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ecology
a look at the basics
Ecology – The study of the
interactions of the living and
non-living world.
Ecology terms/groupings
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Species—one kind of organism; similar in
structure and able to pass these traits on to
offspring.
Population—all the members of a species
living in a given geographic area.
Community—all of the populations in an
area; i.e., all of the living things.
Ecology terms/groupings
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Ecosystem—the interaction of the community
with the non-living environment
Biome—a group of ecosystems that have the
same climate & similar biological
communities; ex.—grassland, desert, wetland,
tropical rainforest, &c.
Biosphere—all the parts of the planet in
which life exists.
www.eoearth.org
biosphere
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Dynamic!!
Extends from about
6 mi below surface
to 5 mi above
(discontinuous)
About 0.0007% of
the Earth by volume
About 0.00008% of
the Earth by mass
the biosphere
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https://montagepages.fuselabs.com
= peel
Unique
Ecosystems
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Biotic factors – the living part of
the ecosystem.
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Geese
Plankton
People
Trees
Fungi
bacteria
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Ecosystems
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Abiotic factors – the
non living parts of the
ecosystem.
Air
 Sand
 Water
 Temperature
 Wind
 Sunlight
 pollutants
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Ecology
 The
main point is how
energy moves through the
ecosystem.
Energy in Ecosystems
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Energy from the Sun is
the major source for all
living things.
The process of
photosynthesis traps it so
it can be used by living
organisms.
Energy is NOT recycled
throughout the
ecosystem
Ecology
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Organisms can be producers or consumers
Producers (autotrophs)—convert energy
from the environment into carbon bonds
such as those found in glucose
chemicals
Plants
Algae
Cyanobacteria
Deep sea bacteria
photosynthesis
chemosynthesis
Electromagnetic spectrum
http://www.antonine-education.co.uk/physics_gcse/Unit_1/Topic_5/topic_5_what_are_the_uses_and_ha.htm
Pigment absorption across the
visible spectrum
PHOTOSYNTHESIS
sunlight
Carbon
dioxide
glucose
water
Sunlight + 6 CO2 + H2O
oxygen
C6H12O6 + 6 O2
photosynthesis
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Sunlight energy used to form C-C bonds in
the form of sugar (glucose)
The sugars can be used or can be converted
to cellulose, starch, or other substances
CHEMOSYNTHESIS
So…why are producers
important?
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Ecology is all about energy flow
LIFE is all about energy flow
Our source of energy is…
Producers are…
Consumers = heterotrophs
Get their energy from the carbon bonds made
by producers…
4 types:
Consumer
Trophic level
Food source(s)
Herbivores
Primary
Plants
Carnivores
Secondary or higher
Animals
Omnivores
All levels
Plants, animals, and
others
Detritivores
------------------
detritus
Consumers
 Some
animals do not
specialize in their diets
(called generalists)… they
feed on several trophic
levels.
Consumers
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Most species are much more specific in
their diets—these are called specialists.
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Which one are we???
Energy flow
sun
HEAT
HEAT
producers
consumers
Inorganic
nutrients
decomposers
HEAT
Energy flow
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Energy flows in the form of carboncarbon bonds (in organic molecules)
Bonds = energy
1 glucose molecule = 686 kcal
1 ATP = 7.3 kcal
1 glucose  36 ATP
So…38% of energy from glucose
yields ATPs—62% lost as heat
Energy flow
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Photosynthesis = C-C bonds formed (glucose)
from sunlight (energy), water and CO2
Respiration = C-C bonds broken to form CO2
& energy
ATP (used)
heat (lost)
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All energy is, ultimately, lost—10% rule
Food Chain
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Series of steps in an ecosystem in which organisms transfer energy by
eating and by being eaten.
Energy flows in one direction from sun or inorganic compounds to
autotrophs to various heterotrophs
Food Chain
Arrows show the direction the energy is flowing.
Food Webs
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Many food chains combined together.
Hognose Snake
Rabbit
Toad
Hawk
Mouse
Spider
Grasshopper
Grasses
Garter Snake
Preying Mantis
Sparrow
This is a grazing food web.
Producers are at the base of this type
of food web.
www.stephsnature.com
Food webs
Food Webs
A detrital food web.
Detritus is the dead stuff
that falls to the ground or
substrate and feeds
myriad critters.
Decomposers are at the
base of this type of food
web.
http://www.econguru.com/fundamentals_of_ecology/ecosystems.html
Food Webs
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So…what’s wrong with food webs???
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Focus on static structure
Reliance on stability or persistence of species
Poor model for analyzing more dynamic
situations
Do not fully account for all species and links
present
Ignore spatial and temporal variability
Spatial variability
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Differences in the food web depending
upon location in the ecosystem
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Vertically
Horizontally (2D)
Temporal variability
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Differences in the food web depending
upon time
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Time of day
Time of year
crepuscular
diurnal
nocturnal
Temperate
 Tropical
 Migrations
 Life cycles/stages
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summer
winter
wet
dry
Life cycles
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Young and adults have different diets
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Tadpole vs frog
Caterpillar vs. butterfly/moth
Grub vs beetle
Mosquito larvae vs. adults
Etc.
Prevents competition for same resources
ecosystems
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Rivet analogy
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Redundancy in the system
Niche
Microhabitats
There are about 1.5 million rivets in a Boeing
737…how many would you remove (if you
were flying in it)???
ecosystems
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Common metaphor
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Stone arch
Loading forces = interactions
among species
Keystone speciesholds it all up
=stability (static)
ecosystems
•Dynamic in space and time
•Members of the system
(species/populations)
•Adapt
•Change strategies
•Like a sports team
ecosystems
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A better metaphor is Jenga (Jenga hypothesis)
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Governed by simple rules of balance & energetics
Constantly changing—additions & deletions of parts
Stability at any moment depends on the importance of
a given ingoing or outgoing piece’s contribution to the
structure
Open and flexible
Change species attributes, composition, and dynamics
Ecological Pyramid
Ecological Pyramid
http://www.metrolic.com/travel-guides-the-great-pyramid-of-giza-147358/
Ecological Pyramid
Uhhhh…wrong pyramid…
Ecological Pyramid
That’s more like it!!!
Ecological Pyramid
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Is a diagram that shows the relative
amounts of energy or matter contained
within each trophic level in a food chain or
food web.
3 types:
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biomass,
energy, or
numbers
What is a trophic level?
Ecological (biotic) pyramids
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As written by Aldo Leopold,
“The species of a layer are
alike not in where they came
from, or in what they look like,
but rather in what they eat.”
Trophic levels
First level =
Second level =
Third level =
Fourth level =
Biomass Pyramid
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The total mass of living tissue at each trophic level.
Represents the amount of potential food available for each trophic level in
an ecosystem
Biomass Pyramid
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The first level includes producers.
Here we find the most abundant amount of
biomass.
Biomass Pyramid
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Generally, the further removed a trophic
level is from its source (detritus or
producer), the less biomass it will contain.
WHY?
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Not everything in the lower levels gets eaten
Not everything that is eaten is digested
Energy is always being lost as heat
Biomass Pyramid
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A few exceptions…
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Aquatic ecosystems
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Algae outnumbered & outweighed by critters that
eat them
How does it work, then??????????
Algae can reproduce at least as quickly as they are
eaten
 Algae are mostly digestible (much more so than
terrestrial plants)
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Energy Pyramid
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About 10% of the
total energy is
transferred to this
level to be used by
these consumers.
This is the 10% Rule
10 cal
100 cal
1000 cal
10,000 calories
Ecological pyramids
Numbers pyramid
Pyramid of numbers
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The number of organisms at each trophic level.
Biogeochemical Cycles
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Elements, Chemical compounds and other
forms of matter are passed from one
organism to another and from one part of
the biosphere to another.
Pass the same molecules around again and
again within the biosphere.
Matter is always recycled!
Water Cycle
Carbon cycle
Nitrogen Cycle
Phosphorus Cycle
geology.usgs.gov
Nutrient cycling
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Ecosystems can be sources, sinks, or
transformers of chemicals
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Source = supplier of nutrients to other
habitats
Sink = “holder” of nutrients from other
habitats
Transformer = takes nutrients in one form
and gives them up as another form
NICHE
All the roles that an organism plays in its
environment.
what it eats
physical changes to habitat
what eats it
symbionts
parasites
what it takes from the habitat
what it puts into the habitat
Some Ecological Roles
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Prey
Predator
Symbiosis
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Commensalism
Mutualism
Parasitism
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