(calming music)
- What's up Seattle and Denver?
Welcome back for Natural Selection Part 3,
covering lessons 1.5 and 1.6.
I'm Miss Annie Jarnagan,
just like Miss Elasky,
I teach at Asa Mercer
International Middle School
in Seattle Washington,
and I'm bringing you
today's lovely learning
from my fortress of science.
And as a quick introduction,
that right there,
that's my cat, Kitty, not a creative name,
probably won't see her on cam,
but you will hear her wrestling
around in the background.
So what you'll need for this
lesson is a pen or pencil,
some lined or blank pieces of paper,
and optional but
encouraged, a family member
or friend you can check in with,
a copy of the Ostrilope
and Thornpalm histograms,
a copy of, "Explaining Changes
in the Newt Population",
and a copy of, "Writing About
the Rough-Skinned Newts".
Also awesome if there's a
computer logged in to Amplify.
So, let's go ahead and get
into our lesson for today,
this is, "Natural Selection,
1.5: Adaptive Traits".
So, go ahead and take
a look at the histogram
on the left about the Rough-Skinned Newts,
50 generations ago and today,
looking at the trait poison level.
Now, this would be a great time to pause
and talk with your friend,
family or even to yourself.
"How would you describe
the distribution of traits
"in the population 50 generations ago?"
How would you describe
the population today?
And, "How has the rough-skinned
newt population changed?"
So, go ahead an pause now.
So, when I look at this
histogram for 50 generations ago,
what I notice is,
it started off with a
lot and a lot of newts,
with a roughly low poison amount.
But when we look at the population today,
it looks like it's almost
entirely high poison
and interestingly enough,
I'm not seeing any more
of these low poison newts.
So, one way to describe
what happened between
50 generations ago to today would be
there are more high poison
and less low poison newts
today than 50 generations ago.
So, today we're gonna be considering a lot
about adaptive traits and
the impact to environment,
but let's first stop
and think for a moment
about something called camouflage,
and how it can help an organism
to survive in its environment.
So, camouflage is an
adaptive trait that helps
an organism to survive by hiding
and blending into its background.
A really common example in
biology is the pepper moths.
Maybe a little hard to see
but we have a pepper
moth living right here
and another one over here,
that both have colors and patterns
that match to their
backgrounds really well.
How this is adaptive
is that if an organism
is able to hide in its environment,
it either gains an advantage
from hiding away from predators
or an advantage in hunting
down its own food sources.
Be considering in the Sim
today is, "Yellow color
"is always an adaptive trait
in a yellow environment".
Just like this ostrilope right here
living in a yellow environment.
So, agree?
Disagree?
Let's look into some
information and find out.
To test this idea about adaptive traits,
we're gonna take the same
population of ostrilopes
and put them into two
different situations.
The first one's gonna be Environment A,
where we'll have the yellow 7 background
and we'll have predators
called carnithons.
Environment B will be the
same yellow 7 background,
but there will be no predators,
no carnithons at all.
To understand the impact of
the environment on a trait
let's start by looking at
the starting histogram
for these populations.
What I can notice here in this histogram
is the starting population
has actually a pretty
large variation of traits,
ranging all the way from blue
colors to greens and yellows.
But there's actually no
yellow number 10 here,
so we're probably not
gonna see them come up.
If you have access to Amplify at home,
right now would be a good moment to pause,
go to Tab 2, "Investigating
Adaptive Traits in the Sim",
and try out page 2 and
3 for this activity.
I'm in here in the Sim
and I'm doing Environment A.
I already set the background
color to yellow 7,
and I'm gonna leave
the little red predators,
carnithons, left on.
And I'm also just gonna zoom in for fun
and find a yellow 7 individual,
so we can just see what they do.
So, hit and run, and
put it on fast forward.
All right, well run around, having babies,
eating, his friends are getting eaten,
like that blue one, and that one.
Well he's doing all right,
opp nope, there he goes.
Okay, well, let's kind of
think about what happens
after 50 generations, but one
thing I can at least tell,
he wasn't getting eaten
as much as the blue
or the green ostrilopes that we saw.
So, if you're working through paper,
now is a good time to
pause, take out your paper,
copy down this histogram or
go to page 5 in your packet.
Okay, now write or discuss.
Does the evidence you see
here support or refute
the idea that yellow 7 is always adaptive
in a yellow 7 environment?
Just remember, this
histogram here is population
and environment A in a yellow environment
that does have predators.
Okay, now that you've
had a moment to discuss,
let's go ahead and stop for a
sec and look at Environment B,
when there are no predators involved.
Well, I'm back in here for the Sim,
I've set it for that yellow 7 environment,
but I'm gonna remove all of the carnithons
and why don't we have fun
and just track a yellow
7 for a little bit.
So, I put on fast-forward,
I'm just kind of watching
and honestly it seems
like everybody's fine.
I mean last time I saw carnithons eating
all of the blues and the greens.
And right now it doesn't really
seem like it matters, Hmm.
So, a good moment to
pause, this is a histogram
I got for environment B
when there weren't any predators involved.
Go ahead and either copy that down
or take a look at it in your packet.
And once you have this down, pause a sec
and either write or discuss,
does this evidence support
or refute the idea that being yellow
is always adaptive in
a yellow environment?
Now that you've had the
time to think that over,
big question here.
What's happening in the populations
for both of the environments
and how does this overall support
or refute the claim that being yellow
is always adaptive to
a yellow environment?
Go and just talk that out.
Let's just spend a quick
second analyzing the histogram
and the situation when
there were predators.
What I'm noticing here
is that it's really only
this yellow 7 trait that
survived with the carnithons.
Every other trait just disappeared
and like I noticed when
I was watching the sim,
all of the blues and greens
and actually some of the
yellows still died, Hmm.
So, what it seems is, since
only this yellow 7 survived
in that environment, seems to me like yes.
This actually seems to
support our thinking
that being yellow is always adaptive.
Now, let's look at environment B.
Looking at the environment B histogram,
what I can notice here is
that, kind of oddly actually,
yellow 7 completely disappeared.
Even though it matched the background.
And it seems like actually
the blues, the greens,
they were doing pretty okay,
like we noticed when we ran the sim.
So, thinking about this
it doesn't seem like
being yellow 7 in a yellow
environment does anything here.
I would say this evidence
actually very well refutes
the idea that being yellow
in a yellow environment
is always helpful or adaptive.
So, when we think over the
overall why this happens,
well what happens is that if
a trait's adaptive or not,
really depends on the environment.
If you're in a situation
where something's attempting to eat you,
your ability to hide is actually
a pretty adaptive trait.
You're not getting your face eaten off,
you survive to live another day.
Have offspring, pass on your traits.
But, but, if there isn't
something like a predator
in your environment trying
to hunt you down and eat you,
it doesn't really matter
if you're camouflaged at that point.
And that's what we're seeing here is
it didn't matter in the end.
So no, actually being yellow
would not always be adaptive
to a yellow environment.
There would have to be
something like a predator
that would give that advantage.
So, that brings us to a key concept.
Key concept.
Over many generations,
individuals with adaptive traits
become more common in a population,
while individuals with non-adaptive traits
become less common.
Go ahead and pause and write this down.
All right, and our,
this is kinda second key concept to that.
Whether or not a trait is adaptive
depends on the environment.
And it's worth repeating here,
environment is all of the
abiotic or non-living things,
and all the biotic things
or the living things in
an organism's environment.
Okay, for this next activity
we're gonna be making a prediction.
A prediction is an idea
about what might happen
that's based on what you already know.
We're going to be predicting
is water storage traits
in Thornpalms, a plant.
And we're gonna think about how high
water storage in a thornpalm population
can become more common over time.
When we look at this in the Sim,
thornpalms that are thinner like this
will be low water storage,
the medium water storage,
and then the ones with the broad base
will be high water storage.
So, let's think about
plants and water storage.
What water storage is for a plant
is how well a plant can
keep water to use later.
A good example of a
high water storage plant
would be a cactus.
When it's raining, the
cactus stores up water
into its body for later use,
so that when it's not raining
the cactus is still going
to be able to survive
because they have water that
they stored up from earlier.
High water storage is
actually an adaptive trait
seen in many, many plants.
Make your prediction now,
based on what we know
about water storage in plants
and the information that
we can see in the histogram
from the starting population.
And what we're gonna think about is
predicting how and why
traits for increased levels
of water storage can become more common
in a thornpalm population.
So go ahead, pause now.
If you have access to
Amplify, go to lesson 1.5
and click on 3, modeling trait
distribution in thornpalms,
go to page 2 and try these
missions out if you can.
We're gonna test these
ideas out in the Sim,
but before we start, I just wanna look at
the thornpalm population to
see the variation of traits.
I can see a lot of thornpalms
that seem to have a very
low amount of water storage.
I'm seeing some that seem like they have
a medium amount of water storage.
And I'm actually not finding too many
that have a thick trunk like this one,
with a high amount of water storage.
I'm gonna make a prediction
that maybe a medium amount of rainfall
will result in a high amount
of water storage 50 generations later.
So, let's try that out.
Hmm, It's only been a
couple of generations
but things I'm already noticing
is there's still quite
a bit of the thornpalms
that have a lower water storage
but it now looks like
there's more with a medium water storage.
I'm having trouble finding any
that have a high water storage.
Oh, there's one.
Okay, well here.
Let's fast forward to 50 generations.
So, what I'm noticing after 50 generations
in the thornpalm population,
I'm not seeing any more of the
low, low water storage traits
when we used medium rainfall,
but for medium rainfall environment,
I see a lot of medium
water storage traits.
And I don't see any
thornpalms with the traits
for high water storage.
So, what does that all mean?
Did medium rainfall result in an increase
of high water storage traits?
Why or why not?
Go ahead and press pause now.
Going back into the sim,
it seemed like a medium amount of rainfall
didn't result into a lot of
high water storage traits,
so let's try a different situation.
I have the same starting
population of thornpalms,
but now, I'm going to set it to
where they'll have a
low amount of rainfall,
just like a cactus would.
So, let's see what happens now.
What I'm seeing already happening
is quite a few of the medium water storage
thornpalms are present.
I'm not really seeing that
many, or actually any at all,
with a low amount of water storage,
but I'm noticing a lot of these ones
with thick bases, of a high water storage.
Actually, unlike before that seems
to be all I'm finding now.
So again, let's just pause a moment
and fast forward in time.
This is what I got
when I did this for 50 generations
with a low amount of
rainfall in the environment.
With a low amount of rainfall,
almost every single tree is gone.
There's no more 1, 2, 3,
4, all the way up to 8.
All of the low
and the medium water storage
thornpalms just disappeared.
But, what I am noticing
is the thornpalms with the
high water storage trait,
they did actually survive
and that became the only
trait we saw over time.
So, let's consider.
Did low rainfall in the environment
result in an increase of the
high water storage traits?
Why or why not?
Pause.
Okay, so we're almost
at the end of chapter 1,
with lesson 1.6: Explaining
Changes in Trait Distribution.
So, a useful key concept
here about cause and effect.
Biologists analyzed data about
population and environment,
the causes, to explain
changes in the distribution
of traits in populations, the effects.
And that's actually what we've
been doing this whole time.
We've been thinking about
why would a trait be adaptive
or non-adaptive depending
on the environment
the organism's living in.
So, let's get a little practice in
on describing changes to a population.
What we're gonna be considering is
the thornpalm water storage traits,
and we're going to try to describe
why the distribution of traits
changed in its population.
So, spend a moment
looking at the histogram.
Okay, let's analyze this
together to explain.
Originally, these thornpalms lived
in a relatively high rainfall environment
and at that time there
was mostly thornpalms
that had a low amount of water storage
or a medium amount.
There was only a few
that had a high amount of water storage.
But, 50 generations later,
when the environment
changed to low rainfall,
all we see is just a trait
for level 9 water storage
and there's no variation
in the population.
Well, why did this happen?
If we're thinking about a plant's ability
to survive without water
or without rainfall,
they need an ability
to store water somehow.
What happened is, when
the environment changed
to low rainfall, all of the thornpalms
that did not have the
ability to store water,
eventually died because they weren't able
to complete life functions.
But for those with a level
9 water storage trait,
this was adaptive to low rainfall.
All those with a 9 level
water storage trait
were able to survive, store
water, and reproduce offspring.
Over time, the level 9 water storage trait
became the only one in the population
because it was most adaptive
to its new environment.
Okay, now it's your turn.
Thinking about the ostrilope
fur distribution traits,
based on the information given,
how can you explain why the distribution
of traits changed in this population?
Go ahead and press pause now.
Okay, so wrapping up chapter 1,
we're gonna explain the changes
in the newt population,
and we're gonna look at
the chapter 1 question about
what causes newt population
to become more poisonous.
And just as a reminder of the claims.
Claim 1 said, "Individuals newts became
"more poisonous because they wanted to".
and claim 2 said, "The newt
population became more poisonous
"because of something in the environment".
Now, let's use what we
learned over this chapter
to see if we can either eliminate
or revise some of the claims that we have.
So, let's start by considering claim 1.
Claim 1 said, "Individual
newts became more poisonous
"because they wanted to".
Well, let's think this one through.
I think being poisonous is pretty cool
and I've been wanting, for
the last couple of weeks,
to turn myself into a newt,
so I can have high poison traits.
But, no matter how much I seem to want to,
I'm not becoming a newt.
So, this claim doesn't
seem to make any sense.
The newts couldn't have just wanted
to become more poisonous,
it had to have been something else.
So, let's think some more on claim 2.
Claim 2 said,"The Newt
population became more poisonous
"because of something in the environment".
So, let's think back about
a few key facts we saw.
We saw for certain that, yeah,
the newts definitely became
more poisonous over time
and there's more high poison Newts today
than 50 generation ago.
And what we also know is
our environment changed.
There were no snakes in the
environment 50 generations ago
but there are snakes in the
population's environment today.
Let's use what we know
to revise our claims.
So, we can take this information
and revise our claim to say,
"The newt population became more poisonous
"because the snakes in the
environment caused poison
"to become an adaptive trait".
So, what you need to do,
use the histogram right over there
to explain why the newt
population became more poisonous
because snakes in the
environment caused poison
to be an adaptive trait.
And big hint, your histogram
has a bunch of great evidence,
so go ahead, write, discuss and pause.
Okay, so that's a wrap for chapter 1.
Next time in natural
selection we're gonna answer
how do individuals in a
population get their traits?
So, from me and the Kitty,
we're gonna sign out now
from the fortress of science.
Take it easy and see ya soon!
(calming music)
(electronic music)
