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Description:

AP Biology 3.3 Evolution. What is a small population of organisms prone to?

Language:
English Language

Transcript

00:04

Here’s your Shmoop du jour, brought to you by small populations.

00:07

If that describes your Twitter following, you may want to consider tweeting about more [James Smith's twitter following page]

00:12

exciting topics.

00:13

And no, corn is not exciting.

00:15

All right, let's take a look at the question…

00:17

A small population of organisms is prone to...what?

00:21

And here are the potential answers

00:28

Let's start at the very beginning. [Caveman starting a fire]

00:30

We hear it's a very good place to start.

00:32

Mutation is a natural process that changes a DNA sequence and the precise order of nucleotides

00:38

within a DNA molecule.

00:40

It's also the reason why it's safe to say that no two people are alike. [Two guys take off their hats]

00:43

So all this time you've called your little brother a mutant?

00:46

You're not too far off base. [Family sitting down for dinner]

00:48

Random genetic changes have little or no effect on a small population of organisms making

00:53

“A” incorrect.

00:55

Moving on to “B,” nonrandom mating. [A couple kissing]

00:58

Nonrandom mating occurs within organisms when there are plenty of potential mates to choose

01:02

from.

01:03

It's provides the opportunity within a large gene pool to pick out a mate based on compatibility, [A large swimming pool]

01:09

or desirable traits.

01:10

In a small population, there’s no chance to pick and choose.

01:14

All you can do is hope your mate likes death metal, because it’s all random selection. [Man picking a mate]

01:19

All of this means that “B” is the wrong answer.

01:21

How about D, high migration rates?

01:23

Well, there's nothing that indicates that a small population has any more desire to

01:27

pick up and move than a larger population would. [Baby deer prancing in a field]

01:30

That's not to say it wouldn't happen given the right circumstance.

01:33

Sometimes you end up with high rent, or irritating neighbors.

01:37

So while a small population may be prone to migration, it is not prone to high migration

01:43

rates, which means answer “D” is incorrect.

01:46

Which leaves us with “C”.

01:48

Genetic drift is the change in the frequency of a gene variant. [Graph depicting change in frequency of a gene variant]

01:52

The smaller the population, the more susceptible it is to dramatic changes in gene frequencies.

01:58

In other words, genetic drift can determine whether an individual within a small population

02:03

reproduces or even survives.

02:06

Genetic drift can have a large impact on a very small population, meaning that C is the

02:09

correct answer.

02:11

And seriously.

02:12

Stop tweeting about corn. [Man tweeting about corn on his mobile]

02:14

No one should care this much about corn. Seriously, come on people.

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