-off – ditches  streams  lakes, rivers  oceans
Aquifer – ground water
Ends up in living organisms
Evaporation – returns directly to atmosphere
MATTER CYCLES
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Carbon Cycle
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Found in atmosphere as Carbon Dioxide (CO2)
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Needed by organisms to form organic compounds
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.03%
Linked to global warming as environmental concern
Converted by plants through the process of photosynthesis
Returned to atmosphere
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Respiration – breaking down carbon compounds for energy
Combustion – burning fossil fuels or plant products
Double Whammy! – Deforestation
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Can’t take carbon out
Burning puts carbon in
Fossil Fuels – carbon stored deep in Earth
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Past organisms
Oil, natural gas, coal
MATTER CYCLES
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Nitrogen Cycle
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Found in the air as atmospheric nitrogen (N2)
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78% of air; most abundant substance
Can NOT be used directly by most organisms
Nitrogen fixation – changing atmospheric nitrogen into a
usable form
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Needed by organisms to make proteins
Rhizobium (bacteria) or lightning
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Found on root nodules in Legumes (alfalfa, clover, beans)
Atmospheric nitrogen is changed into ammonia (NH3) or nitrates
(NO4)
Can be added to soil through fertilizers or decomposition of
organisms
Denitrification changes nitrogen compounds back into
atmospheric nitrogen by bacteria.
Succession
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Read Section 2-5 (p. 76-78)
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Read Silently
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Write down Topics or Objectives you should be able to accomplish
after reading
Make a list of key terms and key ideas (these are the notes)
Topics (Objectives):
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Take a break after each section and ask, “what did I just read?”
Know the definition of succession
Know the difference between primary and secondary succession
Know the order of change that occurs during succession
Key Terms:
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Succession, pioneer species, biome
Succession
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Def: the change of an ecosystem back to its climax
community
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Climax community – the natural state of an ecosystem
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Pioneer species – first to arrive after disturbance
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Based on climate (weather, temp), altitude, soil etc.
Biomes
Lichens, weeds
Animation
Primary – no pre-existing ecosystem
Secondary – return after disturbance
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Can be human or natural disturbances.  ex: