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ECOLOGY
CHAPTERS 13, 14, AND 15
13-1 WHAT IS ECOLOGY?

Interactions and Interdependence

Ecology is the scientific study of interactions among
organisms and between organisms and their environment.
13-1 WHAT IS ECOLOGY?

Levels of Organization
13-1 WHAT IS ECOLOGY?

Levels of Organization

Species
group of organisms so similar to one another that they can breed
and produce fertile offspring.
 Example: human beings


Population
groups of individuals that belong to the same species and live in
the same area.
 Example: Clements High School faculty, students, and staff


Community
different populations that live together in a defined area.
 Example: CHS faculty, students, and staff AND the roaches that
live here too!

13-1 WHAT IS ECOLOGY?

Levels of Organization

Ecosystem
collection of all the organisms that live in a particular place,
together with their nonliving, or physical environment
 Example: CHS faculty, students, staff and roaches…as well as the
building itself, water fountains, desks, etc.


Biome
group of ecosystems that have the same climate and similar
dominant communities
 Examples: tropical rain forest, tundra, desert


Biosphere

contains the combined portions of the planet in which all of life
exists, including: land, water, and atmosphere
13-1 WHAT IS ECOLOGY?

Levels of Organization
Biosphere
Biome
Ecosystem
Community
Population
Individual
13-1 WHAT IS ECOLOGY?

Modern Ecological Research

Observing


first step in asking ecological questions
Experimenting
Used to test hypotheses
 May set up an artificial environment in a laboratory to imitate and
manipulate conditions that organisms would encounter in the wild.
 Others are conducted within natural ecosystems


Modeling
Gain insight into complex phenomena
 Many consist of mathematical formulas based on data collected
through observation and experimentation
 Predictions made are often tested by further observations and
experiments

13-3 ENERGY IN ECOSYSTEMS

Where does energy come from?
THE SUN! {Main energy source for all life on earth}
 Chemicals


Autotrophs

Auto=self; troph=feeding

Organisms that use energy from the environment to
build large organic molecules needed for life
(carbohydrates, proteins, lipids, and nucleic acids)
AKA: producers
Photosynthesis




using light energy to convert CO2 and H2O into O2 and
carbohydrates
Chemosynthesis

using chemical energy to produce carbohydrates
13-3 ENERGY IN ECOSYSTEMS
13-3 ENERGY IN ECOSYSTEMS

Heterotrophs
Hetero=other; troph=feeding
 Cannot harness energy directly from the physical
environment
 Rely on other organisms for their energy and food supply
 AKA: consumers

13-3 ENERGY IN ECOSYSTEMS

Heterotrophs





Herbivores – eat plants
Carnivores – eat animals
Omnivores – eat both plants and animals
Detritivores – feed on plant and animal remains, dead
matter
Decomposers – break down/recycle organic matter
13-4 FOOD CHAINS AND FOOD WEBS

Direction of Energy Flow
Flows through an ecosystem in ONE direction, from the sun
or inorganic compounds to autotrophs and then to various
heterotrophs
 Energy stored by producers can be passed through an
ecosystem along a food chain.

Series of steps in which organisms transfer energy by eating and
being eaten
 The arrow points to where the food is going {toward the MOUTH!}

Small Fish
Zooplankton
Squid
Algae
Shark
13-4 FOOD CHAINS AND FOOD WEBS

Direction of Energy Flow

Food Web
Most feeding relationships are more complex than a food chain.
 Food webs link together all the food chains in an ecosystem.

13-4 FOOD CHAINS AND FOOD WEBS

Direction of Energy Flow

Food Web
13-4 FOOD CHAINS AND FOOD WEBS

Trophic Levels

Each step in a food chain or web
Producers – 1st trophic level
 Consumers – 2nd, 3rd, 4th, etc. trophic levels


Only 10% of the energy available within one trophic level is
transferred to organisms at the next trophic level- 90% is
lost
13-5 CYCLING OF MATTER

REFER TO YOUR CYCLES BOOKLET!
13-6 PYRAMID MODELS

Ecological Pyramids
Shows the relative amounts of energy or matter contained
within each trophic level in a food chain or food web.
 Energy Pyramid


Relative amount of energy available at each trophic level.
0.1% Third-level
consumers
1% Second-level
consumers
10% First-level
consumers
100% Producers
13-6 PYRAMID MODELS

Ecological Pyramids

Biomass Pyramid
Represents the amount of living organic matter at each trophic
level.
 Typically, the greatest biomass is at the base of the pyramid.

13-6 PYRAMID MODELS

Ecological Pyramids

Pyramid of Numbers

Shows the relative number of individual organisms at each trophic
level.
13-2 BIOTIC AND ABIOTIC FACTORS

Biotic


Abiotic


Living things – plants, animals, protists, fungi, bacteria
Nonliving things – temperature, wind, sunlight, rainfall, soil
Biodiversity

The variety of living things in an ecosystem
14-1 HABITAT AND NICHE

Habitat


The area where an organism lives is called its habitat. A
habitat includes both biotic and abiotic factors.
Niche
full range of physical and biological conditions in which an
organism lives and the way in which the organism uses
those conditions- Role of the organism
 No two species can share the same niche in the same
habitat.

14-2 COMMUNITY INTERACTIONS

Ecological Relationships

Competition
Occurs when organisms attempt to use an ecological resource in
the same place at the same time
 Examples of resources: water, nutrients, light, food, or space.
 Direct competition in nature often results in a winner and a loser—
with the losing organism failing to survive.
 The competitive exclusion principle states that no two species can
occupy the same niche in the same habitat at the same time.

14-2 COMMUNITY INTERACTIONS

Ecological Relationships

Predation
One organism captures and feeds on another organism
 The organism that does the killing and eating is called the predator,
and the food organism is the prey.

14-2 COMMUNITY INTERACTIONS

Ecological Relationships

Symbiosis
Two species live closely together
 Symbiotic relationships include:
 Mutualism: both species benefit from the relationship
 Commensalism: one member of the association benefits and
the other is neither helped nor harmed
 Parasitism: one organism lives on or inside another organism
and harms it.

14-3 AND 14-4 POPULATION GROWTH

Carrying Capacity
Maximum number of individuals of a particular species that
the environment can normally support
 Can change when the environment changes

14-3 AND 14-4 POPULATION GROWTH

Population Crash


Dramatic decline in the size of a population over a short
period of time
Factors that limit population growth

Density Dependent
Affected by the number of individuals in a given area
 Competition, predation, parasitism, disease


Density Independent
Limit a population’s growth regardless of the population’s density
 Natural disasters, human activity

14-5 ECOLOGICAL SUCCESSION

Ecological Succession
Series of predictable changes that occurs in a community
over time
 Sometimes, an ecosystem changes in response to an
abrupt disturbance.
 At other times, change occurs as a more gradual response
to natural fluctuations in the environment.
 Primary Succession

On land, occurs on surfaces where no soil exists
 Example: rock surfaces formed after volcanoes erupt
 The first species to populate the area are called pioneer species.


Secondary Succession
Changed by natural events, such as fires
 Community interactions tend to restore the ecosystem to its original
condition through secondary succession.

4-1 THE ROLE OF CLIMATE

What is Climate?
Weather is the day-to-day condition of Earth's atmosphere
at a particular time and place.
 Climate refers to the average year-after-year conditions of
temperature and precipitation in a particular region.


Caused by:
 Trapping of heat by the atmosphere
 Latitude
 Transport of heat by winds and ocean currents
 Amount of precipitation
 Shape and elevation of landmasses
4-1 THE ROLE OF CLIMATE

Greenhouse Effect

Atmospheric gases that trap the heat energy of sunlight and
maintain Earth's temperature range include:
carbon dioxide
 methane
 water vapor

Sunlight
Some heat
escapes
into space
The natural situation in which
heat is retained in Earth’s
Atmosphere by this layer of gases

Greenhouse
gases trap
some heat
Atmosphere
Earth’s Surface
4-1 THE ROLE OF CLIMATE

Latitude

Solar radiation strikes different parts of Earth’s surface at an
angle that varies throughout the year.
Equator - energy from the sun strikes Earth almost directly.
 North and South Poles - the sun’s rays strike Earth’s surface at a
lower angle.


3 Main Climate Zones

polar, temperate, and tropical
4-1 THE ROLE OF CLIMATE

3 Main Climate Zones

polar, temperate, and tropical
Sunlight
90°N North Pole
Arctic Circle
Sunlight
Most direct sunlight
Polar
66.5°N
Temperate
Tropic of Cancer
23.5°N
Equator
0°
Tropic of Capricorn
Tropical
23.5°S
Sunlight
Temperate
Antarctic Circle
Sunlight
66.5°S
90°S South Pole
Polar
4-1 THE ROLE OF CLIMATE

Heat Transport in the Biosphere
Unequal heating of Earth’s surface drives winds and ocean
currents, which transport heat throughout the biosphere.

WINDS
66.5°N
Polar
Easterlies
Westerlies
Northeast Trade Winds
23.5°N
0° Equator
Southeast Trade Winds
Westerlies
23.5°S
66.5°S
Polar
Easterlies
Prevailing
winds
4-1 THE ROLE OF CLIMATE

Heat Transport in the Biosphere

Unequal heating of Earth’s surface drives winds and ocean
currents, which transport heat throughout the biosphere.
OCEAN CURRENTS
66.5°N
23.5°N
0°
Equator
23.5°S
66.5°S
Warm currents
Cold currents