2. 2.1.1: WARM-UP
You just identified the ideas
you already have about how
individuals with adaptive traits
can become so much more
common in a population.
Making note of the ideas we
already have, gathering more
evidence, and then deciding if
our ideas should change or not
based on that evidence are
important practices that
scientists use all the time.
3. 2.1.1: WARM-UP
Chapter 2 Question:
How did the trait for
increased poison level
become more common in
the newt population?
4. 2.1.1: WARM-UP
Sherman thinks that the birds got
the adaptive trait for stronger
beaks because the parent birds
all had offspring with stronger
beaks so the offspring would
survive.
We are wondering about a similar
idea—there are a lot more newts
with high-poison levels now
compared to 50 generations ago.
How did the trait for increased
poison level become more
common in the newt population?
5. 2.1.1: WARM-UP
To help answer the Chapter 2
Question, we will start by
investigating the question:
How do individuals in a
population get their traits?
If Sherman is right, then
reproduction should produce
offspring with adaptive traits.
We can test that in the Sim.
6. 2.1.2: REPRODUCTION IN THE SIM
Students use the Sim to gather evidence about whether or not reproduction always results in
offspring with adaptive traits. (15 min)
Lets Discus
This!
Which trait for color ostrilopes will be
adaptive in the Sim environment?
7. 2.1.2: REPRODUCTION IN THE SIM
• Open the Natural
Selection Sim and
launch the Reproduction
Claims mode.
• Press RUN.
• As the Simulation runs,
zoom in to review the
following aspects of the
Sim for gathering
evidence:
8. 2.1.2: REPRODUCTION IN THE SIM
Following an individual ostrilope:
Selecting an ostrilope will allow you to follow
one individual around.
This is noted by the blue circle on the ground
surrounding the ostrilope.
Investigating trait values:
Selecting an ostrilope also allows you to read
its specific trait values in the window on the
left side of the screen.
This is where you can find out which color
level an ostrilope has, such as Green Color 5.
9. 2.1.2: REPRODUCTION IN THE SIM
Finding ostrilopes that are about to
reproduce:
Make note of two ways to tell if an
ostrilope is about to mate—
1. the status line in the organism data
window about an individual ostrilope
2. the bouncing walk they use on their
way toward each other.
Slowing down and pausing the Sim:
Use the time control dropdown (x.05,
x1, x4) to slow down the Sim to half
speed, or pause the Sim to make it
easier to gather data about individual
ostrilopes immediately after
reproduction.
13. 2.1.2: REPRODUCTION IN THE SIM
Project and run
the Natural
Selection Sim
mode: Reproduction
Claims to gather
approximately 10
generations of data.
Then press ANALYZE
to show the Ostrilope
Color Histogram,
focusing on how
reproduction affects
traits at the
population level.
14. 2.1.2: REPRODUCTION IN THE SIM
Move the Generations
slider all the way to
the left to show the
Starting Population
Histogram.
Describe the color
traits present in the
starting population.
15. 2.1.2: REPRODUCTION IN THE SIM
Are there any traits in
the ostrilope offspring
that were new to the
population?
No, all of the traits in
the offspring were
present in the original
population; these
traits were passed
down from ostrilopes
in the starting
population.
16. 2.1.2: REPRODUCTION IN THE SIM
Blue and green traits
became less common.
QUESTION: Will
individuals with those
non-adaptive traits
have any offspring with
adaptive traits (Yellow
Color 7)?
No, traits are passed
from parents to
offspring.
17. 2.1.2: REPRODUCTION IN THE SIM
Evidence:
1. Some offspring produced had adaptive trait (Yellow 7) with adaptive
trait in parent
2. Some offspring did not produce adaptive trait (Yellow 7) with adaptive
trait in parent
3. All traits in initial population were passed on through 10th generation
18. 2.1.2: REPRODUCTION IN THE SIM
Refuted, because non-adaptive traits were
passed on just like adaptive traits were
passed on.
19. 2.1.3: TRAITS OVER GENERATIONS
We used the Sim to gather evidence to refute the
claim that reproduction always produces offspring
with adaptive traits. We saw that this claim wasn’t
true because in a population the traits of offspring
are generally similar to the traits of their parents.
But, reproduction does play a key role in how the
distribution of traits in a population changes over
time. In this activity, we will model how trait
distribution in populations change with each round
of offspring in a new generation.
20. Remember, this is only a model of how
inheritance works, so some details about
inheritance have been simplified so we
can look at how reproduction affects
traits at the population level. In reality,
offspring are not exact replicas of their
parents. We know that from looking at
real-life examples of parents and
offspring.
2.1.3: TRAITS OVER GENERATIONS
You may remember from when you learned about
the inheritance of traits that if some of the cubes
represented heterozygous individuals (individuals
who have gene versions that are different) they
could produce offspring with traits that are different
from both parents. That’s why sometimes two
brown-eyed parents have a blue-eyed child. In
general, the traits of offspring will be more similar to
their parents than to other, less-closely-related
members of the population.
