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- [Voiceover] DNA is special in that
it can really start to tell us about
the evolutionary dynamics of organisms.
This is absolutely critical in trying to figure out
what we can do today to protect species
and ecosystems from the potentially devastating consequences
of projected climate change.
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Well here we are at UC Santa Cruz
set in a beautiful coastal redwood forest.
- You know these sequoias are an ancient family of trees.
They saw dinosaurs come and go.
They even pre-date flowers and even grasses.
- And they survived the ice ages!
- That's right and that's why we're here today,
to meet Beth Shapiro.
They're using genomics to see the impacts of climate change.
- On not only plants,
but also animal populations.
- You're right let's go to the lab,
and see what she's up to.
- So how do you collect all these samples?
Do you have a lot of collaborations with other labs?
- We collaborate with other labs,
and with paleontologists who work in the field,
and also with people from
different museums around the world.
- How do you get the DNA from these samples?
- [Beth] So after we've gone up into the Arctic
or into a museum collection,
and we've picked out the bones that we want to process,
we will take a very small fragment of these bones
back into our clean lab
where we would grind it into a fine powder
and extract the DNA,
and then prepare into sequencing library,
then bring it over and stick in on the machine
and hit the button.
- How do you deal with sample contamination?
- There are two types of contamination
that we have to deal with,
so if I were to extract DNA from this horse bone,
I would get a whole bunch of DNA that belongs to this horse,
but also DNA that belonged to any of the environmental
microbes or fungi that colonized this bone
while it was buried in the soil.
The second type of DNA is more insidious
is that is just that DNA is everywhere.
Me by touching this bone,
I'm depositing my own DNA into this bone.
- Do you also work with other fossils?
- We can get DNA from
pretty much any organism that was alive
as long as the DNA is not too decayed.
We can actually understand how
the trees were changing
and how this in turn was shaping the changes
that we're seeing in horses.
What we're really seeing is that
populations become isolated from one another
in these tiny little refugia.
Its this rapid fragmentation
that's caused by these rapid periods of climate change
that seems to be most important in determining
whether a species is likely to go extinct or not.
We were able to recover a bone a few years ago
from the Yukon that we think is around 700,000 years old.
We were able to recover enough information to piece together
the entire horse genome from that 700,000 year old horse.
- What's your favorite extinct animal?
- Some of my favorite are the largest ones.
There was a giant hyper carnivorous bear
called Arctodus or the short-faced bear.
He was pretty scary.
There was also a giant beaver.
So as you can see
this is a very very large example of something
that today is quite a lot smaller.
People have found pieces of wood that have the tooth marks
that have been gnawed by these giant beavers,
which is one of the ways that we know that they
were such incredible ecosystem engineers.
- What inspires you about this work?
- I get to go up into the Artic
and dig up bones like this (laughs).
It's like being a DNA explorer.
It's telling us about us about our history
about the history of animals that we
still live with and work with today.
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- [Voiceover] This is around 35,000 years ago
and this area right here which we call Beringia
was actually a very rich and productive grassland
that was home to lots of different species
and this land bridge was an important conduit
for exchange between Asia and North America,
and then as it started to get colder,
as the ice age, which peaked around 20,000 years ago,
progressed we saw the expansion of glaciers,
and what this did, really importantly,
is cut-off gene flow between populations
up here in Beringia
and down here in the central
and southern part of North America
for 10 maybe even 15,000 years.
These populations were seperated
and genetically they began to diverge from each other,
and then as the ice age ended
we saw these glaciers start to separate from each other
and form what's commonly known as the ice-free corridor
and its thought that a lot of species, including humans,
used this ice-free corridor as a means
to go from one place to another.
So after thousands of years of isolation fragmentation,
all of the sudden these populations will
once again able to mix.
Many of the species that we studied went extinct in Beringia
bison for example and horses,
much earlier than they did
in the central part of North America,
and we're really just beginning to
understand why that might have been.
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- What can we learn from your work to plan for the future?
- What we're really hoping to be able to learn
by gathering these bones
and other types of environmental data
that go back through time in the permafrost
is how species in the past
responded to past periods of rapid climate change.
For us the focus really is the last ice age
the transition from the coldest part of the last ice age
into warm interglacial period that we're in today.
We want to know using DNA extracted from these remains
how species and populations and communities
grew shrank or moved to different areas
as a response to this period of rapid climate warming,
because we'd really like to be able to make
more informed decisions about how to protect
living species in the face of projected climate change.
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- It's amazing how climate change really can separate
and isolate these populations.
- And that puts them under immense pressure
and sets them on the path to extinction.
- That's true and hopefully genomics
will tell us how climate change
is going to impact our futures.
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