Natural Selection Intervention

Unit 1: Natural Selection Test Intervention Assignment

Intervention- action taken to improve a situation

This assignment is to review our most missed concepts to help you better understand them or make your current level of understanding even better.

Data for populations that shows a significant and noticeable downward trend.

Decrease

Populations fluctuate (go up and down) over time. But, if there is no obvious trend of increase or decrease it is overall stable.

Stable

Data for populations that shows a significant and noticeable upward trend.

Increase

Not all tables will show a complete downwards trend like this one. They may have an occasional increase. However, if overall the number goes down then it is decreasing.

Table

A graph can also be used to show this. This graph has a few small uprises, but overall it is showing a downward trend.

Graph

Stable does not mean entirely unchanging. We do not live in a world where a population stays the exact same number. However, if they stay within a small range without great changes, it would be considered stable.

Table

A graph can also be used to show this. This graph has a few areas where it goes slightly up or down, but overall it is pretty much the same. This is considered stable.

Graph

Not all tables will show a complete upwards trend like this one. They may have an occasional decrease. However, if overall the number goes up then it is increasing.

Table

A graph can also be used to show this. This graph has only an eventually rise, but it could also have occasional downward dips. So long as overall it is showing an upward trend.

Graph

Multiple Choice

This table is showing a population that is...

• Increase

• Stable

• Decrease

Multiple Choice

This table is showing a population that is...

• Increase

• Stable

• Decrease

Multiple Choice

Compare these 2 tables. From both before and after the mutation this population is...

• Increase

• Stable

• Decrease

There is no significant change of the population's size at any point.

Stable

This random mutation is bad for the organism itself. It decreases it's chance of survival.

Harmful

Neutral mutations neither help or hurt the organism. They are just something new, rare, or different.

Neutral

This random mutation is goof for the organism itself (NOT for us). It increases it's chance of survival.

Beneficial

​Mutations

​Mutations are random changes to the DNA, the genes. They happen before birth when eggs are first fertilized.

Harmful mutations die out before they enter a population. The organism usually dies before it can pass on its genes.

Harmful

​Mutations

Beneficial mutations almost always become more common over time because they are helpful to an organism's survival. Organisms with that mutation will breed more often and have more babies that survive. They spread that mutation even further.

Neutral will also get passed down by random chance as they neither help nor hurt the individuals.

Neutral and Beneficial

​Mutations

Multiple Choice

Which type of mutation would this be if this bird was albino in the wild?

• Beneficial

• Neutral

• Harmful

This bird is easily seen by predators and would be killed in the wild.

Harmful

Multiple Choice

You have here a table showing the population before and after a mutation spread throughout it. What type of mutation was it?

• Beneficial

• Neutral

• Harmful

As previously stated, this population remained stable. This mutation did not increase the population (beneficial) or decrease the population (harmful). It had no effect on the population so it is stable.

Neutral

Multiple Choice

At which month do the green beetles first have an advantage (start to increase)?

• May

• July

• August

• September

The month where they first START to increase is July. That is where the line first starts to go up.

July

Natural = naturally occurring

This happens on it its own in the wilderness. The traits that help organisms to survive are the traits that become more common.

Natural Selection

Artificial = Fake

This is human driven selection. We choose which traits we want (desirable traits) and breed to get them.

Artificial Selection

Types of Selection

This can happen usually in 2 ways. We choose what animals to breed or which animals to pollinate. By doing this we get the traits that we want.

Another way is through genetic modification. This means we add or take away some parts of the DNA to get what we want.

Either way the end result is the same. We get the desired traits that we want. However, this limits variation in a species. There is no random chance and some traits are removed entirely.

Artificial Selection

As shown in the image above, a random change happens, a mutation. If it is helpful it spreads throughout the population causing a change over time.

Natural Selection

Multiple Choice

What is one possible downside to artificial selection?

• Undesirable traits become more common. 

• 
  Genetic diversity can be lost in a population.

• All genetic information is inherited from one parent.

• It takes longer to breed desired traits than it would in nature. 

A possible downside of Artificial Selection is less genetic diversity.

We are choosing the traits we WANT (desired traits). Other traits can be completely removed by this. The UNDESIRED traits are being removed by us. We don't breed dogs that we don't want.

This also allows desired traits to become more common much faster than in nature. In nature the traits spread slowly and randomly over time.

A possible downside of Artificial Selection is less genetic diversity.

Plus the "desired" traits we want are always the traits that would be more common in nature. Remember the pug! We made it that way, but it would not survive in the wild.

Multiple Choice

Why do animals in nature change over time?

• Predators caused the change on purpose

• Environmental changes cause populations to adapt through natural selection.

• Natural selection caused the environment to change and the population to adapt.

• The species wanted to change so it did.

Why do animals in nature change over time?

Predators caused the change on purpose

This just doesn't make sense. Predators don't choose how their prey changes over time.

Environmental changes cause populations to adapt through natural selection.

This is how things change over time. They adapt due to natural selection.

Natural selection caused the environment to change and the population to adapt.

Read this carefully. Natural Selection does NOT change the environment.

The species wanted to change so it did.
This also doesn't make sense. Organisms cannot choose to change.