WEBVTT - How Evolution in Isolation Works

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<v Speaker 1>Brought to you by the reinvented two thousand twelve camera.

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<v Speaker 1>It's ready. Are you welcome to Stuff you should know?

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<v Speaker 1>From how Stuff Works dot Com? Hey there, welcome to

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<v Speaker 1>the podcast. I'm Chris Polette. I'm one of the editors

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<v Speaker 1>here and with me, as always, is staff writer Josh Fark.

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<v Speaker 1>You don't know, okay. I thought we would talk about

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<v Speaker 1>what happens when animals evolve in isolation, and basically it

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<v Speaker 1>starts with the theory of evolution and how we're all

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<v Speaker 1>related exactly. Yeah, and like you said, you hit upon

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<v Speaker 1>this theory. I think we should say that not everyone

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<v Speaker 1>subscribes to evolution, but if you're a scientist, you most

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<v Speaker 1>likely do. Um. There are a few ways to to

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<v Speaker 1>go about uh evolving, and one of them is through

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<v Speaker 1>evolution and isolation. Um. For that to happen, you have

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<v Speaker 1>to go through a speci event. And what that is

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<v Speaker 1>is just when one species becomes two or more species,

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<v Speaker 1>for example, bears. You want to talk about bears, Sure

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<v Speaker 1>we can talk about bears. Okay, Well, the black bear

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<v Speaker 1>is the parent species of the polar bear, and it

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<v Speaker 1>makes sense if you think about it. There bears, right,

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<v Speaker 1>So surely all bears are related, But how did polar

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<v Speaker 1>bears become white? Wire black bears still black? I think

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<v Speaker 1>evolutionary biologists tend to believe that it was because of

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<v Speaker 1>a parapatric speciation event. And parapatrick speciation occurs when UM,

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<v Speaker 1>a species becomes so spread out geographically that members in

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<v Speaker 1>different areas are are living in different environments undergoing different experiences.

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<v Speaker 1>So the black bear up north had a fur coat

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<v Speaker 1>that stood out like a sore thumb against the the

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<v Speaker 1>white landscape, the snow covered landscape, so they evolved to

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<v Speaker 1>be white. Uh, that's not enough. That doesn't cover speciation entirely.

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<v Speaker 1>For speciation to be complete, you have to go through

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<v Speaker 1>reproductive isolation. And this just means where the members of

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<v Speaker 1>the species no longer can produce offspring. It can be

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<v Speaker 1>because they developed different genitalia. It can be because they've

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<v Speaker 1>developed different time to the year to make different locations

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<v Speaker 1>to made in. Either way, if reproductive isolation occurs, aspeciation

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<v Speaker 1>event has taken place, okay, um, So basically they just

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<v Speaker 1>have to uh, they just have to be different enough

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<v Speaker 1>where they're no longer able to reproduce with one another,

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<v Speaker 1>and then gradually, you know, become a different species altogether.

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<v Speaker 1>That's exactly right. And there's also some other really interesting

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<v Speaker 1>aspects to evolution. One of THEE know you know a

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<v Speaker 1>lot about that's the evolutionary bottleneck, right, that's true. This

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<v Speaker 1>is when a group gets completely or I guess nearly

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<v Speaker 1>completely cut off from the main group, so you know,

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<v Speaker 1>they are reproducing only with one another. Um. It's it's

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<v Speaker 1>like a bottleneck if you think, like a sodo bottle. UM.

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<v Speaker 1>But you know that can cause some problems because if

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<v Speaker 1>there's a genetic defect, it can be passed down from

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<v Speaker 1>generation through generation. Uh. You mentioned in the article a

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<v Speaker 1>group of Amish people in Pennsylvania who uh, who had

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<v Speaker 1>smaller than had a trade for smaller than normal brains

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<v Speaker 1>micro and cephali um. And uh, you know that can

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<v Speaker 1>be fatal. So obviously, uh, you know, in this case,

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<v Speaker 1>this very small group of people having that trade be

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<v Speaker 1>passed down, it was was fatal to that group. Not

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<v Speaker 1>a desired trade either, No, definitely not. But you know, Josh,

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<v Speaker 1>one of the other examples that you used in the

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<v Speaker 1>article that I thought was really cool was the iguanas

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<v Speaker 1>that were displaced by Hurricane Maryland. UM. And that that's

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<v Speaker 1>sort of an evolutionary bottleneck. And it's also an example

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<v Speaker 1>of a different kind of uh speciation ala Patrick, which is,

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<v Speaker 1>you know, they're cut off by a geographical boundary. In

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<v Speaker 1>this case, they're on an island, separated by you know,

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<v Speaker 1>the main group by water, and these these the small

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<v Speaker 1>group of iguanas uh floated from Guadaloupe to Anguilla um.

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<v Speaker 1>And I think that's I think that's really cool because

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<v Speaker 1>you know, it's a completely scientific study. There are no

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<v Speaker 1>or there were no iguanas on Anguilla before this happens.

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<v Speaker 1>It's a completely natural experiment, right right. You know, they

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<v Speaker 1>it wasn't forced. Um. They just happened to notice that

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<v Speaker 1>the these iguanas are going to go there, and so

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<v Speaker 1>they found out we're gonna find out if there will

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<v Speaker 1>be a bottleneck. And also the island rule um, which

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<v Speaker 1>is funny that this is an island, but uh yeah,

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<v Speaker 1>the the island rule would give them a chance to

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<v Speaker 1>see if these iguanas will grow larger or smaller as

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<v Speaker 1>a result of being cut off from the main genetic

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<v Speaker 1>body of iguanas UM. So it's gonna give give scientists

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<v Speaker 1>a chance to see evolution up close and personal. As

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<v Speaker 1>it were. Ironically, it was a gift from God to

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<v Speaker 1>conduct a natural experiment on evolution. There you go. Well,

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<v Speaker 1>you can read all about this and what happens when

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<v Speaker 1>animals evolved in isolation on how stuff works dot com.

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<v Speaker 1>For more on this and thousands of other topics, visit

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<v Speaker 1>how stuff works dot com. Let us know what you think.

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