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Ecology
And the Human Interaction with the environment
Levels of Interaction
 Species – a group of organisms that can breed and
produce fertile offspring
 Population – a group of organisms/ individuals of
the same species that live in the same area.
 Communities – assemblages of different
populations that live together in a defined area.
Interactions con’t
 Ecosystem – biotic and abiotic factors together in
one area
 (biotic – living factors) (abiotic – temp, amount of
light, amount of water, nutrients available, etc)
 Biome – a group of ecosystems that have the same
climate and dominant communities
 Ex. Tundra, taiga, rainforest, desert, deciduous forest
What shapes and
ecosystem
 Biotic vs abiotic – together these factors determine
the survival growth of an organism and the
productivity of the ecosystem in which the
organism lives.
 The area they live is its habitat.
 Niche – the full range of physical and biological
conditions in which an organism uses those
conditions. (an organisms job in the environment.)
Population Growth
 Factors that effect population growth
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Birth
Death
Immigration
emmigration
Exponential growth
 Occurs when the individuals in a population
reproduce at a constant rate.
 Under ideal conditions with unlimited resources, a
population will grow exponentially.
Logistic Growth
 When resources become less available the growth of a
population slows or stops.
 The number of organisms the environment can support
is called the carrying capacity
 If a population exceeds the carrying capacity
significantly the population will collapse.
Biodiversity
 The sum total of the genetically based variety of all
organisms in the biosphere.
 Biodiversity in one of Earth’s greatest natural
resources. Species of many kinds have provided us
with many kinds of foods, medicines, industrial
products, etc.
 The more biodiversity in an area, the more stable
the area.
Community Interactions
 Competition
 Predation
 Symbiosis
 Mutualism
 Commensalism
 Parasitism
Energy Flow
 We have a constant input of energy from the sun –
This is the main energy source for all life on Earth.
 Autotrophs/ producers – use solar/ light/
inorganic energy and convert is to organic
compounds.
 Photosynthesis/ chemosynthesis
Consumers
 Heterotrophs
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Herbivores – eat only plant material
Carnivores – eat only animals
Omnivores – eat both plant and animals
Detritivores – eat the remains and other dead matter
Decomposers – break down organic material
Feeding relationships
 Energy flows through an ecosystem in one direction
from the sun to autotrophs and then to
heterotrophs.
 Food chains
 Food webs
 Trophic levels – pyramid with autotrophs at the
bottom
Ecological pyramids
 Energy pyramid
 Biomass pyramid
 Pryamid of numbers
Cycles of matter
 Water cycle
 Evaporation, transpiration/ root uptake
 Condensation/ precipitation/ runoff/ seepage
 Nutrient cycles
 Carbon Cycle
 Photosynthesis/ respiration
 Nitrogen cycle
 Nitrogen fixation/ denitrification
 Phosphorous cycle
Nutrient limitation
 Primary productivity – rate at which organic matter
is created by producers
 This rate is effected by the amount of available
nutrients (if in short demand growth is limited) –
thereby becoming a limiting factor
 When an ecosystem receives a large input of a limiting
nutrient (ie fertilized field runoff into streams) can
cause and immediate increase in populations (ie –
algal blooms, red tides)
Succession
 Ecosystems are constantly changing in response to
natural and human disturbances. As an ecosystem
changes, older inhabitants gradually die out and
new organisms move in, causing further changes in
the community.
 Primary succession – no soil exists to start
 Pioneer species – mosses and lichens (helps build up
soils)
Secondary succession
 A disturbance or change without removing the soil – like
a wildfire and plowed land.
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Grasses
Shrubs
Small trees
Forest
 (can take over ponds into land)
The role of climate
 Weather is the day to day condition of the Earth’s
atmosphere at a particular time and place
 Whereas climate refers to the average, year after
year conditions of temperature and precipitation in
a particular region.
The effect of latitude on climate/
heat transport
 As a result of differences in latitude and thus the
andgle of heating, Earth has three main climate
zones; polar, temperate and tropical.
 Heat transport
 Ocean currents
 Wind patterns
– trade winds
and such
Biomes
 Climate vs microclimate
 Major biomes –
 Aquatic ecosystems
 Freshwater ecosystems
 Flowing water ecosystems
 Standing water ecosystems
 Freshwater wetlands
Biomes
 Estuaries
 Wetlands formed where rivers meet the seas
 Salt marshes are dominated by salt tolerant grasses
above the tide line and by seagrasses underwater.
 Marine ecosystems
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Photic zone
Aphotic zone
Intertidal zone
Costal ocean
Coral reef
Human threats to the
Environment
 Overpopulation!
 Global Warming
 Hole in the Ozone
 Acid Rain
 Decrease in Biodiversity
 Treating renewable resources as non renewable
resources.
 Foreign/ non native species
 Insecticides/ biomaginification
What can we do?