CHAPTER 14Interactions in Ecosystems: Day One

Habitat versus Niche

Review!

• What is a habitat?

• All of the biotic and

abiotic factors in the

area where an

organism lives.

• Examples: grass,

trees, and watering

holes!

• Where it lives!

Habitat versus NicheReview!

• What is a niche?

• Composed of all of the physical, chemical,

and biological factors that a species needs

to survive

• Niche includes: type of food a species eats,

tolerating certain types of abiotic conditions,

and a species’ behavior.

• How it lives!

• Habitat is like an address in an ecosystem

and a niche is like the job in an ecosystem.

Resource availability

• Provides structure to communities

• What is a community?

• Different groups of species

• Many species share similar habitats and use some of the same resources

• Florida Everglades

Competitive Exclusion

• Can present a problem

if two species use the

same resource in the

same way

• One species will

always be better

adapted to the

environment.

Competitive Exclusion

• States that when two species

are competing for the same

resources, one species will be

better suited to the niche, and

the other species will be pushed

into another niche or become

extinct.

• Example:

• In Great Britain, North

American gray squirrel (better

suited) introduced and pushed

out the native European red

squirrel.

• Caused red squirrel population

to decline rapidly.

Other outcomes from competitive

exclusion

• Niche partitioning:

• Divide resources based on competitive

advantages

• Evolutionary response:

• Different sizes of teeth could affect the way they

eat

Competitive Exclusion Principle

• http://nicolellawhhs.weebly.com/unit-5-chapter-14-

interactions-in-ecosystems.html

Ecological equivalents

• Are species that occupy

similar niches but live in

different geographical

regions.

• Examples: Mantella frog of

Madagascar and poison

dart frog of South America

• Both have the same niche

in similar habitats, but will

never compete for the

same resources because

they live in different

geographical regions.

Community Interactions

• Competition and

predation are two

important ways in which

organisms interact.

• Competition occurs when

two organisms fight for

the same limited

resource.

Competition

• Two types of

competition:

• Interspecific

competition:

• Competition

between two

different species

(competing for

space)

• Examples: cats

and dogs

Competition

• Two types of competition:

• Intraspecificcompetition:

• Competition between members of the samespecies

• Examples: male birds, lions

Predation

• Process by which one organism captures and

feeds upon another organism.

Timber Rattlesnake

More Community Interactions

• Symbiosis:

• Any relationship where two species live closely

together and interact.

• 3 types:

• Mutualism

• Commensalism

• Parasitism

Relationships Between Organisms

• http://nicolellawhhs.weebly.com/unit-5-chapter-14-

interactions-in-ecosystems.html

Ticket Out the Door

1. Complete the table about factors that influence ecosystems.

2. When does competition occur?

3. What is a resource?

4. What is the competitive exclusion principle?

5. What is predation?

6. When predation occurs, what is the organism called that does the killing AND eating, and what is the food organism called?

Type of Factor Definition Examples

Biotic Factors

Abiotic Factors

CHAPTER 14Interactions in Ecosystems: Day One

Continued…

Mutualism

• Both species benefit

from the relationship.

• Example:

• Ants and aphids:

Ants get a sugary

substance from the

plants while the plant

receives protection

from the ants

Commensalism

• One organism benefitswhile the other is unaffected.

• Example:

• Barnacles on whales: Barnacles “hitch” a ride on the whale gathering food during transport; the whales receives nothing out of the relationship

Parasitism

• One organism benefits

while the other is

harmed.

• Examples:

• Flea and dog: Flea gets

home/food while the

dog is harmed because

the flea feeds on its

blood!

Parasites

• Two types of parasites:

• Ectoparasite: lives on the outside of an

organism, attaching itself to the outside

of the host

• Examples: fleas, ticks, and leeches

• Endoparasite: found on the inside of

living organisms, feed on nutrients

ingested by their host

• Examples: tapeworms and hookworms

Symbiotic Relationships – Untamed

Science• http://nicolellawhhs.weebly.com/unit-5-chapter-14-

interactions-in-ecosystems.html

Ticket out the Door1. Determine which ecological factors are a part of a lion’s niche and which are a

part of a lion’s habitat by placing the above items in the correct column.

a. Items: food, hunting behavior, other lions, trees, watering hole, wildebeast,

zebra, sand, temperature, grass, savanna

2. What are the three possible outcomes of competitive exclusion?

3. What are ecological equivalents?

4. Complete the table about main classes of symbiotic relationships.

5. The organism from which a parasite obtains nutritional needs is called a(an)

_________________________.

Habitat Niche

Class Description of Relationship

mutualism

commensalism

parasitism

CHAPTER 14Interactions in Ecosystem: Day Two

Populations• What is a population?

• A group of the same species of

organism living in the same place.

Characteristics of Populations

• How do populations grow?

• Four important characteristics of a population are:

• Geographic distribution

• Population density

• Growth rate

• Age structure

Geographic Distribution

• May also be called it’s

range

• Describes the area

inhabited by a

population

• Varies in size

depending upon the

type of organism

Geographic dispersion

• Shows how individuals in a population are

spaced

• Allows ecologists to study population

dispersion

• Way in which individuals of a population are

spread in an area or a volume

• Three types of population dispersion:

• Clumped dispersion

• Uniform dispersion

• Random Dispersion

Clumped dispersion

• Individuals live

close together in

groups in order to

facilitate mating,

gain protection, or

access food

Uniform dispersion

• Individuals living at

specific distances from

one another

• Caused by territoriality

and intraspecific

competition

Random dispersion

• Individuals are

spread

randomly within

an area or

volume

Population Dispersion

• http://nicolellawhhs.weebly.com/unit-5-chapter-14-

interactions-in-ecosystems.html

Population density

• Number of individuals per unit area

(defined space)

• Varies greatly depending on the species

and ecosystem

• Measures the “crowdedness” of an area

• Population density =

# of individuals

area (units2)

Population growth

• Affected by three factors

• Number of births

• Number of deaths

• Number individuals

that enter and leave the

population

• Immigration – movement

INTO an area

• Emigration – movement

OUT of an area

Ticket Out the Door

1. What are four main characteristics of a population?

2. What is a population’s geographic distribution?

3. Another term for geographic distribution is

____________________.

4. What is population density?

5. What three factors affect population size?

6. If more individuals are born than die in any period of time,

how will the population change?

7. Complete the table about changes in population size.

Type of Change Definition Resulting

Change in Size

Immigration

Emigration

CHAPTER 14Interactions in Ecosystem: Day Two

Continued…

Population growth based on

available resources

• Growth is a function of

the environment

• Directly determined by

the amount of resources

available

• Two distinct types of

population growth

• Exponential

• Logistic

Exponential growth

• Population has abundant

space and food

• Occurs when the individuals

in a population reproduce at

a constant rate

• Lack of limiting factors

(causes population growth to

decrease)

• Shown as a J-shaped curve

in a graph

• Examples: bacteria!

More on exponential growth

• When a population has unlimited

resources and continues to grow

to its full living potential, it is

called its biotic potential.

• A population that has reached

biotic potential has reached its

maximum reproductive

capacity.

• That means it has reproduced

as much as it can!

Logistic Growth

• Occurs when the population’s

growth slows or stops following

a period of exponential growth

• Most realistic

• Caused by resources becoming

less available

• Influenced by limiting factors

• Can slow down when birthrate

decreases or death rate

increases

• Represented as an S-shaped

curve

Carrying Capacity

• Represented as K

• Largest number of

individuals that a

given environment

can support

• Can change when

the environment

changes

•Region A= very close to exponential growth•Region B= declining birthrate; inc. death rate•Region C= pop. reaches K; usually fluctuates around Carrying Capacity

Limiting factors

• Is a factor that causes population growth to

decrease

• Two types of limiting factors:

• Density-dependent

• Density-independent

Density-Dependent Factors• Depends on population size

• Becomes limiting only when the

population density reaches a

certain level

• Density is the number of

organisms per unit area

• Best seen when population is large

and dense

• Do not affect small, scattered

populations

• Examples: competition, predation,

parasitism, and disease

Competition

• Occurs if crowded organisms compete for food,

water, space, sunlight, and other essentials

• Can occurs between members of the same

species

• Can also occur between members of different

species…remember no two species can occupy

the same niche in the same place at the same

time

Effect of Predation

• Population size often

controlled by

predation

• Takes place in the

predator-prey

relationship

• Best mechanism of

population control

Parasitism and Disease

• Limit growth of

population

• Take nourishment at

the expense of their

hosts often

weakening them and

causing disease and

death

Density-Independent Factors

• Affect all populations

regardless of size

• Examples: unusual weather,

natural disasters, seasonal

cycles, and human activities

• Can see a population crash

• Dramatic decline in the

population size over time

Age Structure• Population growth depends on how many people of different ages make up a given population.

• Populations with large numbers of young offspring have greater potential for rapid growth

• Population Pyramids or Age-Structure Diagrams show age structure in a population.

Patterns of Population Growth

• The scientific study of human populations is

called demography

• Examines the characteristics of human

populations and attempts to explain how

those populations will change over time

• Birthrates, death rates, and the age

structure of a population help predict why

some countries have high growth rates

while other countries grow more slowly

Human Population Growth• It took from the beginning of mankind to around 1800 for the human population to reach 1 billion.

• In the last 200 years, the human population has reached just over 6 billion.

• The U.N. estimates the world’s population to be 12.5 Billion by 2050.

• What effects will these numbers have on the Earth? Other forms of life?

The Demographic Transition• Over the past century, population growth in the US, Japan, and much of Europe has slowed dramatically.

• One hypothesis as to why these countries have slowed in their growth is the demographic transition (a dramatic change in birth and death rates).

• As countries modernize, there are advances in nutrition, medicine, and sanitation.

• These result in more children surviving into adulthood and more adults living to old age.

• These changes lower the death rate and begin the demographic transition.

Population Biotic Potential

• http://nicolellawhhs.weebly.com/unit-5-chapter-14-

interactions-in-ecosystems.html

Ticket out the Door

1. How will a population change if there is abundant space and food and if the population is protected from predators or disease?

2. When does exponential growth occur?

3. When does logistic growth occur?

Word Bank:

Births Emigration Deaths Immigration

4. When resources are abundant in a particular area, individuals may move into the population of this area. This movement of individuals into a population from a different population is called __________________.

5. A very cold winter has left many deer in a population hungry and sick. By the end of the winter, this population will likely decrease because of ____________________.

6. A deer population experiences growth when the rate of reproduction increases. This change in population size is due to ___________________.

7. As humans move into their territory, many members of a deer population move away and join other herds. This movement of individuals out of a population into a new population is called _______________________.

CHAPTER 14Interactions in Ecosystems: Day Three

Ecological succession• Succession means the

sequence of biotic

changes that regenerate a

damaged community in a

previously uninhabited area

• Ecosystems are constantly

changing in response to

natural and human

disturbances.

• When an ecosystem

changes, older organisms

gradually die out and new

organisms move in.

Ecological succession

• Can result from slow changes in the

physical environment

• Sudden natural disasters or human

activities also play a role in ecological

succession

• Ecological succession can be

• Primary

• Secondary

Primary succession

• Establishment and development of an

ecosystem in an area that was previously

uninhabited

• Occurs on land where no soil exists

• Occurs on surfaces formed as volcanic

eruptions build new islands or cover the

land with lava rock or volcanic ash

• Can also occur on bare rock

Primary succession

• First, lichens that do not

need soil to survive grow on

rocks

• Lichens are made up of

fungus and algae; helps

break up rocks

• Next, mosses grow to hold

the newly made soil

• Each of these are known as

a pioneer species

• Meaning these are the first

species to populate an area

Primary succession

• Soil starts to form as

lichens, weather, and

erosion help break down

rocks into smaller pieces

• When lichens die they

decompose, adding

organic matter to the

rock to make soil

Primary succession

• Simple plants like mosses and ferns can grow in the

new soil

Primary succession

• Simple plants die, adding more nutrients to the soil

• Soil layer thickens

• Grasses and wildflowers begin to take over

Primary succession

• Grasses and wildflowers will die, adding nutrients to

the soil

• Shrubs and trees can survive now

Primary succession

• Insects, small birds, and mammals begin to move

into the area

• What was once bare rock, can now support an area

of life

Secondary succession• Begins in a place that already has soil and

was once the home of living organisms

• Occurs faster and has different pioneer

species than primary succession

• Often see this after a natural disaster such

as a forest fire or volcano

Climax community

• A stable group of plants and animals that is the end

result of the succession process

• Final and stable community

• Does not always mean big trees

• Grasses in prairies

• Cacti in deserts

Climax Communities

Climax Communities

Ecological Succession

Ticket Out the Door

1. What is ecological succession?

2. What is primary succession?

3. The first species to populate an area when primary

succession begins are called _________________.

4. When a disturbance changes a community without

removing the soil, what follows?

5. An area that was once referred to as a climax

community without removing the soil, what follows?