Unit One Standards
• S7L4. Students will examine the dependence of organisms
on one another and their environments.
• a. Demonstrate in a food web that matter is transferred
from one organism to another and can recycle between
organisms and their environments.
• b. Explain in a food web that sunlight is the source of
energy and that this energy moves from organism to
organism.
• c. Recognize that changes in environmental conditions can
affect the survival of both individuals and entire species.
• d. Categorize relationships between organisms that are
competitive or mutually beneficial.
Interactions Between Organisms
Competition
Within a species (INTRAspecies Competition)
• Members of a population compete with each
other for limited resources.
– Limiting Factors
• This competition determines carrying capacity
(the largest population an area can hold)
Competition
Between different species:
(INTERspecific
Competition)
EX: several species of birds
feed on the same
insects.
Some species may be
eliminated from the
community.
Competitive Exclusion Principle
• Two species
CANNOT coexist
in a community IF
their niches are
IDENTICAL.
• NICHE: ALL of the
biotic and abiotic
resources an
organism uses in
its environment.
Predator Prey Relationships
Prey: The organism that is
eaten.
Predator: The organism
that eats the prey.
Predator Prey Relationships
Predators and prey ADAPT to become better at
what they do.
This takes MANY, MANY generations
Plant Defenses Against Herbivores
Thorns or spines
Plant Defenses Against Herbivores
Irritating or toxic
chemicals
Broccoli =
bitter oils
Foxglove =
Digitalis
Tobacco =
Nicotine
Animal Defenses Against Predators
• Choices:
– Hiding
– Escaping
– Defending
Hiding: Camouflage
Blending with the background
Stick bug
Peppered Moth
Escaping: Deceptive Markings
Butterfly fish
Coral/King snakes
Automerisio Moth
Escaping: Warning Colors
Predators learn to avoid them:
Defending: Chemical or Mechanical
• Ted Video