Transcript population ecology

All living organisms are limited by
factors in the environment
CHAPTER 3.1 & 4.1
POPULATION ECOLOGY
In Chapter 2, you learned that
organisms depend on one another for
survival. You also learned about
abiotic factors and that abiotic factors
affect individual organisms.
How, then, might these factors affect
communities and populations?
Key Terms
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Population
Species
Limiting factor
Population growth rate
Carrying capacity
Biodiversity
1st Essential Theme
Interdependence
of Organisms
For populations
to grow & survive
they must have
resources
CHAPTER 2
REVIEW TERMS
 Population
is a group of
individuals of the same type (or
species)
 Species is a group of
organisms that can interbreed
and produce fertile offspring
P. 92-94
POPULATION DYNAMICS:
Measurements of populations
 Population
size = # of individuals
 Population density = # of individuals
per area
 Population range = total space
occupied by species
 Population dispersion = pattern of
spacing within an area
P. 97
POPULATION GROWTH RATE:
How fast a population grows
 Birthrate = # of individuals born in a given
amount of time
 Death rate = # of deaths that occur in the
population during a given period
 Migration = movement into/out of a
population
○ Immigration = movement in
○ Emigration = movement out
BIRTH
IMMIGRATION
DEATH
EMIGRATION
POPULATIONS GROW WHEN…
There are more births than
deaths and more
immigration than
emigration.
How does predation affect
populations?
 With
small predator numbers (wolf) how
is the prey (moose) population affected?
 With large prey numbers how is the
predator population affected?
 With large predator numbers how is the
prey population affected?
 With small prey numbers how is the
predator population affected?
Predator-Prey Relationship
Why does this happen?
 With
2 wolves and 24 moose,
how much competition for food
was there among the wolves?
 With 14 wolves and 10 moose,
how much competition for food
was there among the wolves?
P. 61
LIMITING FACTOR
 Any
biotic or abiotic factor that
restricts the numbers of organisms
○ Resource availability – how much food,
water, shelter, sun, soil…
○ Natural phenomena – tornadoes,
flooding, climate change, drought
○ Man-made disturbances – dam building,
pollution, deforestation
BIOTIC FACTORS ARE…
P. 94
DENSITY-DEPENDENT FACTORS
 Affect
a population with greater
magnitude or strength or rate
because of greater population density
 Usually include predation, disease,
parasites, and competition
Think – predation occurs more frequently and disease
spreads faster because the population is dense.
ABIOTIC FACTORS ARE…
P. 94
DENSITY-INDEPENDENT FACTORS
 Affect
a population with the same
magnitude or strength or rate regardless of
population size
 Usually include natural disasters, weather
& climate change, and human changes to
environment (pollution or dam building)
Think – fires, tornadoes, and pollution do not occur more often
or intensify in more dense populations.
2nd Essential Theme
Stability
Populations
maintain
stability in
response to
each other
Review Habitat & Niche
 Habitat
is the place.
 Niche is the place, what is eaten,
the lifestyle.
 Habitat : Address :: Niche : Job
FUNDAMENTAL NICHE
The full range of physical and
biological conditions in which an
organism lives and way in
which the organism uses those
conditions.
EXPONENTIAL GROWTH CURVE
Population growth is NOT
limited
 Takes on an J-shape
 Ideal and doesn’t
normally occur in most
populations
 What kinds of organisms
might have exponential
growth and why?

REALIZED NICHE
The range of resources a species
actually used; it’s a portion of the
fundamental niche.
 A species
may have to restrict its activity
to avoid predators, or competition with
other species may prevent it from using
a resource.
THIS RESTRICTED RANGE IS SET BY A…
CARRYING CAPACITY
 The
maximum number of
individuals that can be
supported by the ecosystem.
 The limit is determined by the
availability of resources and by
their interactions with other
organisms.
Populations grow, especially
during plentiful times
Population growth slows as
factors decrease survival
LOGISTIC GROWTH CURVE
Population growth is
limited by factors in the
environment
 Takes on an S-shape
 Marked by a carrying
capacity

What happens when there
is competition for a niche?
Competitive exclusion
(extinction), one species moves
out, or niche partitioning
(resource sharing)
3rd Essential Theme
Evolution
Genetic
variability
impacts
survival
P. 98
REPRODUCTIVE PATTERNS
 Species
of organisms vary in
the number of births per
reproductive cycle, in the age
that reproduction begins, and in
the life span of the organism.
○ R-strategist
○ K-strategist
P. 98
R-strategist
Small organism (fruit fly or a mouse)
 Short life span
 Produce many offspring
 Strategy is to produce as many offspring as
possible in a short time in order to take
advantage of some environmental factor
 Populations are controlled by densityindependent factors (changes in abiotic
factors)

P. 99
K-strategist (also called Carrying Capacity Strategy)
Large organism (elephant)
 Long life span
 Produce fewer offspring but invest a lot of care
 Strategy is to produce only a few offspring who
have a better chance of living due the care they
get from parents
 Populations are controlled by densitydependent (biotic factors)

Which are you?
R-strategist
K-strategist
P. 116-118
BIODIVERSITY
of life in an area – the #
of different species in that area
 Increases stability of an
ecosystem – why do you think
this is?
 Variety
P. 116-118
3 TYPES of BIODIVERSITY
 Genetic
diversity
○ Variety of genes in a population
○ Example: color of corn or maize
○ Increases the chances that some
species will survive changing
environmental conditions
P. 116-118
3 TYPES of BIODIVERSITY
 Species
diversity
○ # of different species and how
many individuals of each species in
an area
○ Example: medicinal plants in the
rainforest
P. 116-118
3 TYPES of BIODIVERSITY
 Ecosystem
diversity
○ Variety of ecosystems present in
biosphere
○ Example: Jungles of Peru support
tropical birds, plants, mammals, etc
○ Ecosystem diversity results in
species diversity in a healthy
biosphere.