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Population Ecology
Chapter 47 Notes
Name ______________________________
Block __________ Date _______________
A _______population_______________________ is a group of organisms of the same species that live in a
particular area. Students in a classroom make up a population.
A _____limiting factor__________________________ is any condition that limits the size of a population.
There are 7 limiting factors:
1. Predation:___ one organism consumes another- hunt and kill_______________________________
2. Parasitism: ____on organims lives off another organims while the host is still alive______________
3. Competition for Food ____organisms fight over food___________________________________________
4. Pollution: ___________pollutants from humans________________________________________________
5. Availability of Water: ______droughts can affect availability______________________________________
6. Disease: __bacterial, viral infections (could be considered parasites also) and cancer type diseases_________
7. Climate: _________hurricanes, tornadoes, floods_____________________________________
Limiting factors can be categorized as two types: density-dependent and density-independent.
______density-dependent__________________________________ limiting factors limit a population only
when the population reaches a certain density. Examples are: predation, parasitism, compete for food, water &
disease
________density-independent________________________________ limiting factors affect a population in the
same way regardless of density. Examples are: climate & pollution
An exponential growth curve is shown to the right. Bacteria
exhibit exponential growth- they double with each division
and have rapid growth.
Label where the individuals start to multiply RAPIDLY.
# of bacteria
________exponential growth___________________________________ occurs when the rate of growth in
each new generation is a multiple of the previous generation.
Time
A population’s size changes over time. This change is known as a _____growth
rate___________________________. Growth rate depends on births, deaths, immigrations (organisms enter a
population) and emigrations (organisms leave a population).
The ________carrying capacity_________________________________ is the number of organisms that can be
supported by the environmental resources in an ecosystem.
50
40
A carrying capacity curve is shown to the right.
30
It illustrates that the environment can only produce
20
so much food and shelter for a population before
10
the population reaches an equilibrium- the same
0
number of births each year equal the same number of deaths.
Time
Another term for a carrying capacity graph is an ___S______ graph
because it is in the shape of an “S”.
There are a number of ways two populations of organisms interact with each other:
Definition
Example
competition
organisms try to make use of the
same resources
plants compete for water & sun light
Predation
one organism consumes & eats
another organism (prey)
hare & lynx
Parasitism
one organism feeds (parasite) on the tick & dog
tissue of another organism (host)- human & tapeworm
causing pain
mutualism (symbiosis)
each organism fills a need for the
other
birds & alligators- birds pick leeches
out of the alligators teeth
Commentalism
one organism reaps the benefits
while the other is unharmed
barnacle & a whale
Predation curve between the lynx (cat) and rabbit population.
: rabbit population
: lynx population
# of organisms
Interaction
Time
Time
Succession
When an area is wiped out by a
fire or is cleared down by humans,
it kills all of the plant & animal life.
When a community tries to
reestablish itself and begin to grow
again, is is known as
______succession____________________.
Primary succession is the first stage
of regrowth and the climax
community is when the community
has once again been established.
A _______boom & bust___________________ curve represents
exponential growth followed by a sudden collapse. A boom and
bust curve usually shows an insect population’s cycles through the
year. They are abundant in the summer months but are limited in
the fall and winter months.