Ecology is the study of relationships between organisms and their environment. It is organized into levels from smallest (organism) to largest (biosphere). Energy flows through ecosystems via food chains and webs from producers to various consumer trophic levels. Matter recycles through biogeochemical cycles like carbon, nitrogen, phosphorus and water. Populations grow according to exponential or logistic models depending on resources and limiting factors. Communities involve interactions like competition, predation, and symbiosis that structure species niches.

1. Ecology
Nature’s Relationship Status

2. Ecology is the study of relationships among living organisms, between
different species of living organisms, and their environment. The word
ecology comes from the Greek words:
oikos meaning house
logos meaning the study of

3. With what theme of biology does ecology deal?
Interdependence in Nature

5. Ecology is organized into levels that reflect size and complexity. From
the first and smallest to the largest:
1. Organism: An individual; example….single fish
2. Population: Organisms of the same species that occupy the same
geographic area and use the same resources; example….school of fish
3. Biological Community: A group of interacting populations;
example….the school of fish, other animal species, and the plant-life in
the area
4. Ecosystem: A biological community and all of the abiotic factors
that affect it; example….coral reef
5. Biome: A large group of ecosystems that share the same climate
and have similar communities; example….the marine biome
6. Biosphere: Anywhere on Earth to include the atmosphere that life
exists.
NOW LET’S STUDY EACH LEVEL A BIT MORE FROM THE LARGEST TO
THE SMALLEST!

6. Life on earth extends from the ocean depths to 8 kilometers above the
earth's surface. Within this thin and fragile space called the Biosphere,
all of life's struggles for survival take place. The biosphere is an
extremely complex system; ecologists divide it into smaller, more easily
studied units. Remember from taxonomy, humans prefer organized
study.

7. This is a schematic to show
The various Biomes of the
biosphere. Study the
diagram, and make 5
observations of the
patterns you see
at work. Record
them in your
notes.
What do you think is
creating the
patterns
that you
see
?

8. An Ecosystem is a physically distinct, self-supporting unit of
interacting organisms and their surrounding environment. A tropical
rainforest, for example is an ecosystem. Its physical boundaries are the
areas where the trees give way to other types of vegetation.

9. A forest ecosystem is considered self-supporting because plants
convert energy from the sun into chemical energy. Forest animals then
eat the plants and in turn, are eaten by other animals, thus transferring
energy from one organism to another. When forest plants and animals
die, their bodies are decomposed by microorganisms, and the
chemicals released by this decomposition are then reused by other
living things.

10. By these four processes:
• production of chemical energy from sunlight
• transfer of energy from one organism to another
• decomposition of dead organisms
• reuse of nutrients by other living organisms
An ecosystem like the forest sustains itself year after year.

11. An ecosystem consists of two sets of environmental factors.
• Biotic factors are all the living organisms. An ecosystem contains
many different populations of species of organisms. Some are
easily seen, such as a squirrel or a maple tree and some are not
visible without a microscope, such as bacteria and protista.
• Abiotic factors are the nonliving parts of the ecosystem. These
factors include light, temperature, water, wind, soil.

12. Climate’s Effect On Ecosystems:
Climate: The average weather conditions in an area to include
temperature and precipitation. Factors that control climate:
1. Solar energy + the tilt of the Earth= unequal distribution of heat
2. Transport of heat in the biosphere
a. Unequal heating of the Earth’s surface drives winds; hot up & cold
down
b. Unequal heating of the ocean’s surface drives ocean currents; hot
up & cold down
3. Coastal or Continental? Coastal climates tend
to be more temperate because of water’s high
specific heat. Specific heat is waters tendency to
gain and lose heat SLOWLY. (remember H2O lab)
4. Precipitation: How much rain, sleet, snow?

13. • Tropical Zone: Near the equator (23.5⁰ N to 23.5⁰ S) Direct sunlight
year-round; HOT.
• Polar Zones/Arctic Zone: Areas around the North & South Poles
(66.5⁰N to 90⁰N and 66.5⁰S to 90⁰S) Sunlight strikes @low angles;
COLD.
• Temperate Zones: B/T the tropics and polar zones; affected by the
changing angle of the sun’s rays throughout the year; HOT & COLD
depending on the season.

14. Study this
diagram
& look for
patterns.
What do
you see?

15. Let’s examine the patterns seen in the diagram on the previous slide:
1. As moist, warm air rises over the equator and moves up in the atmosphere, it
cools.
2. The now cool air cannot hold as much water vapor as warm air and as it
condenses and rains…. A LOT creating tropical rainforest
3. Now the cool dry air falls, and as it gets closer to earth, it warms.
4. Warm air can hold a lot of water, so it sucks up all the water around 30 degrees
latitude North & South
5. This creates desert biomes. Go back a slide and check out the pattern.
6. Now this warm air that is full of water it sucked out of the desert, rises.
7. As it rises, it cools.
8. Cool air cannot hold as much water vapor as warm air and as it condenses and
rains….a moderate amount.
9. This allows for the temperate forests—not as lush as the tropical rainforests
because they have less rain and cooler temperatures.
10.Again the cool, dry air falls to earth and creates the polar “deserts”.
This warm moist air rising and cool dry air falling pattern repeats as you move up in
latitude creating the various biomes of the biosphere.

17. Study this
diagram
& look for
patterns.
What do
you see?

18. Energy Flows Through an Ecosystem
Every organism has one or two functional roles in the ecosystem
depending on whether they are autotrophs (producing food) or
heterotrophs (consuming food others have made).
• Plants and other photosynthetic organisms are autotrophs,
commonly known as producers. This is because they use the sun's
energy to produce their own food.
• Consumers, which are all heterotrophs, fall into categories based
on their feeding strategies. The main groups consist of:
1. Primary consumers/herbivores because they consume the
primary producers, which are mainly plants, and chlorophyll
containing bacteria.
2. Carnivores that eat flesh or meat.
3. Omnivores are not specialized and eat both plants and
animals.

19. • When organisms die what happens to their bodies?
Decomposition. Decomposers are organisms that feed off dead
and decaying matter called detritus. Decomposers help to make
healthy soil by returning the nutrients and chemicals. They play an
important role in recycling nutrients/matter such as Carbon,
Nitrogen, and Phosphorus back into the environment for producers
to reuse in the interdependent cycle of life.
Please click Simba below and belt out your best rendition of the Circle
of Life. Kinda want a video of this on GC! 

20. • Trophic Levels
A Trophic level is a position in a food chain. Trophic Levels are numbered
according to how far up the chain organisms are from the primary producers
at level 1 (plants, algae, some bacteria), to herbivores at level 2, to omnivores
and carnivores at level 3, 4, or 5.
o Primary Producers (organisms that make their own food from sunlight
and/or chemical energy from deep sea vents) are the base of every
food chain - these organisms are called autotrophs.
o Primary Consumers are animals that eat primary producers; they are
also called herbivores (plant-eaters).
o Secondary Consumers eat primary consumers. They are carnivores
(meat-eaters) and omnivores (animals that eat both animals and
plants).
o Tertiary Consumers eat secondary consumers.
o Quaternary Consumers eat tertiary consumers.
Food chains "end" with top predators, animals that have little or no natural
enemies. When any organism dies, it is eventually eaten by detrivores (like
vultures, worms and crabs) and broken down by decomposers (mostly
bacteria and fungi), and the exchange of energy continues.

21. If we take all the Food Chains that interact with one another in an
ecosystem and make diagram illustrating their connectedness you have
a Food Web. Arrow “points to the piehole” of the eater.

23. • Pyramid of Energy: 10% Rule: Only about 10% of the energy
available at one trophic level is transferred to organisms at the next
trophic level.
• Pyramid of Biomass: Biomass is the total amount of living tissue in a
trophic level.
• Pyramid of Numbers: Represents the number of individual
organisms at each trophic level.

24. Study this diagram and answer this question in your notes,
“Why are ecosystems Limited to only 5 trophic levels?”

25. Community Ecology:
• Community - A group of interacting populations that live in the same area
and use the same resources; this level of ecology focuses on interactions
b/t different populations.
• A species’ Niche is basically its ecological role, which is defined by the set
of conditions, resources, and interactions it needs to survive.
• Community interactions include:
1. Competition is the “fight” for resources in the environment
o Interspecific Competition – occurs between members of different
species LION/HYENA FOR FOOD
o Intraspecific Competition – occurs among members of the same
species MALES WILL COMPETE FOR MATES OR TOP PLACE IN PACK
o Competitive Exclusion Principle: States that two species cannot
coexist if they occupy the same ecological niche (competing for
identical resources).
o Two species whose niches overlap may micro-evolve by natural
selection to have more distinct niches, resulting in Resource
Partitioning.

27. A famous example of the competitive exclusion principle is
shown below, in which two types of single-celled
microorganisms
1. Paramecium aurelia
2. Paramecium caudatum
were grown separately in the lab(Tubes A & B), & both species
thrive. But when they are grown in the same habitat (Tube C)
with a fixed amount of nutrients, both grow more poorly and P.
aurelia eventually outcompetes P. caudatum for food, leading
to the extinction of P. caudatum.
Test Tube A Test Tube B
Test Tube C

28. 2. Predation—Species A hunts and is a predator of Species B.
Predator – is the animal that hunts
Prey – is the animal that is hunted
3. Herbivory—Herbivore(a rabbit) eats plants(clover)
4. Symbiosis– An arrangement where two species live/interact
together in some fashion
o Mutualism ( +/+ ) is a relationship in which both species benefit;
ex. bees & flowers
o Parasitism ( +/- ) is a relationship in which one species benefits &
the other is harmed; ex. athlete's foot— a fungus that “eats” the
skin of feet
o Commensalism ( +/ 0 ) is a relationship in which one species
benefits & the other is neither helped nor harmed; ex. Cattle egret
and cattle

29. Symbiotic
relationships

30. Population Ecology—All the organisms of the same species in a given
area. Three important characteristics of populations are geographic
distribution, density, and growth rate.
1. Geographic Distribution – the range or area inhabited by the
organism.
2. Population Density – the number of individuals per unit area
3. Growth Rate– how the numbers in the population go up and go
down. Growth rate can be calculated with the following formula:
𝒏𝒖𝒎𝒃𝒆𝒓 𝒐𝒇 𝒃𝒊𝒓𝒕𝒉𝒔+𝒊𝒎𝒎𝒊𝒈𝒓𝒂𝒕𝒊𝒐𝒏 −(𝒏𝒖𝒎𝒃𝒆𝒓 𝒐𝒇 𝒅𝒆𝒂𝒕𝒉𝒔+𝒆𝒎𝒊𝒈𝒓𝒂𝒕𝒊𝒐𝒏)
𝑻𝒊𝒎𝒆

31. Two types of growth:
1) Exponential Growth
o Rapid growth
o Which forms a j-shaped growth curve
o Starts slowly due to the lag time required for sexual maturity
o Occurs under ideal conditions with unlimited resources
2) Logistic Growth
o Initial rapid growth rate
o Then the growth slows and reaches a level of stability
o Starts like exponential growth but then resources become limited
o Reaches carrying capacity(K) which is the maximum population an
ecosystem can support.

32. • LIMITING FACTORS - Factors that limit the survival, distribution, or reproduction of
organisms thus regulating the size of the population.
1. DENSITY DEPENDENT Factors
o competition, predation, parasitism, and disease
o numbers matter!
2. DENSITY INDEPENDENT Factors
o weather, natural disasters, human activities
o numbers do not matter!

33. Matter Recycles:
While energy is crucial to an ecosystem, all organisms ALSO require
matter and nutrients. While energy is supplied from a steady flow
from the sun, matter is recycled in the biosphere and is used over
and over again.
Matter circulates in the biosphere through the Biogeochemical
Cycles:
BIO: LIFE GEO: EARTH CHEMICAL:
MATTER

34. The Water Cycle
• Water changes from liquid to gas (water vapor) due to sun’s heat by Evaporation
& Transpiration (evaporation through the stomata of plant leaves).
• The moist air heats and rises. As it rises, the air cools and the water vapor
condenses into tiny droplets which become clouds, this is called Condensation.
• As the droplets enlarge, they fall as rain, sleet, or snow. This is called
Precipitation.
• Water collects and runs downhill, Runoff, toward streams and rivers and
eventually finds its way into larger bodies of water.
• Some water seeps into the ground and is absorbed through the plant roots where
is is used to
supply ____ for
photosynthesis.
You fill in the
blank!

35. The Carbon Cycle
• Carbon is a key ingredient to all living things. It is like the pasta of the
Italian meal. It is found in all parts of the Earth: the ocean, rocks,
and the atmosphere.
• Carbon cycles through the Earth in 4 basic ways:
1. Heterotrophs ingest (eat) food and exhale CO2 as a waste product;
autotrophs “inhale” that CO2 and use the carbon to produce sugar
(fruits & veggies)….C6H12O6
2. Volcanos release large amounts of CO2 into the atmosphere.
3. Dead organisms that are buried are converted into fossil fuels by
heat, pressure& time. Fossil fuels are compressed stores of large
quantities of carbon and energy.
4. Human activity burning fossil fuels release CO2 into the atmosphere.

37. The Nitrogen Cycle
• Nitrogen is an essential ingredient in proteins.
• Most of the Earth’s nitrogen is in the atmosphere in gas form.
• Bacteria are the only organisms that can us gaseous nitrogen. They
can convert nitrogen gas into ammonium. This process is called
Nitrogen Fixation.
• Plants absorb the ammonium and use the nitrogen to produce
proteins.
• Other Nitrifying Bacteria take some of the ammonium and convert it
to nitrates which are also used by the plants as a source of nitrogen
for amino acids.
• Heterotrophs eat the producers or other consumers lower in the
food chain and reuse the nitrogen to make their own proteins.
• As organisms die, Decomposers return the nitrogen back to the soil
in the form of ammonia.
• Finally, still other soil bacteria convert ammonia back to gaseous
nitrogen in a process called Denitrification.

39. The Phosphorus Cycle
• Phosphorus is a main ingredient in DNA
• Phosphorus is found in rocks and soil.
• Plants absorb the phosphorus from the soil and use it to make their
own DNA.
• Heterotrophs then get phosphorus by eating plants.
• As water flows over rocks it picks up phosphorus and delivers it to
the ocean where marine producers incorporate it in their own DNA.
• Decomposers return phosphorus back to the soil.
The Oxygen Cycle
• The picture tells it all and
you learned this in DETAIL
during bioenergetics.