Ecology Chapter 1
Interactions
of Life
Biosphere
n
The biosphere is
the part of Earth that supports life
n
The biosphere includes
the top portion of the Earths crust, all the waters on Earths
surface, and the surrounding atmosphere.
n
The biosphere is made up
of different environments that are home to different kinds of organisms
n
Why isnt there life on
other planets?
Ecosystem
n
An ecosystem consists of all the
organisms living in an area and the nonliving features of their environment.
Ex:
everything in a meadow, a rotting log, a forest, etc.
n
Ecology is the study of
interactions that occur among organisms and their environment
Populations
n
A population is
made up of all the organisms in an ecosystem that belong to the same species
Ex:
centipedes under the rotting log, deer in Wasatch National Forest
n
A community is all
the populations in an ecosystem
Ex: Under the log, there are centipedes,
millipedes, worms, moss, algae, mold, mushrooms, etc.
Habitat
n
A habitat is the
place in which an organism lives
n
A habitat must provide
the kinds of food, shelter, temperature, and moisture the organism needs to
survive
n
Examples: a whale lives in the ocean, you live in your
house or apartment, a woodpecker lives in a tree
n
Many species can share a
habitat
Habitat assignment
n
Pretend you are a
non-human organism living in an ecosystem.
(Your teacher will give you the ecosystem.)
n
Draw a picture of what
you look like. (You can use be an existing organism or make one up.)
n
Draw your habitat.
n
Next to each living and
non-living feature of your habitat, describe in a sentence or two what it is
and why you need it in your habitat.
Competition
n
Competition is when two or more organisms seek the same resource at the same time.
n
Competition for food,
living space, or other resources can limit the population.
Ex: The Gila woodpecker lives on the saguaro
cactus in the Sonoran
Desert of Arizona
and Mexico. If too many woodpeckers or not enough sugauros, competition ensues and some woodpeckers do not live or reproduce.
Competition
n
Competition is usually
most intense between members of the same species.
Ex: Feeding the ducks on the Jordan
River
Ex: Antlers on the deer, bighorn sheep, etc.
Population Size
n
Population size indicates whether a population is healthy and growing.
n
Population density is the size of a population in a specific area
Ex: Countries with over 500 people per 2.6 km2
are India, Japan, the Philippines
and South Korea
Ex: The U.S. has 50-99 people / 2.6 km2
Ex: Mexico has 100-500 people / 2.6 km2
Ex: Canada has under 10 people / 2.6 km2
Population Size
n
There are two ways to
measure the size of a wildlife population
n
The Trap-mark-release
method
Trap an animal, mark it
somehow (a tag), and release it
n
Sample Count Method
Count the number of organisms in a certain area and multiply that
number by the entire area
Elements Affecting Population Size
n
A limiting factor
is any living or nonliving feature that restricts the number of individuals in
a population
Ex: rainfall,
predators, temperature,
availability
of sunlight
n
A carrying capacity
is the largest number of individuals of one species that an ecosystem can
support
Every population has a
carrying capacity
Once a population exceeds
carrying capacity, famine, disease, competition reduce its size
Elements Affecting Population Size
n
Biotic potential is the maximum number of offspring that parent organisms can produce
Ex: each apple has many seeds capable of becoming
new trees, where a peach only has one seed
n
Birth and Death Rates
Birthrate number of
births per 1000 people
Death Rate number of
deaths per 1000 people
When the birth rate
exceeds the death rate, the population grows
n
Ex: rapid-growth countries: Jordan
(3.3%), Uganda (2.9%), Zimbabwe (5.2%)
n
Ex: slow-growth countries: Germany
(-1.5%), Sweden (0.1%), United States
(0.6%)
Elements Affecting Population Size
n
Movement of organisms
into or out of an area affects a population size.
Ex: bird migration
n
When a population has
unlimited resources, it grows exponentially
n
The Human Population is
currently growing exponentially
Reaching Carrying Capacity
n
Resources are never
unlimited
n
Populations will reach a
carrying capacity the number of organisms of one species that an environment
can support
n
Populations follow an
S-shaped growth curve
The Sun
n
The sun is the source of energy that fuels all life on Earth either
directly or indirectly
n
Producers are organisms that use an outside energy source to make the
energy-rich molecules (sugar) they need
n
Most producers use the Sun and contain chlorophyll, a chemical
required for photosynthesis
All of Plant Kingdom
Carbon Dioxide + Water +
(Solar Energy) ΰ Sugar + Oxygen
n
Some producers, found near volcanic vents on the ocean floor, use
mineral molecules as energy sources for chemosynthesis
Some bacteria
Consumers
n
Consumers are organisms that cannot make their own energy-rich molecules
(sugar)
n
Consumers obtain energy
by eating other organisms
n
Herbivores eat plants
Ex: deer, rabbits, cows, Mr. Bliss
n
Carnivores eat other
animals
Ex: frogs and lions
n
Omnivores eat both plants
and animals
Ex: pigs and humans
n
Decomposers break down dead organisms
Ex: earthworms and bacteria
Food Chain
n
A food chain is a
model that shows the feeding relationships among the organisms in an ecosystem
In other words, a food
chain describes what eats what
Grass ΰ cow ΰ fox ΰ hawk
n
The arrows in a food
chain indicate the direction of energy flow
Food Web
n
A food web is a model that shows
all the possible feeding relationships among the organisms in a community
Combination of food chains in an ecosystem
Symbiosis
n
Symbiosis is any close relationship between species. There are three types.
n
Mutualism is a symbiotic relationship in which both species benefit
Ex: lichens are algae and fungus living together helping each other
live
Symbiosis
n
Commensalism is a symbiotic relationship in which one organism benefits and the
other is not affected
Ex: bacteria growing on
your nose, or barnacles on a whale
n
Parastitism is a symbiotic relationship in which one organism benefits and the
other is harmed
Ex: roundworms live in a
raccoons intestines
Niche
n
A niche is a
species unique requirements for survival
n
A niche has many
components
Habitat
Food
How it avoids danger
How and where it
finds a
mate
How it cares for its
young
Can you think of more?
n
NO two species can occupy
the same niche
Otherwise, competition
will ensue and one species must either move or it will die
Predator and Prey Relationship
n
A predator is a
consumer that captures and eats other consumers
Ex: lynx
n
A prey is the
organism that is eaten
Ex: hare
n
Predators limit the size
of prey populations, increasing the number of different species that can live
in an ecosystem
Keeps populations young
and healthy
Cooperation
n
Cooperative actions improve a species
survival
n
Example:
one deer warns the others of predators in the area
n
Example:
individual ants perform different tasks required for the survival of all