Warm Up 2/27 What is allele frequency? What are the four ways evolution occurs?

Warm Up 2/27

What is allele frequency?

What are the four ways evolution occurs?

Evolution Island

Finish the lab now!!

After the Lab Staple all Teammates’ papers together.

I will grade 1 of them…. You don’t know whose it is.

Quick Review… Change in allele frequency in a population is called

Change in allele frequency due to random/chance is called (remember the coywolves)

A change in the DNA sequence that offers an advantage and results in that change being passed on to other generations is evolution by

Mutation

Change in allele frequency in a population due to MIGRATION is:

Gene Flow

Change in allele frequency due to selection pressures in their environment is called:

Natural Selection

EVOLUTION

Genetic Drift

3 Different Types of Natural Selection

1. Disruptive

2. Directional

3. Stabilizing

Disruptive Selection

Disruptive selection – FAVORS EXTREMES

It is a type of natural selection that selects against the

average individual in a population.

Disruptive selection is the rarest of the three types of

natural selection.

Disruptive Selection

Remember, it favors EXTREMES.

London Peppered Moth Industrial areas – black moths. Rural areas – light colored moths.Very few medium colored moths.

Stabilizing Selection Stabilizing selection – FAVORS AVERAGE

It is a type of natural selection that favors the

average individuals in a population.

This process selects against the extreme

phenotypes

Diversity in a population is decreased due to

stabilizing selection

Stabilizing Selection - Example

Stabilizing selection works mostly on traits that are polygenic.

Since stabilizing selection favors the middle of the road, a blend of the genes is often what is seen.

Many human characteristics are a result of stabilizing selection. Human birth weight is not

only a polygenic trait, but it is also controlled by environmental factors.

Infants with average birth weight are more likely to survive than a baby that is too small or too large.

Directional Selection

Directional Selection – FAVORS *ONE* EXTREME

Think – this drives selection in one DIRECTION over the other

This phenomena is usually seen in environments that have changed over time. Changes in weather, climate, or food availability lead to directional selection.

Directional Selection - Example

The Texas Longhorn is an example of the effects of directional selection.  The long horns were advantageous for defending young calves from predators - so horn length increased in feral herds in the American Southwest between the early 1500s-1860's.  The trend is now maintained through artificial selection by ranchers.  Do you think the horn length would change if the now predator-free cattle were not being selected for artificially?

So when you think of DIRECTIONAL Selection…

Think of…

Moon Bounce

Choose one person to be the astronaut. The other teammates hold each elbow and waist of the astronaut. Count 3-2-1, the astronaut jumps

and the teammates boost the astronaut at the top of their jump.

Types of Natural Selection

http://education-portal.com/academy/lesson/types-of-natural-selection.html

Scenario 1

Tongue length in anteaters in polygenetic and therefore tongues come in a range of lengths. Give (1) example of how directional selection might be acting upon this trait, with a graph and pictorial representation.

If it was particularly hot one summer and ants were making their hills farther below the surface, anteaters with shorter tongues wouldn’t be able to find food.

Practice Scenarios

You will receive a scenario – work it in your spiral.

When everyone at your table is done, rotate the scenarios.

Once you have completed all 4, compare with your team.

Teams for your scenarios….

Team 1 Team 2 Team 3 Team 4 Team 5 Team 6 Team 7

Alexia Addison Lance Alexa Luis Malcolm Benjamin SC

Dirk Ashleigh Lauren Alexis Benjamin S Angela Halea

Justin Anthony G Rebecca Henry Kaila Thomas Anthony R

Susan Matthew Jonathan Christopher Ethan Noe  

Teams for your scenarios

Team 1 Team 2 Team 3 Team 4 Team 5 Team 6 Team 7

Kendall Jonathan Aria Cuauhtli Mattison Wynton Jessica

Gregory Kate Destinylynn Laura-Claire Contessa Grace Sarah

Ashlee Emily Carlos Tanner Dakota Maia Abraham

Carson Abel Cameron Kayla Matthew G Emilio Liam

  Kallysta Briana