Download The study of interactions among organisms & their environment

ECOLOGY
• The study of interactions among organisms &
their environment
• Ecologists divide environmental factors that
influence organisms into 2 groups: ABIOTIC and
BIOTIC.
ABIOTIC
• NONLIVING PARTS OF THE ENVIRONMENT
• Ex: Water, light, temperature, air, soil
• Air is a mixture of 3 main gases: oxygen, carbon
dioxide, & nitrogen (used by plants & animals
• Soil type is determined by the amounts of
sand, humus, & clay that it contains
• Humus: decaying matter found in soil
BIOTIC
• Living or once-living organisms in the
environment
• Can be arranged into levels of organization:
1. organism
• 1 individual from a population
• Example: catfish
2. POpulation
• All the individuals of one species that live in
the same area at the same time.
• Example: All the catfish living in a lake at the
same time
3. community
• Populations of different species that interact
in some way
• Example: Population of bass and all the
species they interact with it
4. ecosystem
• All the communities in an area & the abiotic
factors that affect them
• Example: lake, pond, coral reef, forest, etc.
5. Biome
• Large region with plants & animals well
adapted to soil & climate of the region
• Example: Mountain, rainforests, tundra,
desert, grasslands, temperate forests (where
we live)
6. biosphere
• All the ecosystems on earth; the part of the
earth that supports life
• Example: Top part of the earth’s crust, all the
waters that cover the Earth’s surface, the
surrounding atmosphere, & all the biomes.
Interactions among living
organisms
1. Population size
• The number of individuals in a population
2. Population Density
• The number of
individuals in a
population that
occupy a definite area
Classroom population density
• Length of room (m) X width (m)
# of students
=A (in m2)
= how much space each person has
3. Population spacing
• How organisms are arranged in a given area
• Can be evenly, random, or clumped
EVEN
random
clumped
4. Limiting factors
• Any biotic or abiotic factor that limits the
number of individuals in a population
• Ex: drought, fewer plants, fewer nesting sites,
predators
• Food, water, & space are all factors in the
growth populations in an ecosystem
• If an environment had no limiting factors,
the population would INCREASE.
5. Carrying capacity
• Largest number of individuals of a species
that an environment can support &
maintain for a long period of time.
Energy flow through ecosystems
• Most of the interactions among members of
different species occur when one organism
feeds on another
• When one organism is food for another
organism, some of the energy in the first
organism (the food) is transferred to the
second organism (the eater).
producers
• Organisms that take in
& use energy from the
sun or some other source
to produce food.
• Examples: algae &
plants
Consumers
• Organisms that take
in energy when they
feed on producers or
other consumers.
decomposers
• Organisms that take
in energy from
organisms that have
died by breaking
down the remains of
organisms.
Are producers
Plants, bacteria,
and algae
Make food from water,
sunlight, and CO²
Means “self
nutrition”
Are consumers and
decomposers
Need food
Autotrophs
Both are
living
things
Need water,
sunlight, and air
Animals,
humans,
monkeys
Heterotrophs
Get food from
autotrophs
Means “other
nutrition”
Characteristics of Autotrophs vs.
Heterotrophs
• Movement of energy through a
community can be diagrammed
as a food chain or food web.
Food chain
• Simple way of showing how energy
passes from one organism to
another.
• Usually 3 or 4 links
Example of food chain:
1. Water plant
insects
bluegill
bass
2. Grass grasshopper frog
owl
snake
Energy pyramid
• Compares energy
available at each level of
the food chain in an
ecosystem
• As you move from level
to level, energy
decreases.
2. Food web
• Series of overlapping
food chains that exist
in an ecosystem
• More complete model
of feeding
relationships.
Other Ecological Terms to Know:
• Symbiosis is a close relationship that may
occur when two organisms of different
species live together.
• There are several different kinds of
symbiotic relationships:
1) Mutualism: Both species benefit. The two
organisms help each other. An example would
be a honey bee and a dandelion. The honey
bee gets to eat the pollen from the flower.
The dandelion uses the bee to spread its
pollen to another flower.
More Ecological Terms cont.
2) Commensalism: One species benefits. The
other species is unaffected. A common
example is an animal using a plant for shelter.
An American Robin benefits by building its
nest in a Red Maple tree. The tree is
unaffected.
3) Parasitism: Ones species benefits. The
other species is harmed. An example would be
a deer tick and a White-tailed Deer. The tick
gets food from the deer without killing it.
The deer is harmed by losing blood to the
tick, and possibly by getting an infected
wound or disease.
Cycles of matter
• Energy is not replaced, but recycled.
• Many important materials (water, carbon, &
nitrogen) make up your body & cycle
through the environment.
1. Water cycle
• Process of
evaporation,
condensation, &
precipitation
(see board for drawing)
2. Carbon cycle
• Follows various paths