ShmoopTube

00:04

Here’s your shmoop du jour, brought to you by Charles Darwin.

00:07

Besides coming up with the Theory of Evolution, he uh… had a really awesome beard. [Charles Darwin in a forest]

00:13

So he also had that going for him.

00:16

Allopatric speciation is likely seen... when or where?

00:20

And here are the potential answers...[Mumbling]

00:26

Okay…first off, keep in mind that allopatric speciation is basically the same thing as [lots of islands spread out]

00:32

geographic speciation.

00:34

In other words, we’re talking about different species arising because of factors associated [species of monkey appear on separate islands]

00:38

with their locations.

00:39

Like…maybe a new species of squirrel pops up right outside a mixed nut factory. [Squirrels appear outside a nut factory]

00:45

Got it?

00:46

Good.

00:47

Now let’s go through the potential answers…

00:48

Let’s check out B...”if behavioral mating differences separate neighboring species.”

00:53

This could lead to species diverging, but…it’s not the right answer. [Two monkeys talking on grass]

00:58

Why not?

00:59

Because allopatric speciation is associated with geography, not behavior. [A gorilla scratching it's head]

01:01

B is out.

01:04

C… “…if genetic barriers arise within one population.”

01:08

Genetic barriers arise BECAUSE OF allopatric speciation, not the other way around. [Two tortoises between a DNA helix]

01:12

They could also arise due to mutation.

01:15

Like…with all those X-men folk. [People dressed in X-men costumes]

01:17

Remember, we’re looking for something that is dependent upon geography, so let’s keep

01:21

looking…

01:22

How about D... “…only if natural selection is not occurring”?

01:25

Nope, can’t be this one because natural selection is almost ALWAYS occurring. [Man in a lab stood next to a giant tomato and a average tomato]

01:29

About the only time it doesn’t occur is during the controlled, selective breeding

01:33

of species by humans.

01:36

Go us.

01:37

That leaves us with...A.

01:38

Allopatric speciation is likely seen... on island chains where founder populations [A chain of islands]

01:43

are established on each island.

01:45

Bingo.

01:46

Why?

01:47

Because allopatric speciation occurs if geographical isolation is created… [Birds appear on different plots of island]

01:50

.,..and island chains, like the Galapagos, are perfect places for that to happen.

01:55

Think of Darwin's example of the Galapagos finches. [Pencil drawings of the galapgos finches]

01:57

Various species arose on different islands from a common ancestor after they became isolated

02:02

from one another.

02:04

Sounds like that answers our question, so…

02:05

A it is.

02:07

Will allopatric speciation occur when humans colonize other solar systems? [Man and boy pointing to Charles Darwin on a beach]

02:12

Given enough time, you can probably count on it…

Full Transcript