BELLRINGER – On Pg. 17 in your BIN… Define the following terms in your own words as a review from last semester (I shouldn’t see anyone looking up definitions): Allele Genotype Phenotype Explain in your own words how proteins are made from DNA

Alternate Patterns of Evolution How else do populations evolve?

Evolution Population change over time… So what exactly is changing? GENE POOL: The combined genetic information of all members of a population A population’s gene pool can change through: Natural Selection Sexual Selection Genetic Drift Gene Flow Mutations

How does natural selection affect gene pool of a population? At this point, you all should be able to tell me….

Remember! Natural Selection acts on the individual BUT A population is the unit of evolution

Sexual Selection Selection in which certain traits enhance mating success… and those traits are then passed along to offspring

How does Genetic Drift affect gene pool of a population? Refers to changes in a population’s gene pool due to chance

What is an example of Genetic Drift? The Bottleneck Effect: Occurs when a natural disaster (or some other event) causes a drastic reduction in size of a population Bottlenecking usually reduces the variation in a population

Bottleneck Effect Example (Don’t need to write) Northern elephant seals Humans had at one point hunted their numbers down to 20 individuals Numbers have rebounded, but still show very little genetic variation

What is another example of Genetic Drift? Founder’s Effect: Occurs when a few members of a population colonize an isolated location The smaller the number of founders, the less diversity in the gene pool

Founder’s Effect Example (Don’t Need to write) Afrikaner population in South Africa A small group of Dutch settlers Today, they have an unusually high number of cases of Huntington’s Disease Those original Dutch colonists just happened to carry that gene with unusually high frequency.

How does Gene Flow affect gene pool of a population? Refers to genetic exchange due to the migration of individual genotypes between populations Ex: Brown beetles enter into a community consisting solely of green beetles, creating offspring with greater color diversity. Ex: Blue-eyed people from Sweden move to a small town in Mexico where people all have brown eyes. When they mate, some of their children now have blue eyes.

Checkpoint: Do you think the Galapagos Islands would have a lot of gene flow or very little? How would this affect the organisms that live there?

Mutations Change in the DNA sequence of a gene Why does this matter? DNA RNA Amino Acid (Protein)

Brown Snakes (AAT-TTA-CCG-TTC)

Snakes on a Plain

Green Snakes (AAT-TTA-CCG-TTG)

Tons of Brown Snakes, One Green Snake

What Will Happen Next? Which snake is more fit for its environment?

Tons of Green Snakes, Only One Brown Snake!

There’s an Extreme Drought! What happens now??

Now Brown is Better!

Think About It! Question In Other Words (Example) Answer What makes a trait better than another? Why was it better to be a green snake on a green field? Why does survivability lead to an increase of a trait in a population? Being green helped the snake blend into the green field. Why did that lead to more and more green snakes? How do new traits arise? How did the green snake come into existence? What happens to good traits? What happens to the green snakes on the green field? What happens to bad traits? What happens to the green snakes after the drought? Think About It!

Genetics  Evolution Evolution is directly related to genetics! Changing genes over time allows for changing species over time!

In which of the following types of societies would genetic drift have the least likelihood of causing rapid evolution? a) A band of 12 isolated humans living 70,000 years ago in Southern Africa b) Japan today c) A community of 40 members of a religious sect who have had nothing to do with their neighbors in Pennsylvania for 8 generations

High frequencies of rare genetically inherited traits in people who share a common ancestor is most likely the result of: a) natural selection b) the founder’s effect c) convergent evolution d) Huntington's disease

The fact that South and Central American Indians are nearly 100% type O blood is best explained as being the result of: a) genetic drift b) natural selection c) the founder’s effect

Which of the following is true of genetic bottlenecks? a) They occur when there are major environmental changes that alter natural selection so that most members of a species die before reproducing. b) The result is usually increased genetic diversity in a population following a genetic bottleneck. c) They reduce the fertility of the survivors.

BELLRINGER - On Pg. 8 of your notebook… Use the textbook under your desk to find the Hardy-Weinberg equation and explain what it is and what it is used for.