Population Studies

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Transcript Population Studies

Things you will need for today:
The two papers in the front of the room (top shelf)
Home Work:
Write a one paragraph letter home explaining why we
need to
keep a close eye on our resources. You should
use key terms such as: J-Curve, Boom-and-Bust Curve,
Carrying Capacity, and Resources
environmental issue is causing this!?
Warm Up What
Explain your thoughts
Fracking Sites
Emerald Ash Borer
Population Studies
Population Studies
Population- a group of individuals of a single species
inhabiting a specific area
Why study populations?
– Too high or low populations = unstable ecosystem
– Low species diversity = unstable ecosystem
 Endangered Species = low population due to human
Invasive Species = human introduction of a new
species to an ecosystem with no predators or
competition allowing the population to increase rapidly
Examples of Invasive Species
European Gypsy Moth
Introduced from Europe in 1869
They were imported for silk
They defoliate sections of forest
Brown Marmorated Stink Bug
Native to Eastern Asia
1st found in Allentown, PA in 1998
Possibly arrived in shipping crates from
They feed on a variety of plants,
including fruit trees, ornamental trees
and shrubs, and some crops
Currently found in the northeast, midAtlantic region and the Pacific northwest
What keeps populations
from growing out of control?
Limiting factors- A biotic or abiotic
factor that a population needs as a
resource to exist.
– Provide Examples:
Carrying capacity- the number of
individuals an ecosystem can support.
 When the birth rate exceeds the death rate.
Resources (food, shelter, water,
etc) are abundant enough that the
population of a species can increase
Population Graphs
J curve- exponential growth of a population
because of no natural predators and an
abundance of resources.
(Usually followed by a crash in population after
it exceeds the carrying capacity).
Population Graphs
S curve- a population increases to its carrying
capacity and levels off being kept in check by
natural predators
7. Billion
World’s population as of 6/4/13
at 4:22 pm 7,089,652,886
Human Population
World population didn’t hit 1 Billion until
around 1850.
World’s Estimated Current Population (US
Census Burrow)
Population Study Example
What kind of relationship does the graph show?
Which population seems to increase first before it drops?
Is the hare and lynx relationship a density dependent or
density independent limiting factor?
How do ecologists
determine population?
Counting- count the number in the
 Mark and Recapture- ex: bird
banding, tagging, microchips
 Random sampling- look at a part of
the ecosystem and assume it is the
same for the whole ecosystem
Which is the best
method to determine
each population?
Trout in the Delaware River
 Diversity of trees in a state park
 Eagle eggs in a nest
 Deer in Bucks County
 Dandelions in my neighbors yard
 Trees on the school property
Random Sampling Method
Choose letter and number combinations
 A-J and 1-10
Count the number of dots in each letter
and number combination square that you
chose and place the numbers in the chart
When finished, add up these numbers for
the total in the sample
Find the estimated total and then find the
actual total
How well did this method work?
Table Set-up for Random Sampling
# of sunflower
Ex: G3
Total # of
in 10
Total # of
in meadow=
(Total/10) x
Count actual
# of
in meadow
Mark & Recapture Method
Plug your numbers into the following
equation for each trial. Solve for P.
P = A (B/R)
P = estimated population
A = # caught and marked the first time
B = # caught the second time
R = # caught 2nd time which were marked
Mark and Recapture
Choose a color (L yellow, D yellow, orange,
purple, pink, L blue, L green, D green, red)
Count how many beads in your bowl are
your color then release them back into the
bowl. This number=A
 A = # caught & marked during the first catch
Grab a small cup full and count the total
number of beads in your hand. This
number = B
 B = # caught during the 2nd catch)
Count how many are your color in your
hand. This number = R
 R = # caught during 2nd catch that were already
(If Time) Repeat this method for 5 trials an
record results
Table for Mark & Recapture Method
Trial 1 Trial 2 Trial 3 Trial 4 Trial 5
For Home Work
Write a one paragraph letter home
explaining why we need to keep a
close eye on our resources. They
should use key terms such as JCurve, Boom-and-Bust Curve,
Carrying Capacity, and Resources