Download Limits on Population

Ecosystem Interactions
Why can’t everybody just get
along…
Island of Surtsey
Born on November 14,
1963 from a volcano
near Iceland
Brand new ecosystem;
intensively studied
United Nations World
Heritage Site
Competition
Interaction between 2
or more organisms
fighting for the same
resource in a given
area
Can be within species
or between different
species
Predation
One organism eats
another for food
Prey are usually well
adapted to avoid
predators (speed,
quills, sense of smell,
aggressive displays,
mimicry, etc.)
Equilibrium
Populations stay the
same over time
(number of births =
number of deaths)
Animals have adjusted
to stresses put on them
Carrying Capacity
The maximum number
of individuals of a
species that can be
supported indefinitely
by an ecosystem
Different number for
each species
Oh Deer!
Human Population Histogram
Do you think human
population will exceed the
Earth’s CARRYING
CAPACITY?
What factors will limit our
population growth?
Limiting Factors
An environmental
factor that prevents an
increase in the number
of organisms in a
population
Abiotic: sunlight,
temp, etc.
Biotic: disease,
predators, etc.
“The Law of the Minimum”:
The nutrient in least supply
is the one that limits growth.
“The Law of Tolerance”:
An organism can survive
within (tolerate) a certain
range of an abiotic factor
(eg. Cold)
Population Density:
The Number of organisms in an area
Density-Independent
Factors:
- Affect members of a
population regardless of
population density. Ex:
Fire, flood
Density-Dependent
Factors:
- Affect populations
because of the density of
the population. Ex: Food
supply, water quality,
disease spread
Population Factors
Natality: The number of offspring (babies)
of species born in one year.
Mortality: The number of individuals of a
species that die in one year.
Immigration: The number of individuals of a
species moving into an existing population.
Emigration: The number of individuals of a
species moving out of an existing population
Open vs. Closed Populations
Open Population:
- All 4 factors [natality, immigration, etc.] are
at work on the population.
Closed Population:
- Only mortality and natality are at work.
Population Growth=
(natality + immigration) - (deaths + emigration)
Open vs. Closed Populations
Jackson Park would be an example of an
open population – animals can come and go
What would be an example of a closed
population?
– Zoo
– Fenced yard
- farm field
- wildlife preserve
Know your Relationships!
P 54…copy definitions!
Competition
Predation
Mutualism
Parasitism
Commensalism