Download Ecology Class Notes

Ecology
Chapter 3.1 to 3.3
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What is Ecology?
• Ecology – the study of interactions among
organisms and between organisms and their
environment
• Biosphere – the largest of the areas of the earth
containing the portion of the planet that life
exists, including land, water and air
(atmosphere)
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Levels of Organization
Ranges in
complexity
from single
individual to
entire
biosphere.
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Levels of Organization
• Individual – one organism
• Population – group of individuals that belong to the
same species and live in the same area
– Species - a group of individuals so similar to one another
that they can breed and produce fertile offspring.
• Community –different populations that live together is
a defined area
• Ecosystem – all the organisms that live in a similar
area along with the nonliving material
• Biome – group of ecosystems (similar climate)
• Biosphere – entire earth
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Ecological Methods
• Scientists use 3 basic methods to conduct
ecological research.
1. Observing – qualitative and quantitative
observations
2. Experimenting – used to test hypotheses, can set
up artificial environments and manipulate conditions
3. Modeling – models are made to study events that
have occurred over large time periods, or are large
in scale
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Interactions Among
Organisms- Energy Flow
• Sunlight is the main energy source for life on Earth
• Producers – autotrophs (make their own energy using
the sun)
– Photosynthesis – using light to produce energy /
food
– Chemosynthesis – using inorganic molecules to
produce energy / food
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Energy Flow
Photosynthesis
Chemosynthesis
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Energy Flow
• Consumers – heterotrophs (cannot make their own
energy)
– Herbivores – consume plants
– Carnivores - consume meat
– Omnivores – consume both
– Detritivores –feed on dead or decaying matter
• earthworms, mites, crabs, snails
– Decomposers – break down organic matter
• bacteria & fungus
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Energy Transfer /
Feeding Relationships
• Energy flows in one
direction
• Food Chain- series of steps
where energy is transferred
by eating and being eaten
• Trophic Levels – each step
in a food chain
• Food Web –links all food
chains in ecosystem
together
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Food Chain vs. Food Web
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Ecological Pyramids
• Diagram that shows relative amounts of energy or
matter contained within each trophic level in a food
chain or food web for an ecosystem
1. Energy Pyramid – energy available at each
trophic level
- 10% rule
2. Biomass Pyramid – amount of living
tissue/potential food available in each level
3. Pyramid of Numbers - number of individual
organisms
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Examples of Pyramids
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Recycling in the Biosphere
• Water Cycle
– Evaporation, precipitation, condensation,
transpiration, run-off, ground water
– Video
– Song
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Nutrient Cycle
• Carbon Cycle –
carbon fixation,
CO2
• Photosynthesis,
respiration
• Fossil fuels
• Human Activities
– Mining, cutting
forests, burning
fossil fuels
Video
Video
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Biogeochemical Cycles
• Nitrogen cycle – nitrogen fixation (bacteria),
denitrification
• Video
• Video
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Biogeochemical Cycles
• Phosphorus Cycle
– Does not enter
atmosphere.
– In land, rocks, soil
and ocean sediment
as inorganic
phosphate.
– Will dissolve in
water.
Video
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Nutrient Limitation
• Primary Productivity – rate of production of
organic matter by producers
– Amount of available nutrients.
• Limiting Nutrients – nutrient that limits
productivity when scarce.
• Aquatic ecosystems – large input of limiting
nutrient can cause an increase of algae or
producers = algal bloom
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Chapter 4.2
What shapes an ecosystem?
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Biotic Factors
• Biological influences on organisms within an
ecosystem
– Include all living organisms.
– Cast of characters that an organism might interact
with
– Bullfrog:
• Plants and algae as a tadpole
• Herons that eat adult bullfrogs
• Other species that compete with frog for space and food.
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Abiotic Factors
• Physical or non-living factors that shape an
ecosystem
– Climate:
• Temperature, precipitation, humidity.
– Wind, nutrients availability, soil type, sunlight
• Biotic and Abiotic factors together determine
the survival and growth of an organism and
productivity of an ecosystem
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Niche
• An organisms habitat is its address, its niche is
its occupation.
• Full range of physical and biological conditions
in which it lives and the way the organism uses
these conditions.
– Type of food it eats, how it obtains food, what other
species use the organism as food.
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Community Interactions
• Competition- when organisms of
same or different species attempt
to use an ecological resource in
the same place and at the same
time.
• Resource- necessity of life
• Competitive Exclusion PrincipalNo two species can occupy the
same niche in the same habitat at
the same time.
– Losing organism will fail to
survive.
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Community Interactions
• Predation- One organism captures and feeds
on another organism.
• Symbiosis- “living together”
– Mutualism- both benefit
• Flowers and insects
– Commensalism- one benefits, other is neither
helped nor harmed.
• Barnacles on marine animals
– Parasitism- one organism lives on or inside another
and harms it.
• Tapeworms, fleas, ticks, lice
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Label each
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Ecological Succession
• Predictable changes that occur in a community
over time.
• 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 change.
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Ecological Succession
• Primary Succession -occurs on surfaces where no soil exists
– Volcanic eruptions, bare rock
– Pioneer species- first species to populate
• Often lichens (fungus and algae)
– When they die they add organic material to become soil.
• Secondary succession – a disturbance changes an existing
community without removing soil.
– Land clearing and farming
– Wildfires
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Chapter 5.1 to 5.2:
Populations
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Three important characteristics
of a population
• 1. Geographic Distribution/Range
– Area inhabited by a population
– Varies in size- Microscopic to miles
• 2. Population Density
– Number of individuals per unit area.
– Can again vary greatly
• 3. Population Growth Rate
– A. Number of Births
– B. Number of Deaths
– C. Number of individuals who have entered/leave
population = immigration and emigration
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Types of Population Growth
• Exponential Growth– Under ideal conditions with unlimited resources.
– Will start out slow and then approaches an infinitely large
size - J curve
– Reproduce at a constant rate - Not in natural populations!
• Logistic Growth
– Populations growth will slow or stop after a period of
exponential growth
– As resources become less available, the growth of a
population slows or stops - S curve
– Reached carrying capacity- number of individuals that a
given environment can support
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Limits to Growth
• Limiting factors cause population growth to
decrease.
– Density Dependent- only become limiting when a
population reaches a certain level (TOO LARGE)
•
•
•
•
Competition
Predation
Parasitism
Disease
– Density Independent- affects populations in same
way regardless of size
• Unusual weather, natural disasters, seasonal cycles,
human activities
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Chapter 6.2 to 6.4:
Humans in the Biosphere
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Classifying Resources
• Renewable resources- can regenerate or can be replenished by
biochemical cycles
– Can be living or nonliving
• Nonrenewable resource- cannot be replenished by natural
process.
– Fossil fuels: coal, oil, natural gas.
• Classification depends on context
– EX: Trees
• Single vs. entire population
• Sustainable development
– Using natural resources without depleting them.
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Different types of Resources
• Land Resources
– Soil erosion- wearing away of soil by wind and water
– Desertification-turning once productive areas into deserts.
• Forest Resources
– Deforestation- loss of forests
• Fishery Resources
– Overfishing
– Aquaculture- raising aquatic animals for human consumption
• Air Resources
– Smog, pollutant
• Freshwater Resources
– Pollution
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Biodiversity: Greatest Natural
Resource
• Sum total of all the genetically based variety of
all organisms in the biosphere
– Ecosystem Diversity
• Habitats, communities, ecological processed
– Species Diversity
• Number of different species in the biosphere
– Genetic Diversity
• Sum total of all the genetic information carried by all
organisms living on earth today.
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Threats to Biodiversity
• Extinction- species disappears
• Endangered species- population size declining
• 1. Habitat Alteration
– Habitat fragmentation- development splits ecosystems into
pieces
• 2. Demand for wildlife products
• 3. Pollution
– Biological Magnification- concentration of harmful
substances increases at higher trophic levels
• 4. Introduced species
– Invasive species- reproduce rapidly because of lack of
predators
• Conservation efforts are in place to manage natural resources.
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Biological Magnification
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Charting the course for the
future
• Researchers are gathering data to study the
effects of human activities on the biosphere.
• Ozone depletion.
– Ozone layer- 20-50 kilometers above earth
surface. Absorbs UV light before it reaches
earths surface.
• Global climate change
– Global warming- increase in average
temperature of biosphere.
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