CO: I will analyze and evaluate the effects of other evolutionary

mechanisms.

LO: I will write a diagram for my notes. I will talk with my classmates about

other evolutionary mechanisms.

A gene pool is the total number of genes of every individual in an interbreeding

population.

Evolution can be defined as a change in the gene pool over time.

There are 5 factors that can affect the frequency of a gene in the gene pool.

1. Genetic Mutation2. Natural Selection3. Small Population4. Non-random mating5. Gene Flow

1. Genetic Mutation:• Changes in DNA that happen due to errors in

replication, transcription, translation, or because of environmental factors.– The source of all new genes/traits in a population

2. Natural Selection• survival of the fittest• advantageous genes are

passed on to the next generation while harmful genes are eliminated

• the driving force of evolution

3. Small Population• Genetic Drift is a

random change in the frequency of alleles in a population. This has an especially big effect in small populations.

• A) Bottleneck effect- when a large portion of a population dies causing a significant decrease in the size of the gene pool.

3. Small Population• B) Founder effect- when a few individuals from

a population leave and start another population in a different location. This also decreases the size of the gene pool in the new population.

Happy Thursday!Please get out your notes from

yesterday (with the hand on it) so we can begin right when the bell rings!

Did you know?Your stomach needs to produce a new layer of

mucus every two weeks or it would digest itself.

Which mechanism is this?Amish people are required by their religion to

only marry and have children with other Amish people.

Which mechanism is this?A small group of birds flies from the mainland to an

island and starts a new colony. (The birds never return to the mainland.)

4. Non-Random Mating• Not all mates are created equal.• In many species, mates are not

selected at random. Instead they are chosen for specific characteristics. Many organisms compete for mating rites. Strong and good-looking organisms are typically favored.

• This limits the size of the gene pool because only the genes of the mating individuals are passed to the next generation.

5. Gene Flow

Gene flow is the movement of genes into or out of a population.

A) Emigration- when individuals leave a population decreasing the size of the gene pool.

B) Immigration- when individuals from a different population enter a new population and begin breeding. This increases the size of the gene pool.

Does this demonstrate emigration or immigration?

A lioness joins a new pride and has cubs with the male lion.

Which mechanism is this?

The DNA sequence in a bird is changed from ATT CCG TTG to TTA CCG TTG which changes the beak shape from long and thin to short and fat.

Which mechanism is this?

Peppered moths are eaten by birds. The moth color varies from light to dark. Light colored moths can blend in with a nearby species of tree.

In the 1800s factories released large amounts of soot, which changed the tree color, so the birds were able to more easily find the lighter moths instead of the darker moths.

Which mechanism is this?Northern elephant seals were hunted almost to

extinction by people in the 1890s. The remaining population has reduced genetic variation.

Effects of Gene Pool Size

• A decrease in the size of a gene pool increases the speed of evolution and visa versa.

Mix-Freeze-Group

2 43• I am going to survive! Because I have the best genes for my

environment.• I am HUGELY affected by genetic drift.• I am VERY picky. I will only choose you, because your traits are

most attractive to me.• I am a mistake in the DNA sequence

5Natural Selection

SmallPopulation

GeneticMutation

Non-RandomMating

Now…let’s chat about the patterns of evolution!