The document discusses natural selection and how traits become more or less common over generations within populations. It describes an investigation using a simulation of ostrilopes with different color traits. Data was collected on how many offspring each color trait produced. The data showed that ostrilopes with the yellow color 7 trait reproduced more on average and became more common in the population over time, while ostrilopes with traits like blue 1 and yellow 10 that did not provide camouflage reproduced less and became less common. This occurred because traits that helped ostrilopes survive longer, like yellow 7, allowed them to reproduce more and pass on their genes more frequently.

1. CHAPTER 2 – NATURAL SELECTION
AND REPRODUCTION

2. 2.2.1:WARM-UP
We agree that the newt population became more poisonous because the snakes in this
environment caused poison to be an adaptive trait. Now, we will add to this claim.
The claim additions below are ideas from park visitors about how the newts got so poisonous.
Based on what you have learned so far, decide which additions you think are true, false, or
partially true. Read each claim and select from the choices in the dropdown menu.
1. Poison Level 10 is the most common because the newts with this trait were
able to live longer than other newts.
2. Poison Level 10 is the most common because the newts with this trait
reproduce more than other newts.

3. 2.2.1:WARM-UP
We now have to consider two competing ideas.
Some park visitors have suggested that Poison Level 10 is the
most common because newts with this trait live longer than
other newts.
Others think that Poison Level 10 is the most common
because newts with this trait reproduce more than other
newts.
Each of these ideas builds on the claim we decided to support
at the end of Chapter 1, but now we need to figure out which
one is best supported by evidence.

4. Observe individual ostrilopes with different traits to see a relationship between traits and the
amount of reproduction.
Key concept
Individuals inherit their genes from
their parents, and these genes
determine their traits.
Therefore, traits in a population are
passed down from generation to
generation.
2.2.2: SIM
OBSERVING REPRODUCTION IN THE SIM
Investigation Question
How do some traits become more
common over many generations
while others become less common?

5. Some organisms reproduce more than
others.
Let’s review possible answers to the Investigation
Question.
• Some organisms can have more offspring than
others.
• Some organisms will not survive in the
environment long enough to reproduce.
If yellow ostrilopes from one generation had
more offspring than green ostrilopes, would the
next generation have more yellow ostrilopes
than green ostrilopes?
2.2.2: SIM
OBSERVING REPRODUCTION IN THE SIM
YES

6. 2.2.2: SIM
OBSERVING REPRODUCTION IN THE SIM
Using the Reproduction Claims mode let’s zoom in and demonstrate locating an ostrilope
with a color trait from the data table on your screen (Blue 1, Blue 4,Yellow 7,Yellow 10).
Let’s Project the Natural Selection Simulation and demonstrate collecting data
and resetting the Sim.

7. 2.2.2: SIM
OBSERVING REPRODUCTION IN THE SIM
Select that ostrilope and press RUN.
Count the number of times that ostrilope reproduces, and demonstrate recording that
number in the data table.Then demonstrate resetting the Sim to collect data for a different
ostrilope color.
Let’s Project the Natural Selection Simulation and demonstrate collecting data
and resetting the Sim.
Record the number of
times the ostrilope
Reproduces
Reset SIM after each ostrilope dies.

8. 2.2.2: SIM
OBSERVING REPRODUCTION IN THE SIM

9. 2.2.2: SIM
OBSERVING REPRODUCTION IN THE SIM
We gathered information about the number
of offspring for each color trait in the data
table.
But, following just a few ostrilopes before
they die is not enough for us to identify a
pattern at the scale of the population.
To do this, we need to compare
observations from the whole class and
come to a group conclusion about what we
see.
We’ll need to collect data from each group
and average it.
Collecting whole class data using the DATATOOL

10. 2.2.2: SIM
OBSERVING REPRODUCTION IN THE SIM
Let’s share what you notice from the
data tool
Observe the following:
• Not all ostrilopes reproduced the same
amount.
• Ostrilopes with adaptive traits (Yellow
Color 7) reproduced more on average
(because they were the most likely to
survive).
• Ostrilopes with non-adaptive traits
(Levels 1, 4, and 10) reproduced less on
average (because they were less likely to
survive as long).

11. 2.2.2: SIM
OBSERVING REPRODUCTION IN THE SIM
Discuss with your table how this averaged data from the class helps to answer the
Investigation Question

12. 2.2.2: SIM
OBSERVING REPRODUCTION IN THE SIM
1. What pattern describes the relationship between how long an ostrilope lived and how many offspring it had?
2. Which ostrilopes became more common over time, and why?
3. Which ostrilopes became less common over time, and why?
4. If the color of the environment became blue, which ostrilopes do you think would become more or less
common, and why?
Ostrilopes that lived longer had more offspring.
Ostrilopes withYellow Color 7 became more common because they survived longer, so they had more
opportunities to reproduce and have offspring.
Ostrilopes with colors that didn’t blend into the environment, like Blue Color 1, 4, andYellow Color 10, became less
common because they were more likely to be eaten by predators before they could have many offspring.
Ostrilopes with blue-color traits would become more common because they’d be camouflaged and survive longer, so
they could have more offspring. Ostrilopes with green and yellow colors would be more likely to be eaten by
carnithons before they could have many offspring.

13. 2.2.2: SIM
OBSERVING REPRODUCTION IN THE SIM
Answer the poll by selecting your choice at the bottom of .
Supports: ostrilopes with Yellow Color 7
had a higher average then the others.
VIEW POLLING DATA

14. 2.2.3: MODELING TOOL
RESPONDING TO SHERMAN
You will create a model to explain how different organisms’ survival and
reproduction rates lead to traits becoming more or less common over time.GOAL
You will be using the Modeling Tool
to respond to Sherman.
Scientists often explain their
thinking in writing and by making
visual models.
You are going to return to
the Sherman’s Story from the
previous lesson and explain your
thinking by writing a response and
making a visual model.

15. 2.2.3: MODELING TOOL
RESPONDING TO SHERMAN
NEW TRAIT
LABELS
You will make a
model of how the
distribution of beak-
strength traits
changed.
This model will help
you write your
responses to
Sherman.
You can add more
than one Trait label
to a single trait.
Add trait
labels
Predict
Histogram

16. 2.2.3: MODELING TOOL
RESPONDING TO SHERMAN
Respond to Prompt after creating
your visual model.
1 2
3

17. 2.2.3: MODELING TOOL
RESPONDING TO SHERMAN
ModelingTool Response:
A proficient model is shown below. You should group theTrait labels together as shown in Histogram 1 (+S
with +O, -S with -O). Proficient models should include at least two traits labeled in Histogram 1 but might
include all traits labeled. Predictions about Histogram 2 will vary significantly. Correct responses should show a
shift in distribution of traits toward stronger beak strength and should only include traits that were present in
Histogram 1.
TIME

18. 2.2.3: MODELING TOOL
RESPONDING TO SHERMAN
WHY DOTHESE BIRDS HAVE STRONGER BEAKS
TIME
Individuals get their traits from their parents.
The birds with stronger beaks
were able to crack open more
seeds and eat more, which
means they lived longer and
reproduced more, passing on
their strong-beak trait.
What may have happened is birds with weak beaks couldn’t crack enough seeds to have enough to eat to survive,
and so they died before they could reproduce, which means they did not pass on their weak-beak trait.
Over many generations, the
distribution of traits changed
so that the population had
more and more individuals
with the strong-beak trait.

19. 2.2.3: MODELING TOOL
RESPONDING TO SHERMAN
Let’s share your responses to Sherman’s Story.
Connecting Sherman’s Story to the old claim that individual newts became more
poisonous because they wanted to.
In the Warm-Up, you read and thought about the claims regarding the newt mystery.
Based on Sherman’s Story that you just read, what else can we say to people who
think that the newts in Oregon State Park became more poisonous because they
wanted to?
That’s impossible. Traits are determined by genes that are
inherited from an individual’s parents. Individuals cannot
choose their traits.

20. 2.1.4 HOMEWORK
MAKING CONNECTIONS
Example:
• We have been investigating how populations change over many generations.
• Most of these changes are in response to environmental changes.
• This is connected to what you learned about in the Microbiome unit.
• When one part of the body system changes, such as an increase in the number of harmful gut
bacteria, other body systems are affected.
• As a result, the other helpful bacteria in the intestines cannot survive, which makes people sick.
Think creatively!
Challenge yourself to connect a very
different science topic to our current topic.