INTRODUCTION TO ECOLOGY
Biology Class
What is Ecology?
The study of how
organisms interact
with their environment
 All organisms must
interact with both
living and nonliving
things that surround
them.

Levels of Organization

To add to our list of the levels of organization:
 Tissues Organs 
Organ Systems  Organisms 
Population  Community 
Ecosystem  Biosphere
Cells
The environment


Made up of all the living
and nonliving things that
surround an organism.
Vocabulary:
Abiotic
Factors
Biotic Factors
Environment vs Habitat
Many species can survive
in more than one
environment.
 But each species has its
“home” or habitat.
 Fish may be able to live
in fish tanks, but would
rather live in the wild

Basic Concept of Ecology
The fundamental idea behind the study of
ecology is that all organisms are
interdependent.
 They interact with one another and the
physical environment.

What do organisms need to survive?

Basic requirements
for survival include:
 Food
 Water
 Shelter
Competition

An important aspect
of the struggle for
survival involves
competition for
limited resources
 Food
 Water
 Shelter
 Sunlight
Limiting Factors
Limiting factors are
factors that affect
the population size
of a species in a
specific
environment.
 They can be abiotic
or biotic.

Predator – Prey relationship



Predators are a biotic
limiting factor.
They control population
size by feeding on
prey.
There is a delicate
balance that needs to
be maintained.
Carrying Capacity

When all the limiting
factors are considered
together we can
determine the maximum
number of organisms
that can survive in an
area.
How do we determine the Carrying
Capacity of a Species?


All limiting factors must
be taken into
consideration.
It is very difficult to
determine the actual
carrying capacity.
The Lesson of the Kaibab Deer

Purpose:
 to graph data on the Kaibab
deer population of Arizona
from 1905~1939
 to analyze the methods
responsible for the changes
in the deer population
 to propose a management
plan for the Kaibab deer
population
Kaibab Forest: North Rim of the Grand Canyon
Key Idea


All organisms have the
ability to produce
populations of unlimited
size
But their environment
keeps their numbers in
check.
Review of Types of Nutrition
Autotrophic
 Heterotrophic

Which is heterotrophic and
which Autotrophic?
Categories of Populations

Populations are
labeled by the
function they serve in
the ecosystem
Producers
Consumers
Decomposers
So what is a Food Chain?
A food chain shows a
one way flow of energy
in an ecosystem
 It may not be the only
way energy flows in the
ecosystem

Food Webs



When all of the food chains of an ecosystem are
considered we can draw up a food web
It shows all of the possible paths that energy can
take in an ecosystem
It also shows how organisms are dependant on each
other in the ecosystem
Recycling
Who is ultimately responsible for the
recycling of nutrients?
Decomposers
 What gets recycled?
Minerals
Nutrients

Recycling
What else gets recycled?
Carbon Dioxide
Water
Carbon
 The energy from the Sun keeps the
cycle going

Carbon Cycle
Water Cycle
Nitrogen Cycle
Energy Pyramid
Energy Pyramid
There is more energy available at the bottom
 There are more organisms at the bottom
 There is less energy at the top
 There are less organisms at the top
 Energy is lost as you go up the pyramid,
mostly as heat

Energy
Pyramid
Symbiosis




Is a close ecological relationship between the
individuals of two (or more) different species.
Sometimes a symbiotic relationship benefits both
species
Sometimes one species benefits at the other's
expense,
Sometimes neither species benefits.
Types of Symbiosis





Mutualism: both species benefit.
Commensalism: one species benefits, the other is
unaffected.
Parasitism: one species benefits, the other is
harmed.
Competition: neither species benefits.
Neutralism: both species are unaffected.
http://www.marietta.edu/~biol/biomes/symbiosis.htm

The following table illustrates the correct use of
these terms in interactions between Species "A" and
Species "B". "+" denotes benefit to the species "0"
denotes no positive or negative effect "-" denotes
an undesirable effect of the interaction.