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How Evolution in Isolation Works · Stuff You Should Know

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  Speaker 1: Brought to you by the reinvented two thousand twelve camera.
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  Speaker 1: It's ready. Are you welcome to Stuff you should know?
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  Speaker 1: From how Stuff Works dot Com? Hey there, welcome to
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  Speaker 1: the podcast. I'm Chris Polette. I'm one of the editors
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  Speaker 1: here and with me, as always, is staff writer Josh Fark.
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  Speaker 1: You don't know, okay. I thought we would talk about
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  Speaker 1: what happens when animals evolve in isolation, and basically it
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  Speaker 1: starts with the theory of evolution and how we're all
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  Speaker 1: related exactly. Yeah, and like you said, you hit upon
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  Speaker 1: this theory. I think we should say that not everyone
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  Speaker 1: subscribes to evolution, but if you're a scientist, you most
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  Speaker 1: likely do. Um. There are a few ways to to
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  Speaker 1: go about uh evolving, and one of them is through
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  Speaker 1: evolution and isolation. Um. For that to happen, you have
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  Speaker 1: to go through a speci event. And what that is
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  Speaker 1: is just when one species becomes two or more species,
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  Speaker 1: for example, bears. You want to talk about bears, Sure
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  Speaker 1: we can talk about bears. Okay, Well, the black bear
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  Speaker 1: is the parent species of the polar bear, and it
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  Speaker 1: makes sense if you think about it. There bears, right,
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  Speaker 1: So surely all bears are related, But how did polar
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  Speaker 1: bears become white? Wire black bears still black? I think
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  Speaker 1: evolutionary biologists tend to believe that it was because of
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  Speaker 1: a parapatric speciation event. And parapatrick speciation occurs when UM,
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  Speaker 1: a species becomes so spread out geographically that members in
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  Speaker 1: different areas are are living in different environments undergoing different experiences.
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  Speaker 1: So the black bear up north had a fur coat
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  Speaker 1: that stood out like a sore thumb against the the
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  Speaker 1: white landscape, the snow covered landscape, so they evolved to
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  Speaker 1: be white. Uh, that's not enough. That doesn't cover speciation entirely.
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  Speaker 1: For speciation to be complete, you have to go through
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  Speaker 1: reproductive isolation. And this just means where the members of
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  Speaker 1: the species no longer can produce offspring. It can be
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  Speaker 1: because they developed different genitalia. It can be because they've
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  Speaker 1: developed different time to the year to make different locations
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  Speaker 1: to made in. Either way, if reproductive isolation occurs, aspeciation
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  Speaker 1: event has taken place, okay, um, So basically they just
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  Speaker 1: have to uh, they just have to be different enough
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  Speaker 1: where they're no longer able to reproduce with one another,
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  Speaker 1: and then gradually, you know, become a different species altogether.
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  Speaker 1: That's exactly right. And there's also some other really interesting
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  Speaker 1: aspects to evolution. One of THEE know you know a
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  Speaker 1: lot about that's the evolutionary bottleneck, right, that's true. This
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  Speaker 1: is when a group gets completely or I guess nearly
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  Speaker 1: completely cut off from the main group, so you know,
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  Speaker 1: they are reproducing only with one another. Um. It's it's
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  Speaker 1: like a bottleneck if you think, like a sodo bottle. UM.
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  Speaker 1: But you know that can cause some problems because if
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  Speaker 1: there's a genetic defect, it can be passed down from
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  Speaker 1: generation through generation. Uh. You mentioned in the article a
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  Speaker 1: group of Amish people in Pennsylvania who uh, who had
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  Speaker 1: smaller than had a trade for smaller than normal brains
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  Speaker 1: micro and cephali um. And uh, you know that can
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  Speaker 1: be fatal. So obviously, uh, you know, in this case,
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  Speaker 1: this very small group of people having that trade be
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  Speaker 1: passed down, it was was fatal to that group. Not
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  Speaker 1: a desired trade either, No, definitely not. But you know, Josh,
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  Speaker 1: one of the other examples that you used in the
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  Speaker 1: article that I thought was really cool was the iguanas
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  Speaker 1: that were displaced by Hurricane Maryland. UM. And that that's
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  Speaker 1: sort of an evolutionary bottleneck. And it's also an example
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  Speaker 1: of a different kind of uh speciation ala Patrick, which is,
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  Speaker 1: you know, they're cut off by a geographical boundary. In
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  Speaker 1: this case, they're on an island, separated by you know,
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  Speaker 1: the main group by water, and these these the small
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  Speaker 1: group of iguanas uh floated from Guadaloupe to Anguilla um.
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  Speaker 1: And I think that's I think that's really cool because
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  Speaker 1: you know, it's a completely scientific study. There are no
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  Speaker 1: or there were no iguanas on Anguilla before this happens.
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  Speaker 1: It's a completely natural experiment, right right. You know, they
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  Speaker 1: it wasn't forced. Um. They just happened to notice that
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  Speaker 1: the these iguanas are going to go there, and so
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  Speaker 1: they found out we're gonna find out if there will
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  Speaker 1: be a bottleneck. And also the island rule um, which
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  Speaker 1: is funny that this is an island, but uh yeah,
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  Speaker 1: the the island rule would give them a chance to
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  Speaker 1: see if these iguanas will grow larger or smaller as
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  Speaker 1: a result of being cut off from the main genetic
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  Speaker 1: body of iguanas UM. So it's gonna give give scientists
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  Speaker 1: a chance to see evolution up close and personal. As
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  Speaker 1: it were. Ironically, it was a gift from God to
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  Speaker 1: conduct a natural experiment on evolution. There you go. Well,
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  Speaker 1: you can read all about this and what happens when
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  Speaker 1: animals evolved in isolation on how stuff works dot com.
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  Speaker 1: For more on this and thousands of other topics, visit
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