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First Unit: Ecology
The World Around Us
Biology is the study of LIFE
There is no one all-inclusive
definition of life. Instead,
biologists describe life by
describing characteristics of living
organisms.
Nutrition (autotrophic and heterotrophic):
how an organism obtains materials
necessary for growth, energy, repair,
maintenance
autotrophic—self feeders (plants)
heterotrophic—need to take food in
(animals)
Organisms have the ability to maintain
HOMEOSTASIS, which is a state of
internal regulation and balance. They do
this by way of DYNAMIC EQUILIBRIUM, a
way of constantly checking and altering
internal systems in order to maintain
homeostasis. If these systems are
disrupted, the organism is open to disease
Levels of organization
Atoms Molecules  Organelles  Cells 
Tissues  Organs  Organ Systems 
Organisms  Population  Community 
Ecosystem  Biomes  Biosphere
Ecology
• The study of the relationships between
organisms and between organisms and
their environment
Requirements of an ecosystem
1. There must be a constant flow of energy
into the ecosystem and there must be
organisms that can use this energy to
make organic compounds
2. There must be a cycling of materials
between the living organisms and the
environment
Biotic vs. Abiotic Factors
Biotic factors: these are all the living
elements of an ecosystem…plants,
animals, bacteria, fungi, etc.
Abiotic factors: these are all the parts of an
ecosystem that have not nor ever will be
alive. Examples: light intensity, pH, soil
type, availability of minerals, amount of
water, temperature
ABIOTIC FACTORS are also called
LIMITING FACTORS. They determine
which plants can live in an area, and plants
in turn determine which animals can
survive in an area.
(welcome to the land of biology, where many words overlap in their meaning!!)
Types of interactions in an
ecosystem
Nutritional relationships: involve the transfer
of nutrients from one organism to another
a. autotrophs—make their own food. Also
called producers (plants/algae)
b. Heterotrophs—cannot make their own
food and therefore must ingest their food.
This includes all of the following
categories:
c. Saprophytes/saprobes—obtain their nutrients
from the remnants of other organisms.
Fungus, Bacteria, Invertebrates (the FBI)
d.Herbivores--animals that feed exclusively on
plant material (cow, deer)
e.Carnivores—animals that feed exclusively on
other animals
• Predators: catch, kill, and consume their food
• Scavengers: feed on the remains of animals
that they have not killed
f. omnivore—feeds on both plant and
animal material
Symbiotic Relationships
Where different species of organisms live
together in close association
1. Commensalism
• One organism benefits, one is not affected
• Barnacles on whales
2. Mutualism
• Both organism benefit
• Lichen (algae and fungus together)
3. Parasitism
• One organism benefits, the other is harmed
• Parasite lives on a host
• Tapeworms, mosquitoes, fleas
Energy flow relationships
In order for an ecosystem to be selfsustaining, there must be a flow of energy
between organisms
This flow is visualized in the following ways:
1. Food Chains
• Series of organisms
through which food
energy is passed
• PRODUCER is always the first stage of a
food chain. It will be an autotroph (green
plant)
• All other steps are consumers
(heterotrophs)
• Primary consumer must be
herbivore/omnivore, secondary must be
onmivore/carnivore
• DECOMPOSERS are always part of a food
chain but almost never included. They can
interfere with any stage of a food chain as
they break down dead organisms and
return the nutrients to the soil.
2. Food Web
• A series of interconnected food chain
• Shows a truer
picture of the
relationship between
organisms
3. Pyramid of energy
• Greatest amount of
energy is always in the
producer level
• Only about 10%
is passed to each
new level
4. Pyramid of biomass
• Less energy at each
level means that less
organic matter
(biomass) can be at
each level
Cycles of Materials
A major rule of a self-sustaining ecosystem
is that various materials must be recycled
between organisms and the abiotic
environment
Carbon-Hydrogen-Oxygen Cycle
GLUCOSE
OXYGEN
PHOTOSYNTHESIS
DECAY
AEROBIC
RESPIRATION
WATER
CARBON
DIOXIDE
BURNING
Water Cycle
The Nitrogen Cycle
• Nitrogen is necessary for
proteins and DNA
• Involves decomposers
• Many legume plants
Ecosystem Formation
This is when the environment undergoes a
severe environmental catastrophe that
results in the ecosystem reverting to a
more primitive status. When left alone
again, it goes through a series of changes.
Given enough time, these changes will lead
to another stable environment that will
remain until another catastrophe occurs.
Ecological Succession
• Pioneer organisms: the first plants to
populate a given area—often lichen
Ecological succession,
continued
• The pioneer organisms help to make an
area healthy enough to support other life
forms. PO are often followed by grasses,
shrubs, conifers (cone-bearing trees), and
deciduous (leaf-bearing) trees
Ecological Succession, con’t
• A CLIMAX COMMUNITY is the last
community that will develop and this is the
collection of plants and animals that will
exist in an area until another
catastrophe occurs. A CC is
stable and long lasting—and
the CC defines what the biome
is.
Abiotic Factors
are the primary factors in controlling which
plants and, therefore, which animals will be
in an ecosystem. These factors also
regulate the CARRYING CAPACITY of an
area, which is the number of members of a
species that an area can support.
Competition
• While the environment is being re-established,
COMPETITION occurs. This is the struggle
between different species for the same limited
resources. The best adapted species will win
and survive, while the other will not flourish, and
perhaps die out.
• ONLY ONE SPECIES CAN EXIST PER NICHE
• Example: grey squirrels and red squirrels
Biodiversity
• To help an ecosystem stay healthy, it
should have a high level of
biodiversity…this is a measure of the
number of different species located in one
area. The greater the biodiversity, the more
stable of an ecosystem.
Niche
• This is the role an organism plays. The
niche includes habitat, reproductive habits,
food choices, hunting strategies,
interactions with other species.
Habitat
• The area where an animal lives is called its
habitat. Habitats are specific to each
species, but species’ habitats can overlap.
BIOMES
• Once a climax community is established,
the biome can be determined. Biomes are
large geographical areas that have similar
plant life and abiotic factors.
Tundra
•
•
•
•
Permanently frozen subsoil
Lichen, moss, caribou
Cold, cold, cold!
North Pole
Taiga
• Long, severe winters
• Conifers, moose, black bear
• Siberia, northern
Canada
Temperate Deciduous Forest
• Deciduous trees, cold winter, warm
summer
• Squirrel, fox, deer
• Northeast USA
Tropical Forest
• Heavy rainfall, warm temperatures, broadleaved plants
• Monkeys, leopards, toucan
• Brazil
Grassland
• Also known as “plains,””savannah”
• Grasses, buffalo, prairie dogs
• The America
mid-west, African
plains
Desert
• Sparse rainfall, extreme temperature
fluctuations
• Cactus, drought resistant
shrubs, lizards
• American southwest
Terrestrial Biomes
• are determined
by altitude and
latitude.
Aquatic biomes,
the most important being the OCEANS, are
extremely stable.
Characteristics:
1. Most stable environment
2. Absorbs and holds vast amounts of solar
heat
3. Contains a supply of nutrients and
dissolved salts
Aquatic Biomes, con’t
4. Habitat for a large number of species
5. **** Most of the photosynthesis on earth
occurs in the ocean***
Freshwater biomes (lakes, rivers) often
undergo succession towards a terrestrial
community
Humans and the Biosphere
Humans are the only organisms on
the planet who have such an
extreme capacity to change their
environment
Negative Aspects
1. Extinction
2. Importing invasive organisms (
3. Wildlife exploitation
4. Poor land management
5. Urbanization
6. Pollution (fossil fuels, acid rain, trash)
7. Biomagnification
ALL CAUSED BY OVERPOPULATION!!
zebra mussels, purple loosestrife
)
Positive Aspects
1.
2.
3.
4.
5.
6.
Population controls
Conservation of resources
Pollution controls
Species preservation
Biological controls ***
Learning from our mistakes and fixing
them
Changes for the future:
• Authors (Rachel Carson, Thoreau, Abby)
• Visionaries (Leopold, Muir, Roosevelt,
Edward O. Wilson)
• Organizations (ADK, Sierra Club)
• Recycled products and more efficient
machines (hybrid vehicles)