Sponge: Set up Cornell Notes on pg. 15
Topic: 5.3 Populations
Essential Question: Two centuries ago,
there were only one billion people on Earth.
Today, over 6 billion. Which phase of the scurve are we in?
5.3 Populations
Two centuries ago, there were only one billion people
on Earth. Today, over 6 billion. Which phase of the scurve are we in?
Key Vocabulary:
Natality
Mortality
Immigration
Emigration
BIOZONE: None
BIOZONE: None
LAB REPORT DUE FRIDAY!!!!
S-shaped curve
Exponential phase
Transitional Phase
Plateau Phase
Carrying Capacity
P. 14
Natality
Immigration
S-shaped Curve
Mortality
Emigration
Mt. St. Helens Clip
6m30s
• https://www.youtube.com/watch?v=-H_HZVY1tT4
Mount Saint Helens Eruption 1980
• Little was left of the forest and rivers
• Trees were knocked over
• Fires/gases/Volcanic Ash burned everything
• Even though the mountain was evacuated, some people who did not
leave in time perished
• Within months, LIFE WAS BACK
• Within a couple of decades… a grassland ecosystem has reappeared
Population Growth Curve
• After an event that wipes out most life (Mt. St. Helens), there can be
a dramatic increase in population #s
• Eventually a complete forest will grow again, and all habitats will be
occupied
• The numbers of organisms will stabilize and not get any bigger
Assessment Statement
• 5.3.1 Outline how population size is affected by natality,
immigration, mortality, and emigration.
4 main factors affect population size
• 1. Natality- the # of new members of the species due to reproduction
• 2. Mortality- the # of deaths
Draw pictures that represent each
P. 14
• 3. Immigration- members arriving from other places
• 4. Emigration- members leaving the population
Draw pictures that represent each
P. 14
Assessment Statement
• 5.3.4 List three factors that set limits to population increase
Carrying Capacity
• The maximum # of individuals that a particular habitat can support
is called the carrying capacity
• No habitat can accommodate an unlimited number of organisms
White Boards!!! Get Your Whiteboards!!!!
• What are some factors that would LIMIT the
carrying capacity of a habitat?
Limiting Factors
• Availability of resources:
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•
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water
food
sunlight
shelter
space
oxygen
• Build up of waste such as excrement or excess CO2
• Predation
• Disease
Bottom ½ of p. 15
Exponential
Growth Phase
S-shaped Curve
Transitional
Phase
Plateau
Phase
Assessment Statement
• 5.3.2 Draw and label a graph showing a sigmoid (Sshaped) population growth curve
• 5.3.3 Explain the reasons for the exponential growth phase,
the plateau phase and the transitional phase between
these two phases
The Sigmoid (s-Shaped) Curve
The Sigmoid (s-Shaped) Curve
• 1. Exponential Growth Phase (logarithmic phase): the numbers of
individuals increases at a faster and faster rate
• 2. Transitional phase: the growth rate slows down considerably- the
population is still increasing but at a slower and slower rate
• 3. The Plateau Phase (Stationary phase): the number of individuals
has stabilized- there is no more growth
Exponential Phase
• In ideal conditions, a population can double on a regular basis (not
counting mortality)
• Without predators, an introduced species can take over habitats with
uncontrolled population growth
• Why? (Whiteboards)
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•
•
•
Plentiful resources (space/food/light)
Little or no competition
Favorable abiotic factors (temp/oxy levels)
Little or no predation or disease
Transitional Phase
• What will begin to happen as growth rate continues to increase?
• Eventually, some of the previously listed factors above will no longer
be true
• As population number increases, competition increases
• Predators will be attracted to a growing food supply and move in
• As numbers increase, and crowding occur, diseases begin to spread
Plateau Phase
• Once all the fertile ground is covered with plants the space available
will be occupied to its maximum (less available room for seeds)
• With increasing #s of herbivores, there will be a limited supply of food (in
response animals have less offspring)
• Predators and disease increase mortality rate
• Growth curve tends to level off
• Births + Immigration = Deaths + Emigration
s-Shaped Curve
Carrying Capacity
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Draw on the
bottom of
P. 14
Population Biology
• The Effect of Predators on Prey Populations
Too Many Deer
Sponge: Set up Cornell Notes on pg. 17
G1/G3/5.3 Estimating Populations
Topic: G1/G3/5.3 Estimating Populations
Essential Question:
BIOZONE: 232-235
LAB REPORT DUE TOMORROW!!!!
BRING BIOZONES ON
MONDAY
Key Vocabulary:
Random Sampling
Quadrat Method
Transect Technique
Capture-Mark-Release-Recapture Method
BIOZONE: 232-235
Assessment Statement
• G.1.3 Describe one method of random sampling, based on
quadrat methods, that is used to compare the population
size of two plant or two animal species
Random Sampling
• How can we determine population numbers?
• We could go count every pine tree in a forest, but that would be too time
consuming
• Ecologists instead use a sampling method
• They take a “random sample” and use it to estimate the total number
of organisms
• Samples should come from all around the habitat
Quadrat Method
• The quadrat is a square of a certain size
• Organisms within the quadrat are counted and these counts are
used to determine the population size of a given area
• They can be small or large depending on what you are counting
Method Summary
• Map an entire area of the tide pools
• Determine the size of the quadrats
• Place a grid with numbers over the map of the tide pool
area
• Choose which squares to sample using a random number
table
• Count the number of starfish in each sample quadrat
• Calculate the average # of starfish in your sample
quadrats
• Multiply the average by the total number of quadrats on
your map to get an estimate of the total number of
starfish in the tide pools
Assessment Statement
• G.1.4 Outline the use of a transect to correlate the
distribution of plant or animal species with an abiotic
variable
The Transect Technique
• Commonly used for studying how the distribution of plants in an
ecosystem is affected by abiotic factors
• At right angles, lay tape all the way around your chosen ecosystem
• Every 10-20 meters along the tape, mark out a quadrat always using the same
size
• Identify and count the plant species of interest in each quadrat
• Measure the abiotic feature that you have chosen in each quadrat
(temp/light/soil pH/water/mineral nutrients)
• You can now determine the pattern of distribution of plant species from
different areas of the ecosystem and see if it correlates with the abiotic
factor you chose
Quadrat Activity: How Many Sunflowers in a
Meadow?
LAB REPORTS DUE
• Make sure your name/period # is clearly written
• Stapled?
• PLEASE ATTACH DATA COLLECTION SHEET!!!!
Assessment Statement
• G.5.3 Describe one technique used to estimate the
population size of an animal species based on a markrelease-recapture method
Capture-Mark-Release-Recapture Method
• Allows you to estimate the # of animals in an ecosystem
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Catch some of the population
Mark them, and release them back into the wild
A second sample of the population is captured
Some will be marked, some will be unmarked
• The thought: the proportion of marked to unmarked individuals in the
second sample is the same as the proportion of the originally marked
individuals to the whole population
# marked in the 2nd sample (n3) = # marked in the 1st sample (n1)
total # caught in 2nd sample (n2)
size of the whole population
Capture-Mark-Release-Recapture Limitations
• Marks may injure animals
• Marks may make animals more visible to predators
• Method assumes there is no immigration/emigration
• Let’s try it!!!!