AP Biology 4.1 Evolution

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

geographic speciation.

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

with their locations.

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

Got it?

Good.

Now let’s go through the potential answers…

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

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

Why not?

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

B is out.

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

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

They could also arise due to mutation.

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

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

looking…

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

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]

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

of species by humans.

Go us.

That leaves us with...A.

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

are established on each island.

Bingo.

Why?

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

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

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

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

from one another.

Sounds like that answers our question, so…

A it is.

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

Given enough time, you can probably count on it…