How Evolution in Isolation Works

How does isolation spur evolution? Check out this HowStuffWorks podcast to learn more about speciation and evolution.

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Episode Transcript

Speaker 1 (00:00):
Brought to you by the reinvented two thousand twelve camera.
It's ready. Are you welcome to Stuff you should know?
From how Stuff Works dot Com? Hey there, welcome to
the podcast. I'm Chris Polette. I'm one of the editors
here and with me, as always, is staff writer Josh Fark.
You don't know, okay. I thought we would talk about

(00:21):
what happens when animals evolve in isolation, and basically it
starts with the theory of evolution and how we're all
related exactly. Yeah, and like you said, you hit upon
this theory. I think we should say that not everyone
subscribes to evolution, but if you're a scientist, you most
likely do. Um. There are a few ways to to
go about uh evolving, and one of them is through

(00:44):
evolution and isolation. Um. For that to happen, you have
to go through a speci event. And what that is
is just when one species becomes two or more species,
for example, bears. You want to talk about bears, Sure
we can talk about bears. Okay, Well, the black bear
is the parent species of the polar bear, and it
makes sense if you think about it. There bears, right,

(01:05):
So surely all bears are related, But how did polar
bears become white? Wire black bears still black? I think
evolutionary biologists tend to believe that it was because of
a parapatric speciation event. And parapatrick speciation occurs when UM,
a species becomes so spread out geographically that members in
different areas are are living in different environments undergoing different experiences.

(01:29):
So the black bear up north had a fur coat
that stood out like a sore thumb against the the
white landscape, the snow covered landscape, so they evolved to
be white. Uh, that's not enough. That doesn't cover speciation entirely.
For speciation to be complete, you have to go through
reproductive isolation. And this just means where the members of

(01:52):
the species no longer can produce offspring. It can be
because they developed different genitalia. It can be because they've
developed different time to the year to make different locations
to made in. Either way, if reproductive isolation occurs, aspeciation
event has taken place, okay, um, So basically they just
have to uh, they just have to be different enough

(02:14):
where they're no longer able to reproduce with one another,
and then gradually, you know, become a different species altogether.
That's exactly right. And there's also some other really interesting
aspects to evolution. One of THEE know you know a
lot about that's the evolutionary bottleneck, right, that's true. This
is when a group gets completely or I guess nearly

(02:35):
completely cut off from the main group, so you know,
they are reproducing only with one another. Um. It's it's
like a bottleneck if you think, like a sodo bottle. UM.
But you know that can cause some problems because if
there's a genetic defect, it can be passed down from
generation through generation. Uh. You mentioned in the article a

(02:57):
group of Amish people in Pennsylvania who uh, who had
smaller than had a trade for smaller than normal brains
micro and cephali um. And uh, you know that can
be fatal. So obviously, uh, you know, in this case,
this very small group of people having that trade be
passed down, it was was fatal to that group. Not

(03:17):
a desired trade either, No, definitely not. But you know, Josh,
one of the other examples that you used in the
article that I thought was really cool was the iguanas
that were displaced by Hurricane Maryland. UM. And that that's
sort of an evolutionary bottleneck. And it's also an example
of a different kind of uh speciation ala Patrick, which is,

(03:37):
you know, they're cut off by a geographical boundary. In
this case, they're on an island, separated by you know,
the main group by water, and these these the small
group of iguanas uh floated from Guadaloupe to Anguilla um.
And I think that's I think that's really cool because
you know, it's a completely scientific study. There are no
or there were no iguanas on Anguilla before this happens.

(04:00):
It's a completely natural experiment, right right. You know, they
it wasn't forced. Um. They just happened to notice that
the these iguanas are going to go there, and so
they found out we're gonna find out if there will
be a bottleneck. And also the island rule um, which
is funny that this is an island, but uh yeah,
the the island rule would give them a chance to
see if these iguanas will grow larger or smaller as

(04:23):
a result of being cut off from the main genetic
body of iguanas UM. So it's gonna give give scientists
a chance to see evolution up close and personal. As
it were. Ironically, it was a gift from God to
conduct a natural experiment on evolution. There you go. Well,
you can read all about this and what happens when
animals evolved in isolation on how stuff works dot com.

(04:47):
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