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Introduction to Ecology
Understanding the World
• What affects the environment also affects you.
• Understanding what affects the environment is
important because it is where you live. (ie. Global
Warming)
What is Ecology?
• Ecology is the study of interactions that take
place between organisms and their environment
• These interactions determine the distribution of
organisms and their abundance
• Modern ecology includes observation and
experimentation
• Ecology covers the study of plants and animals,
including where they grow and live, what they
eat, or what eats them, is called natural history
Interdependence or
Interconnectedness
• All organisms interact
with other organisms in
their surroundings and
with the nonliving part of
their environment
• This survival depends on
their interdependence
which is the key term
found throughout
ecology
ANTS AND ACACIA: These ants actually harm acacia trees (Savannah
Africa)in the absence of large herbivores by allowing infestations by other
harmful insects, such as the parasitic scale bugs also pictured here.
Ecological Research
• Most ecologists use scientific research includes
using descriptive and quantitative methods
• They obtain descriptive information by observing
organisms
Levels of
Organization
1. Most inclusive level of
organization
2. Biosphere is the thin layer
of Earth & its atmosphere
that supports life
3. Extends high in the
atmosphere to bottom of
oceans
4. Supports a diverse group of
organisms in a wide range of
climates
5. All organisms are found
within the biosphere
The
Biosphere
Ecosystem
• The biosphere is made of smaller units called ecosystem
• Ecosystems include all of the organisms and the nonliving
environment
Non-living Factors
include:
pH, levels of dissolved
oxygen, carbon dioxide,
& sunlight
Communities
• A community is all the interacting organisms living in an area
Describes all the fish,
plants, algae, bacteria
and other living
organisms found in
this River Ecosystem
Population
• A population includes all the
members of a species that
live in one place at the same
time
• Members of the same
population may compete
with each other for food,
water, mates, or other
resources.
Represents a population of
California Poppies
Organism
• An organism is an individual living thing that is
made possesses all the characteristics of life
Ecosystem
Components
Biotic vs. Abiotic
• Ecologists separate the environmental factors that influence an
organism into two types
1. Biotic Factors-all living things that affect an organism
2. Abiotic Factors-non-living are the physical and chemical
characteristics of an environment
Abiotic Factors
• Abiotic factors include temperature, humidity, pH, salinity,
oxygen concentration, amounts of sunlight, availability of
nitrogen, and precipitation
• Are not constant; vary from place to place and over time
Also important are the small
Amounts of temperature differences
Within a habitat like under a
Shade tree
Organisms in a changed
environment
• Each organism is able to survive within a limited range of
environmental conditions
• Example: an organism may be able to function only within a
specific range of temperature. To determine the range, measure
how efficiently it performs at different temperatures
• A graph of performance vs. values of an environmental
variables ie: temperature is called Tolerance curve
Acclimation of organism
Some organisms can adjust their tolerance to abiotic factors
through the process of acclimation
Example: goldfish raised at different temperatures have somewhat
different tolerance curves
This occurs within the lifetime of an individual (different from
adaptation)
Environments change in:
• Temperature, light, moisture, salinity, and other chemical
factors
• There are 2 ways for organisms to deal with some of these
changes in their environment
• 1. Conformers: are organisms that do not
regulate their internal conditions; they change as
their external environment changes
• 2. Regulators: use energy to control some of
their internal conditions
Control of Internal Conditions
• Conformers change their
internal conditions to
what ever the external
environment is.
Conformers are Snakes
• Regulators maintain
their internal
conditions constant.
Such as as body
temperature, in
humans the normal
body temperature is
98.6
Escape from unsuitable
conditions
• Some species can survive unfavorable
environmental conditions by escaping from them
temporarily
• A long-term strategy is to enter a state of reduced
activity called dormancy during periods of
unfavorable conditions like winter or drought
• Another strategy is to move to a more favorable
habitat called migration
Escape from unsuitable
conditions
• dormancy
• migration
Niche
• A niche is the role or position a
species has in its
environment—how it meets its
specific needs for food and
shelter, how and where it
survives, and where it
reproduces in its environment.
• A species’ niche includes all its
interactions with the biotic and
abiotic parts of its habitat
Niches
• Generalists are
species with broad
niches
• Animals that can be
found in many
habitats
• They can tolerate a
range of conditions
and use a variety of
resources
• Specialists that have
a narrow niche
• Organism that is only
found in certain
places
• Mostly due to food
sources
• Generalists: The
Virginia opossum
found across US, feeds
on most anything
from eggs & dead
animals to fruits &
plants
• Specialists:
The koala of Australia
feeds only on the
leaves of a few species
of eucalyptus trees
• Specialists are consumers that primarily eat one specific
organism or a very small number of organisms.
• Generalists are consumers that have a varying diet.
Habitat
• A habitat is a place an
organism lives out its
life
Nutrition & Energy
Flow
Section 2
The Producers: Autotrophs
• The ultimate source of the
energy for life is the sun
• Plants use the sun’s
energy to manufacture
food in a process called
photosynthesis
• An organism that uses
light energy or energy
stored in chemical
compounds to make
energy-rich compounds is
a producer, or autotroph
The Consumer: Heterotrophs
• An organism that cannot
make its own food and
feeds on other organisms
is called a Heterotrophs or
consumers
• Heterotrophs include:
organisms that feed only
on autotrophs, organisms
that feed only on other
heterotrophs, and
organisms that feed on
both autotrophs and
heterotrophs
Herbivores
• Herbivores are
heterotrophs that feed
on only plants
Carnivores
• Carnivores are
heterotrophs that feed
on only meat
American Black Bear
Are carnivores even though they
Feed on berries
Omnivores
• Omnivores are
heterotrophs that feed
on both plants and
animals
badger
Scavengers
• Scavengers are
heterotrophs that feed
on animals that have
already died
Decomposers
• Some organisms, such as
bacteria and fungi, are
decomposers
• Decomposers break down
the complex compounds
of dead and decaying
plants and animals into
simpler molecules that
can be more easily
absorbed
Other types of relationships
Symbiosis
• The relationship in which there is a close and
permanent association between organisms of
different species is called symbiosis
• Symbiosis means living together.
• Three kinds of symbiosis are recognized:
1. Mutualism
2. Commensalism
3. Parasitism
Mutualism
• Mutualism: is a
symbiotic relationship
in which both species
benefit
Commensalism
• Commensalism: is a
symbiotic relationship
in which one species
benefits and the other
species is neither
harmed nor benefited.
Parasitism
• Parasitism is a symbiotic
relationship in which a
member of one species
derives benefit at the
expense of another
species (the host)
• Parasites have evolved in
such a way that they
harm, but usually do not
kill the host species
Predator vs. Prey
• A predator is a type of
consumer. Predators
seek out and eat other
organisms.
• Predation is found in
all ecosystems and
includes organisms
that eat plants and
animals
• The animals that
predators eat are called
prey
Flow of Matter and Energy in Ecosystems
Autotrophs
Third-order
heterotrophs
First-order
heterotrophs
Secondorder
heterotrophs
Decomposer
Food Chain
• A food chain is a simple model that scientists use
to show how matter and energy move through an
ecosystem
• In a food chain, nutrients and energy move from
autotrophs to heterotrophs and, eventually, to
decomposers
• A food chain is drawn using arrows to indicate the
direction in which energy is transferred from one
organism to the next- uses 3 to 5 links
minnow → brim → bass
Food Chain in an Antarctic
Ecosystem
Trophic Levels
• Each organism in a food
chain represents a feeding
step, or trophic level, in
the passage of energy and
materials
• A food chain represents
only one possible route
for the transfer of matter
and energy through an
ecosystem.
Energy Transfer Through Trophic
Levels
Food Webs
• A food web
shows all the
possible feeding
relationships at
each trophic level
in a community
Food Web
in an
Antarctic
Ecosystem
Ecological Food Pyramid
• An ecological pyramid can show how energy
flows through an ecosystem
• The base of the ecological pyramid represents
the autotrophs, or first trophic level. Higher
trophic levels are layered on top of one another.
Cycles of LIFE
The Water Cycle
• Steps of the Water Cycle
•
•
•
•
Evaporation
Condensation
Transpiration
Precipitation
Water cycles through the
environment.
• The hydrologic, or water, cycle is the circular pathway of water on
Earth.
• Organisms all have bodies made mostly of water.
precipitation
condensation
transpiration
evaporation
lake
groundwater
surface
runoff
water storage
in ocean
• Oxygen cycles indirectly through an ecosystem by the cycling of other
nutrients.
oxygen
photosynthesis
respiration
carbon
dioxide
The Carbon Cycle
• The carbon cycle is the process through which carbon is cycled
through the air, ground, plants, animals, and fossil fuels.
• Large amounts of carbon exist in the atmosphere as carbon
dioxide (CO2).
• Carbon dioxide is cycled by green plants during the process known
as photosynthesis to make organic molecules (glucose, which is
food).
– Carbon is emitted by the burning of fossil fuels.
– Some carbon is stored for long periods of time in areas called
carbon sinks.
The Nitrogen Cycle
• Nitrogen is used by living organisms to produce a number of
complex organic molecules like amino acids, proteins, and
nucleic acids.
• The amount of nitrogen found in the atmosphere, where it
exists as a gas (mainly N2), plays an important role for life.
Nitrogen Cycle
• The nitrogen cycle mostly takes place underground.
– Some bacteria convert
gaseous nitrogen into
ammonia through a process
called nitrogen fixation.
– Some nitrogen-fixing bacteria
live in nodules on the
roots of plants; others live
freely in the soil.
soybeans
• The phosphorus cycle takes place at and below ground level.
– Phosphate is released by the weathering of rocks.
– Phosphorus moves through the food web and returns to
the soil during
decomposition.
rain
– Phosphorus leaches
geologic uplifting
into groundwater
weathering of
from the soil and
phosphate from rocks
runoff
is locked in
plants
sediments.
animalsphosphate
phosphate in solution
– Both mining and
in soil
leaching
agriculture add
phosphorus into
sedimentation
decomposers
forms new rocks
the environment.