Essential Questions
What are the factors
that affect
population growth?
What are some of the
effects that
overpopulation can
have on an
environment?
http://en.wikipedia.org/wiki/Paul_R._Ehrlich#mediaviewer/File:2008_Summer_Olympics_torch_relay,_Shenzen.jpg
Steve Jerveston
CC BY 2.0
one
smallest
group
individual
of unit
organs
of
living
living
all
organisms
interacting
similar
different
of
cells
the
living
and
large
region
with
things
working
thing
organized
kinds
same
populations
kind
of together
tissues
to
living
inwork
anin
nonliving
things
characteristic
plants
together
working
one
ecosystem
together
interacting
within
and area
animals
that a
certain
includesarea
several
ecosystems
cell
Populations in Ecosystems
Vocabulary
• Abiotic Factors – Non-living
components of an area (rocks,
weather, sunlight, etc.).
• Biotic Factors – Living organisms as
well as the products of living
organisms.
• Carrying Capacity – The maximum size
of a population that can be sustained
by any given ecosystem.
• Ecosystem – Living and non-living
factors interacting within a specific
area.
• Organism – A living thing.
Populations in Ecosystems
Vocabulary
• Environment – The area around an
organism including living and
nonliving things.
• Limiting Factor – Any biotic or abiotic
factor that controls population size.
• Population – All of the interacting
individuals of one species in a given
area.
• Birth Rate – Number of individuals
born per 1000 individuals in a
population.
• Death Rate – Number of individuals
that died per 1000 individuals in a
population.
How populations change in size over
time – four major factors
Birth Rate:
Death Rate
Immigration:
(number of live
births per 1000
individuals)
(number of
deaths per 1000
individuals)
(movement into
an area)
Emigration:
(movement out
of an area)
How can
How can
How can the
How can the
immigration
emigration affect
birth rate affect death rate affect affect population
population size?
population size? population size?
size?
Population Size
What goes up must come down
•Increases in population: through birth
or immigration
•Decreases in population: through
death or emigration.
Change in
Population
=
Can you think of something in nature that exhibits
exponential growth? Logistic growth?
Populations will follow
two general paths:
“Boom and Bust”
• When faced with
unlimited resources,
it will grow
exponentially.
• When faced with
limited resources, it
will grow logistically.
https://www.boundless.com/biology/population-and-community-ecology/environmental-limits-to-populationgrowth/exponential-growth/
CC By 3.0
“Boom then Stable”
Can you think of some resources that could limit population growth?
Characterize these resources as abiotic or biotic.
• Populations grow rapidly with ample resources (biotic
potential), but as resources become limited (environmental
resistance), population growth rate slows and levels off.
• Carrying Capacity (K) is the maximum number of organisms
that an area can support for longer lengths of time.
Exponential and Logistic Population
Growth: J-Curves and S-Curves
• As a population levels off, it often
fluctuates slightly above and below the
carrying capacity.
By the year 2020, 9 to 10 billion humans are
expected to inhabit the planet. Do you think the
world is overpopulated?
Check out the link below for a
great video on the topic!
http://overpopulationisamyth.com/