Hi. It's Paul Andersen. And this is disciplinary core idea LS2C. It's
on ecosystem dynamics, functioning and resilience. And so if we look at something like a coral
reef it's an ecosystem. It's made up of a lot of different organisms. But it's also
made up of nonliving materials. So it's like the water, the temperature, the chemistry.
And so if you take an ecosystem like a coral reef and we disrupt it, so we add a disruption,
so that could be a change in the temperature or the chemistry or introducing a new organism.
What you're going to do is you're going to change that ecosystem. And as a result you
might see a change in the organism type. You could see different organism numbers. You
could have a reduction or maybe an increase. You could see extinction of species. You could
see migration. You could see new organisms coming into the area or organisms leaving.
And you could also even see speciation. So the formation of new species. And so disruptions
are going to stress an ecosystem. And depending on the health of the ecosystem it's going
to respond. And so here's some examples. It could be a fire. A fire is going to go through,
sweeps through a forest and then life is going to come back after that. But it might not
be exactly the same as the life that was there before. Or we could have new rock being formed.
So like a lava flow. And then life has to reestablish itself. So these would be more
natural disruptions. Lots of times humans are causing the disruptions. And so pollution
is going to force some organisms to die and some organisms to survive. You might have
new organisms come into an area as a result just of something that we're doing. Or maybe
an invasive species. So we brought a plant here, a Japanese plant called Kudzu. It didn't
have a natural predator. And it just spread across the south. And as a result it's changing
ecosystems wherever it goes. And so organisms are relatively adapted to their environment.
But everything is constantly changing. So let me give you an example of that. This is
a lynx. A lynx is going to be in the northern forests. And it's evolved to live in a cold
kind of a climate. It has these really big feet. It's got quite a bit of fur. In other
words it has all of these adaptions so it can do well. The reason it has such big feet
is so it can run on top of the snow. And so what's going to happen to that environment
over the next few decades? Well it's going to change. As we see increases in the temperature.
As we see global increases in the temperature, that environment is going to change. What's
going to happen to lynx with big feet? Well it might not be as much of an advantage. And
so some of them may die. And maybe some of the ones who have smaller feet might do a
little bit better. And so that's really what's going on. But the health of an environment
is determined based on the number of organisms and the diversity of organisms that you have
there. And so this is a human example, a historical example. So in Ireland, about 30% of the people
who are living in Ireland in the 1800s were feeding almost entirely on potatoes. Their
whole diet was based on potatoes. And what happened was the potato famine. So we had
a potato blight. And this happened all across Europe. But it especially targeted people
in Ireland who were just feeding only on potatoes. So we had this blight. And so what happened
is so many people died. A million people died of starvation and disease in Ireland. A million
of them left. And so if you look at this map over here on the side, each of these dark
regions in Ireland shows a decrease in over 30% of the population. And so what was the
problem? The major problem is that they had put all of their eggs in one basket. They
were just feeding on potatoes. And so when the environment changed they weren't able
to respond. And so in science we tend to call that biodiversity. Biodiversity is going to
be the sum total of different individuals you have in an area. And so if we're looking
at a rain forest like this, I can see so many species already. And if we compare that to
a plantation here, we really only see one species out here. And so which is healthier?
Well the one that's more biodiverse is going to be more healthier. And what we mean by
healthy is that it's able to respond to disruptions or changes in its environment. And so what's
the teaching progression for this? Well in the lower elementary grades you need to tell
your students that plants and animals require things from their environment. If their environment
changes, let's say it gets too hot or too cold, that can damage or even kill plants
and animals in an area. If there's no water. It there's not enough nutrients that they
might get from the air. If there's no food in that area they're going to be damaged and
they might even die as a result of changes in their environment. To get more specific
in the upper elementary grades, you want to talk about what happens when the environment
changes. And so as we change the environment, no food, too cold, too warm, one thing that
could happen is certain species could do well. They could survive and they could pass their
genes on to the next generation. But they also might migrate. In other words some species
might leave that area. And then new species might come in. So we could have migration.
Then finally we could have death. And so there could be a selective pressure where maybe
they don't do well as a result of environmental changes. As we move into the middle school
we want to talk about ecosystems. What are all the parts of an ecosystem. And then remind
our students that they're incredibly dynamic. They constantly are changing. When you look
at it your just looking at it at one point in time. But they change over time. And then
remind them that the biodiversity is a good signal of how healthy that environment is.
And the reason why is that you have more species. And so as the environment changes you're more
likely to be able to respond to that. And then finally as you move on to high school
you want to talk about the stability of an environment. The stability of an ecosystem.
And so there are always going to be changes. So if we're looking at a coral reef like this,
there have always been fluctuations in temperature. Fluctuations in chemistry. Small fluctuations
of organisms coming in and out. And they remain stable over time. But sometimes it changes
too quickly and they can't do well. So right now we're seeing huge changes in the temperature
of our planet. And as a result the water is warming. The corals are starting to bleach.
And really that environment can't respond to that. In other words that's too big a disruption.
And so that's what ecosystems are. Sometimes they're resilient. Not so much sometimes.
A lot of that is based on biodiversity. And I hope that was helpful.