Studying the Web of Life

Ecology – the study of the interactions
between organisms and their
environment

Environments have 2 parts:
Biotic – living things in environment
 Abiotic – physical factors of environment
(water, soil, light, temperature, etc.)

Levels of Environmental Organization
1.
Organism – single individual
Levels of Environmental Organization
2. Population – group of individuals of the
same species that live together in the
same area at the same time
- individuals in a population compete with
one another for food, nesting space, and
mates
Levels of Environmental Organization
3. Community – consists of all the
populations of different species that live
and interact in an area
- different populations in a community
depend on each other for food, shelter,
and many other things
Levels of Environmental Organization
4. Ecosystem – community and its abiotic
environment.
Levels of Environmental Organization
5. Biosphere – part of the Earth where life
exist
Living Things Need Energy
All living things need energy to survive.
 Organisms can be divided into 3 groups
based on how they obtain energy:

1.
2.
3.
Producers – organisms that use sunlight
directly to make food
Consumers – organisms that eat
producers or other organisms
Decomposers – organisms that get
energy by breaking down dead or
decaying organisms
Producers
Use photosynthesis
 Mostly plants, but also algae and some
bacteria

Consumers





Cannot use sun’s
energy directly
Herbivore – eats
plants
Carnivore – eats
animals
Omnivore – eat both
plants and animals
Scavengers – feed
on bodies of dead
animals
Decomposers
Bacteria and fungi
 Extract the last bit of energy from dead
organisms and produce simpler
materials
 Nature’s recyclers

Food Chains

Food Chains – represents how the
energy in food molecules flows from one
organism to the next
Food Webs

Food Web – many energy pathways
between organisms
Energy Pyramid

The loss of energy at
each level of the
food chain can be
represented by an
energy pyramid
 Each level uses 90%
of the energy it
obtains, so only 10%
of the energy is
passed along to the
next level
Habitat and Niche
Habitat – the environment in which an
organism lives
 Niche – an organism’s way of life within
an ecosystem


Includes its habitat, food, predators,
organisms with which it competes, how the
organism affects and is affected by abiotic
factors in its environment
Interactions with the
Environment


An organism interacts with biotic or abiotic
factors in its environment that can control
the size of its population
Limiting Factors – factors that influence
how large a population can grow to


Ex: food, water, living space, other natural
resources
Carrying Capacity – the largest population
that a given environment can support over
a long period of time
Interactions Among Organisms

4 main ways that species and individuals
affect each other:
1.
2.
3.
4.
Competition
Predators and Prey
Symbiotic relationships
Coevolution
Competition
When 2 or more individuals or
populations try to use the same limited
resource (ex: food, water, shelter, space,
sunlight, etc.)
 Can occur among individuals within a
population
 Can occur between populations of
different species

Predators and Prey


Prey – organism that is
eaten
Predator – organism
that eats the prey

Predator Adaptations –
Canines
Claws
Camouflage
Speed

Prey Adaptations –
Chemical combat
Camouflage
Speed
Trickery: false features
and mimicry
Symbiosis
Close, long-term association between
two or more species
 3 Main Groups

1.
2.
3.
Mutualism
Commensalism
Parasitism
Mutualism

Symbiotic
relationship in which
both organisms
benefit
 Examples:


You and a species
of bacteria in your
intestines
Coral and algae
Commensalism

Symbiotic
relationship in which
one organism
benefits and the
other organism is
unaffected
 Examples:

Sharks and
remoras
Parasitism




Symbiotic relationship in which one organism benefits
while the other organism is harmed
Parasite – organism that benefits
Host – organism that is harmed
Example:

Tomato hornworm and wasps
Coevolution

Long-term change that takes place in
two species because of their close
interactions with one another
Flowers and their
Pollinators
Yucca Moth and Yucca
Plants
Acacia Trees and
Acacia Ants