Stuff You Should Know - How Evolution in Isolation Works | Текст песни

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Welcome to Stuff You Should Know from howstuffworks.com.

Chris Pollete

Hey there, welcome to the Podcast. I'm Chris Pollete; I'm one of the editors here and with me, as always, is staff writer, Josh Clark. Hey, Josh.

Josh Clark

How's it going, Chris?

Chris Pollete

Doing okay. I thought we would talk about what happens when animals evolve in isolation and basically it starts with the theory of evolution and how we're all related.

Josh Clark

Exactly. Yeah, and like you said, you hit upon this in theory, I think we should say that not everyone subscribes to evolution but if you're a scientist, you most likely do. There are a few ways to go about evolving and one of them is through evolution and isolation. For that to happen, you have to go through a speciation event, and what that is, just when one species becomes two or more species. For example, bears. You want to talk about bears?

Chris Pollete

Sure. We can talk about bears.

Josh Clark

Okay. Well, the black bear is the parent species of the polar bear. It makes sense if you think about it. They're bears, right, so surely all bears are related but how do polar bears become white; why are black bears still black?

I think evolutionary biologists tend to believe that it was because of a parapatric a speciation event and parapatric speciation occurs when a species becomes so spread out geographically that members in different areas or living in different environments, undergoing different experiences, so the black bear up north had a fur coat that stood out like a sore thumb against the white landscape, the snow-covered landscape so they evolved to be white.

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 the species no longer can produce offspring. It can be because they develop different genitailia, it can be because they've developed different times of the year to mate, different locations to mate in, either way, if reproductive isolation occurs, a speciation even has taken place.

Chris Pollete

Okay. So, basically they just have to be different enough where they're no longer able to reproduce with one another and then they gradually become a different species all together.

Josh Clark

That's exactly right. And there's also some other really interesting aspects to evolution. One of them I know you know a lot about and that's the evolutionary bottleneck, right?