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Ecology
Biology I
The Hierarchy of Life
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Atoms
Molecules
Macromolecules (proteins, lipids, carbs, nucleic acids)
Organelles
Population: a group of same
species all living together and
Cells
interacting (ex. A population of
Tissues
deer)
Organs
Community: all of the different
Organ systems
living things in the same area
that interact (plants, deer, foxes,
Organisms
racoons, etc.)
Populations
Ecosystem: all of the living and
Communities
non-living things in an area
Ecosystems
Biome – like ecosystems found
Biomes
throughout the world (desert,
bioshere
forest, grasslands, etc.)
Abiotic vs. Biotic
Factors
• Abiotic – non-living things
• Biotic – living things
Ecosystem Ecology
• The study of the flow of matter and energy
through ecosystems
– Food Webs
– Energy Pyramid
– Carbon, Nitrogen, & Water Cycles
Food Webs
Food Webs – show the
flow of Energy
• All energy enters the food web by the
producers (photosynthesis)
• Energy Flows through the food web and is
not recycled
• Matter is recycled by the decomposers
• Trophic Levels – feeding levels
Food Webs Continued
• Producers - synthesize organic molecules from
inorganic molecules and the sun’s energy
(produce about 170 billion tons or organic
material/year)
• Consumers – never more than 3-5 trophic levels
since the producers can only support so many
consumers
– Primary Consumers – eat producers
– Secondary Consumers – eat the primary consumers
– Tertiary Consumers – eat secondary consumers
• Decomposers – break dead things back down to
inorganic materials
Food Webs Continued
• Autotrophs – make own food (producers)
• Heterotrophs – must eat to get food
(consumers and decomposers)
• Herbivore – plant eater
• Carnivore – only eat animals
• Omnivore – eat either plants or animals
Energy Pyramid
• Maximum of 3-5 trophic levels
• 5-20% of energy is transferred to the next
trophic level – lose 80-90% of energy in the
transfer to the next level
• Why is Energy lost before getting to the next
level?
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Lost in CR (energy is used)
Energy is lost as heat
Energy is used to eat and get food
Lost in feces
Some of the molecules cannot be broken down and
used for energy (cellulose, bone, etc.)
Energy Pyramids
Cycles
Matter is recycled inorganic→organic→inorganic
Cycles between:
• Soil – abiotic reservoir for elements
• Air – abiotic reservior for elements
• Rocks – unusable abiotic reservoir, can
be used after erosion
• Living Organisms – reservoir for organic
matter
Water Cycle
Water Cycle
• Precipitation going into the soil of bodies
of water is how water enters the food web
• It leaves the living things by transpiration
and cellular respiration and evaporation
from the bodies of water to go back into
the air
Carbon Cycle
Carbon Cycle
• Carbon enters the food web from the air
thru photosynthesis
• Passed thru food web by eating
• Returned to the air by cellular respiration,
decomposition, and combustion
Nitrogen Cycle
Nitrogen Cycle
• Nitrogen makes up most of the air but it is
unusable since it is N2 and almost no living
things have enzymes that can break that bond
• Special Nitrogen fixing bacteria can turn N2 in
the air into useable nitrogen that can be sucked
up by plants and used to convert sugars to aa
and nucleotides
• Decomposition of dead things and feces and
urine also puts nitrogen into the soil
• Nitrogen enters the air by denitrifying bacteria
Nitrogen Cycle
Human Impact on
Cycle
• Acid rain is carried by the wind
• Moving nutrients or removing them all together
• Fertilizer can cause eutrophication of lakes (too
much nutrients lead to too many photosynthetic
organisms – clog lake)
• Introduce toxins into the enviroment
(biomagnification)
• Ozone depletion
• Urbanization
• Introduction of exotic species
• Genetically engineering plants to resist
herbicide and weeds, fish engineered to resist
cold temps.
Community Ecology
• The study of interactions and
relationships among the organisms in
an ecosystem (why are certain
species found together, how do they
adapt to one another?)
Community Ecology
Relationships
1. Symbiosis – close relationships where
the organisms are interdependent
– Mutualism – good for both (pollination, E-Coli
in intestine, nitrogen fixing bacteria and
plants, etc.)
– Commensalism – good for one, doesn’t help
or hurt the other (barnacles on whales)
– Parasitism – good for one, hurts the other
• Endo – tapeworms
• Ecto – ticks, leeches
Mutualism
Commensalism
Parasitism
Relationships
Continued
2.Predator/Prey – causes both behavioral
and evolutionary adaptations
Prey
• Behavioral Adaptations – learn to hide, warn each other
• Evolutionary Adaptations – make prey better at avoiding
being found, captured, or consumed – selected for over
many generations!
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Warning colors
Mimicry
Camoflage
Defensive postures
speed
Predator/Prey
Relationships Continued
Predator
• Evolutionary Adaptations – makes the predator
better at finding, capturing, and eating prey
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Teeth
Camoflage
Speed
Heated pits
Lateral lines
Spider webs
Population Cycles
Amt. of prey controls
amount of predator and vice
versa
•as rabbits go up – lag and
then predators increase
because get more to eat more energy to reproduce
•too many predators – eat
too much prey – predators
start to die off because not
enough food
•Less predators, more prey
survives - #’s increase etc.
etc.
3. Plant/Herbivore
Interactions –
Relationships Continued
• Evolutionary – plants develop defenses
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Prickles
Thorns
Tough leaves
Stick hairs
Toxic chemicals (nicotine, strychnine, etc.)
Co-Evolution – plant better defends, herbivore
overcomes defense, plant develops new defense,
etc. etc.
4. Competition – Still
Relationships
• Several species competing for homes, food
• Usually this is not really a relationship because it causes
behavioral and evolutionary adaptations that eliminate
the competition
• Behavior Adaptation – niche switching – animals
change niches (roles) so no longer competing – ex.
Birds competing for homes in a tree – some live high in
the tree, other species lives lower
• Evolutionary Adaptations (slow gradual change over
time to organisms best suited – competition dies off)
– Ex. Plants that release toxins in soil that kill surrounding plants
like mesquite in the desert
– Ex. Characteristics that allow them to get food better – finches
beak
– Killer bee queen killing other queens at birth so there will only
be killer bees.
Succession
• Succession – a slow gradual change in a
community over time – not evolutionary
adaptations to environment – due to the # and
type of organisms that live in an area based on
things moving in and others dying out
• When some plants move in they make it more
hospitable to other plants enabling them to
move in and they choke off the plants that were
originally there
Succession Continued
• Primary Succession – on land that
previously contained no life – ex. New
islands, rock, area of a retreating glacier
• Secondary Succession – replacement of
species after a major disruption (fire,
flood, volcano, tsunami, over grazing
• In both the land is colonized by species
which are gradually replaced
Succession Continued
1. Pioneer Plants (weeds, herbs, tiny shrubs,
moss, lichens
Good at colonizing – small, fast growing,
fast reproducing, good seed dispersal
2. Grasses – trap soil and moisture making it
better for trees to grow
3. Trees – usually more competitive and will
eventually take over – shade out smaller
plants
Climax Community – stable community –
succession has stopped – no more species
can fit
Succession – gradual change
in species over time due to
new things moving in
Population Ecology
• The study of what affects the numbers and
make-up of organisms in a population
• Factors that affect population growth
– Competition within species for same resources –
more organisms, decrease in food and survival
– Predation (more deaths as population increases)
– Build up of toxins
– Stress (high density induces stress and makes
hormonal changes to animals, reproduce less and
die quicker
– Climate
– Natural Disasters
– Disease
Population Ecology
Continued
• Population cycles – populations vary with
regularity caused by:
– Stress due to overcrowding – population gets
too big and then declines
– Inability to find food, homes, shelter, etc.
when population gets large
– Build up of toxins in a large population
– Build up of prey, followed by a build up of
predators which eat more prey making them
decrease, which causes death of predators
since they don’t have enough food
Organismal Biology
• Study of how organisms are adapted to
their environment
• Abiotic Factors determine what things can
live in an area
• Types of Adaptations:
– Behavioral (animals only) – migration, hiding
under a rock, burrowing into the ground
– Physiological (reversible) – takes minutes to
weeks – ex. Ability to constrict blood vessels
to respond to the cold, making more RBC’s
when go to high elevations that are lower in
oxygen
Organismal Ecology
Continued
• Morphological Adaptations – change form
or anatomy (grow fur, change coat color,
change leaf shape)
• Evolutionary Adaptations – cactus having
spiny leaves and super thick cuticles
Biomes – areas with
similar environments and
also similar living things
• Aquatic – oceans, freshwater, wetlands,
estuaries
• Terrestrial – tropical rainforest, temperate
rain forest, deciduous forest, coniferous
forest (taiga), temperate grassland,
tropical grasslands (Savanna), chaparral,
tundra, desert