# Changes to Populations

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On your desk you should only have a…
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Pencil
Four Papers to be checked in this order on a pile
on the top of your desk.
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Mark Return Recapture Lab
Carrying Capacity Lab
Mini Webquest Note Sheet
Carrying Capacity Worksheet
I will check these during your quiz
Changes to Populations
4 factors that effect the size of a
population
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Increase Population
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Decrease Population
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1) Birth
2) Immigration (entering a population)
3) Death
4) Emigration (leaving a population)
See if you can create an equation using these 4
terms for Population Growth, Population
Decrease, Population Stability
Is the population increasing or
decreasing?
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Populations Increase:
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Population Remains Stable:
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When Immigration + Births &gt; Death + Emigration
When Immigration + Births = Death + Emigration:
Populations Decrease:
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When Immigration + Births &lt; Death + Emigration
What are Limiting Factors?
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Anything that
prevents the
growth of a
population
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What would
happen without
limiting factors?
Carrying Capacity (k)

The
maximum
population a
species can
maintain in a
certain area
without
damaging the
ecosystem.
Population can stabilize at K
What happens when a population
goes above carrying capacity?
Populations can crash if #s go
above K
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29 introduced in
1944
More than 6,000
by 1963
Down to 42
Seasonal Fluctuations
What will happen with World
Population?
Everybody Out of Their Seats
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Go to the back of the room…
You are all the population of deer in PA.
Lets progress through the year, and test the
effects of limiting factors on a population.
Ideally we will have 5 deer at the end of the
year before breeding.
Limiting Factor #1:
Space
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Territorial
Animals need
a large amount
of space.
Loss of Habitat
causes the
decline of
many species.
Who took my towel?
Loss of Space/Habitat Example:
Bluebirds
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Loss of trees/wooden posts caused a huge
decline
Between 1935-1985 numbers declined by 90%
Limiting Factor #2
Food and Water
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dehydration,
starvation
Some animals will
emigrate
Organisms that rely
on one type of food
are severely
affected
Food and Water Example:
Snowshoe Hare and Lynx
Limiting Factor #3:
Climate and Weather
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Temperature
changes can
affect plants
and animals
Floods and
storms can
cause death
&amp; destruction
of habitat
Climate Changes Example:
Mosquito Populations
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Mosquitoes
breed in
standing
water
Rainfall
creates
puddles of
standing
water
Temperature Changes:
Coffee Habitat
Impact of Temperature
Rise on Robusta Coffee
in Uganda.
*Developing countries,
whose economies often
rely heavily on one or two
agricultural products, are
especially vulnerable to
climate change.
*This graphic shows that
With an increase of only
2 degrees Celsius, there
would be a dramatic
decrease in the amount
of land suitable for
growing Robusta coffee
in Uganda.
Limiting Factor #4:
Cover
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Protection
from
predators
Protection
from
weather
Cover Example:
Ruffed Grouse
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Ruffed Grouse- Requires
brushy forests for cover and
food. Most of Pa’s forest were
logged (cut down) 80 to 100
years ago. They grew into
brushy forest allowing grouse
populations to increase.
Forests are now maturing
reducing cover and food
causing populations to decline.
Land development has also
reduced populations
Limiting Factor #5:
Increase Predation
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An increase in the number of predators to an
area will impact prey species.
Predation Example:
House Cats!
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Predicted that in one
year house cats kill 1
billion songbirds!
Limiting Factor #6:
Disease
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
populations
Can devastate populations with low genetic
diversity
Disease:
West Nile Virus
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Mosquito
born
disease
5,697 crows
reported
NYS in
1999
White Nose Syndrome
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Fungus that has killed over one million bats
90-100% of some species of hibernating bats
are in danger of being killed.
Limiting Factor #7:
Light
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Plants that cannot tolerate too much or too
little light can be affected
Light Example:
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Aspen Pine Poplar = intolerant,
will dominate young forests
Beech, Fir, Hemlock, Maple =
tolerant will dominate older forests
Limiting Factor #8:
Human Presence
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Close
proximity to
humans
causes some
species to
emigrate
Other species
thrive
Reflection
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Think of an example where an organism does
not have enough limiting factors.
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What is the organism, how does this affect the
habitat around that organism?
Changes in Population
Competition
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Limiting factors lead to competition among
organisms for available resources
A loss in a limiting factor can contribute to a
decline in populations
Increased due to exotic species
Exotic Species- Introduced species not native or
endemic to the area in question.
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