UNIT 5
Chapter 14
Interactions in
Ecosystems
UNIT 5: ECOLOGY
Chapter 14: Interactions in Ecosystems
I. Habitat and Niche (14.1)
A. A habitat differs from a niche
1. habitat- all of the
biotic and abiotic factors
in the area where an
organism lives. (where a
species lives)
2. niche- composed of all the physical, chemical
and biological factors that a species needs to
survive, stay healthy, and reproduce. (how it lives
within the habitat)
a. Food- type of food species eats, how it
competes for food, and where it fits in the food
web.
b. Abiotic conditions- includes range of
conditions such as air temperature, amount of
water
c. Behavior- time of day
species is active, where
and when reproduces, etc.
B. Resource availability gives structure to a
community.
1. Competitive exclusion- when two
species are competing for same resources,
one species will be better suited to the niche,
and other species
will be pushed into
another niche or
become extinct.
3. Competitive exclusion can result in other
outcomes
a. niche partitioning- dividing of niche by
two competing species (e.g. top or tree, or
bottom of tree)
b . Evolutionary response- divergent evolution
resulting in selection of different successful traits.
c. Ecological Equivalents- species that occupy
similar niches but live in different geographical
regions.
Madagascar
South America
II. Community Interactions (14.2)
A. Competition and predation are two
important ways in which organisms interact.
1. Competition- occurs when two organisms fight
for the same limited resources.
a. Interspecific competition- competition
between different species
b. Intraspecific competition - competition
between organisms of same species
2. Predation- process by which one organism
captures and feeds upon another organism.
B. Symbiosis is a close relationship between
species (symbiosis- close ecological relationship
between two or more organisms of different
species that live in direct contact with one another)
1. Mutualism- both
species benefit
from one another
2. Commensalism- one receives an ecological
benefit from another, while the other neither
benefits nor is harmed.
3. Parasitism- similar to predation in that one
organism benefits while the other is harmed
III. Population Density and Distribution (14.3)
A. Population density is the number of
individuals that live in a defined area
1. Measurement of the number of individuals living
in a defined space.
2. Can calculate
B. Geographic dispersion of a population shows
how individuals in a population are spaced.
1. Population dispersion- way
in which individuals of a
population are spread in an area
or a volume.
2. Can be clumped, uniform,
or randomly dispersed
clumped
uniform
random
C. Survivorship curves help to describe the
reproductive strategy of a species
1. Survivorship curve- generalized diagram
showing the number of surviving members
over time from a measured set of births.
2. Gives information about life history of species
IV. Population Growth Patterns (14.4)
A. Changes in population’s size are
determined by immigration, births,
emigration, and deaths.
1. Size of populations are usually
changing
2. Four factors affect the size of a population
a. immigration- movement of individuals
into a population from another population
b. Births- births increase number of individuals in
population
c. Emigration- movement of individuals out of a
population and into another
d. Deaths- size of population decreases when
individuals die.
B. Population growth is based on available
resources
1. population growth determined by amount
of resources available.
2. Two types of population growth
a. Exponential growthoccurs when population
size increases dramatically
over period of time
Exponential growth
b. Logistic growth- begins with period of slow
growth, followed by brief exponential growth before
leveling off at a stable size.
1). Carrying capacity- maximum number of
individuals of a particular species that the
environment can support
2). Population crash- dramatic decline in size of
population over a short time
C. Biological factors limit population growth
1. Limiting factor-factor that has the
greatest affect on keeping down the size of a
population
2. Two categories of limiting factors
a. Density-dependent- affected by number of
individuals in a given area
1). Competition- compete for resources
2). Predation- population of predator can be
limited by available prey
3). Parasitism and disease- spread quickly
through dense populations
b. Density-independent limiting factorsaspects of environment that limit population growth
regardless of density
1). Unusual weather-can affect entire food
chain or web
2). Natural disasters- volcanoes, tsunamis,
tornados, hurricanes, etc.
3). Human activities- destruction of habitat,
introduction of non-native species
V. Ecological Succession (14.5)
A. Succession occurs following a disturbance
in an ecosystem
(succession- sequence of biotic changes
that regenerate a damaged community or
create a community in a previously
uninhabited area)
1. Primary succession- development of
ecosystem in areas that was previously uninhabited
a. pioneer species- first organism to move into
area like lichens and some mosses.
b. Series of steps: bare rock → pioneer species →
small plants → small animals → larger animals
and plants
2. Secondary succession- reestablishment of a
damaged ecosystem where soil was left intact
(after fire, hurricane, etc.)
a. Plants and animals that remain start the
process of regrowth.
b. dynamic process- are always changing the face
of an ecosystem
Chapter 14
Populations
Which of the following is NOT one of the four factors
that play a role in growth rate?
a.
immigration
b.
death rate
c.
emigration
d.
demography
Which of the following is NOT one of the four factors
that play a role in growth rate?
a.
immigration
b.
death rate
c.
emigration
d.
demography
One of the main characteristics of a population is its
a.
change over time.
b.
geographic distribution.
c.
dynamics.
d.
habitat.
One of the main characteristics of a population is its
a.
change over time.
b.
geographic distribution.
c.
dynamics.
d.
habitat.
Sea otters are important to the populations of
a.
kelp.
b.
sea urchins.
c.
killer whales.
d.
all of the above
Sea otters are important to the populations of
a.
kelp.
b.
sea urchins.
c.
killer whales.
d.
all of the above
There are 150 Saguaro cacti plants per square
kilometer in a certain area of Arizona desert. To
which population characteristic does this information
refer?
a.
growth rate
b.
geographic distribution
c.
age structure
d.
population density
There are 150 Saguaro cacti plants per square
kilometer in a certain area of Arizona desert. To
which population characteristic does this information
refer?
a.
growth rate
b.
geographic distribution
c.
age structure
d.
population density
Which of the following tells you population density?
a.
the number of births per year
b.
the number of frogs in a pond
c.
the number of deaths per year
d.
the number of bacteria per square millimeter
Which of the following tells you population density?
a.
the number of births per year
b.
the number of frogs in a pond
c.
the number of deaths per year
d.
the number of bacteria per square
millimeter
When organisms move into a given area from
another area, what is taking place?
a.
immigration
b.
emigration
c.
population shift
d.
carrying capacity
When organisms move into a given area from
another area, what is taking place?
a.
immigration
b.
emigration
c.
population shift
d.
carrying capacity
When organisms move out of the population they
were born in, it is known as
a.
emigration.
b.
abandonment.
c.
immigration.
d.
succession.
When organisms move out of the population they
were born in, it is known as
a.
emigration.
b.
abandonment.
c.
immigration.
d.
succession.
What occurs in a population as it grows?
a.
The birthrate becomes higher than the death
rate.
b.
The birthrate stays the same and the death
rate increases.
c.
The birthrate becomes lower than the death
rate.
d.
The birthrate and the death rate remain the
same.
What occurs in a population as it grows?
a.
The birthrate becomes higher than the
death rate.
b.
The birthrate stays the same and the death
rate increases.
c.
The birthrate becomes lower than the death
rate.
d.
The birthrate and the death rate remain the
same.
What is happening in a population as it decreases?
a.
The birthrate and the death rate remain the
same.
b.
The death rate becomes lower than the
birthrate.
c.
The death rate stays the same and the
birthrate increases.
d.
The death rate becomes higher than the
birthrate.
What is happening in a population as it decreases?
a.
The birthrate and the death rate remain the
same.
b.
The death rate becomes lower than the
birthrate.
c.
The death rate stays the same and the
birthrate increases.
d.
The death rate becomes higher than the
birthrate.
If immigration and emigration numbers remain equal,
which is the most important contributing factor to a
slowed growth rate?
a.
increased birthrate
b.
constant death rate
c.
decreased birthrate
d.
constant birthrate
If immigration and emigration numbers remain equal,
which is the most important contributing factor to a
slowed growth rate?
a.
increased birthrate
b.
constant death rate
c.
decreased birthrate
d.
constant birthrate
Which are two ways a population can decrease in
size?
a.
immigration and emigration
b.
increased death rate and immigration
c.
decreased birthrate and emigration
d.
emigration and increased birthrate
Which are two ways a population can decrease in
size?
a.
immigration and emigration
b.
increased death rate and immigration
c.
decreased birthrate and emigration
d.
emigration and increased birthrate
When individuals in a population reproduce at a
constant rate, it is called
a.
logistic growth.
b.
growth density.
c.
exponential growth.
d.
multiple growth.
When individuals in a population reproduce at a
constant rate, it is called
a.
logistic growth.
b.
growth density.
c.
exponential growth.
d.
multiple growth.
The various growth phases through which most
populations go are represented on a(an)
a.
logistic growth curve.
b.
exponential growth curve.
c.
normal curve.
d.
population curve.
The various growth phases through which most
populations go are represented on a(an)
a.
logistic growth curve.
b.
exponential growth curve.
c.
normal curve.
d.
population curve.
Which of the following describes how fast the human
population is growing?
a.
slowly
b.
The population is remaining stable.
c.
exponentially
d.
The population is decreasing.
Which of the following describes how fast the human
population is growing?
a.
slowly
b.
The population is remaining stable.
c.
exponentially
d.
The population is decreasing.
When the exponential phase of a logistic growth
curve of a population ceases,
a.
the size of the population drops.
b.
the size of the population stays the same.
c.
population growth begins to slow down.
d.
population growth begins to speed up.
When the exponential phase of a logistic growth
curve of a population ceases,
a.
the size of the population drops.
b.
the size of the population stays the same.
c.
population growth begins to slow down.
d.
population growth begins to speed up.
A biotic or an abiotic resource in the environment
that limits the size of a population is a
a.
carrying capacity.
b.
limiting nutrient.
c.
limiting factor.
d.
growth factor.
A biotic or an abiotic resource in the environment
that limits the size of a population is a
a.
carrying capacity.
b.
limiting nutrient.
c.
limiting factor.
d.
growth factor.
The number of organisms that an environment can
support over a relatively long period of time is called
a.
carrying capacity.
b.
logistic growth.
c.
exponential growth.
d.
limiting factor.
The number of organisms that an environment can
support over a relatively long period of time is called
a.
carrying capacity.
b.
logistic growth.
c.
exponential growth.
d.
limiting factor.
Which will reduce competition within a species’
population?
a.
fewer individuals
b.
higher birthrate
c.
fewer resources
d.
higher density
Which will reduce competition within a species’
population?
a.
fewer individuals
b.
higher birthrate
c.
fewer resources
d.
higher density
If a population grows larger than the carrying
capacity of the environment, the
a.
death rate may rise.
b.
birthrate may rise.
c.
death rate must fall.
d.
birthrate must fall.
If a population grows larger than the carrying
capacity of the environment, the
a.
death rate may rise.
b.
birthrate may rise.
c.
death rate must fall.
d.
birthrate must fall.
Each of the following is a density-dependent limiting
factor EXCEPT
a.
competition.
b.
predation.
c.
crowding.
d.
disease.
Each of the following is a density-dependent limiting
factor EXCEPT
a.
competition.
b.
predation.
c.
crowding.
d.
disease.
Which of the following is a density-dependent factor?
a.
earthquake
b.
disease
c.
emigration
d.
immigration
Which of the following is a density-dependent factor?
a.
earthquake
b.
disease
c.
emigration
d.
immigration
Human population growth has slowed down in
a.
China.
b.
the United States.
c.
India.
d.
Africa.
Human population growth has slowed down in
a.
China.
b.
the United States.
c.
India.
d.
Africa.
Demography is the scientific study of
a.
democratic societies.
b.
modernized countries.
c.
human populations.
d.
economic transitions.
Demography is the scientific study of
a.
democratic societies.
b.
modernized countries.
c.
human populations.
d.
economic transitions.
The demographic transition is change from high
birthrates and high death rates to
a.
exponential growth.
b.
a low birthrate and a low death rate.
c.
a low birthrate and a high death rate.
d.
indefinite growth.
The demographic transition is change from high
birthrates and high death rates to
a.
exponential growth.
b.
a low birthrate and a low death rate.
c.
a low birthrate and a high death rate.
d.
indefinite growth.
About 500 years ago, the world’s population started
a.
decreasing.
b.
to reach carrying capacity.
c.
growing more rapidly.
d.
to level off.
About 500 years ago, the world’s population started
a.
decreasing.
b.
to reach carrying capacity.
c.
growing more rapidly.
d.
to level off.
The human population experienced exponential
growth after
a.
agriculture began.
b.
plowing and irrigation began.
c.
the bubonic plague began.
d.
the industrial revolution began.
The human population experienced exponential
growth after
a.
agriculture began.
b.
plowing and irrigation began.
c.
the bubonic plague began.
d.
the industrial revolution began.
The anticipated human population by the year 2050
may be about
a.
7.8 billion.
b.
9 billion.
c.
9 trillion.
d.
78 billion.
The anticipated human population by the year 2050
may be about
a.
7.8 billion.
b.
9 billion.
c.
9 trillion.
d.
78 billion.
In countries like India, the human population is
growing
a.
exponentially.
b.
transitionally.
c.
logistically.
d.
demographically.
In countries like India, the human population is
growing
a.
exponentially.
b.
transitionally.
c.
logistically.
d.
demographically.
Most of the worldwide human population is growing
exponentially because
a.
they have not reached their exponential curve.
b.
they have not yet completed the demographic
transition.
c.
human populations do not conform to the
logistic model.
d.
science and technology have made it possible.
Most of the worldwide human population is growing
exponentially because
a.
they have not reached their exponential curve.
b.
they have not yet completed the
demographic transition.
c.
human populations do not conform to the
logistic model.
d.
science and technology have made it possible.