Free Classroom Resources from HHMI for Teaching Evolution,

Part 2Megan Stine

stinem@hhmi.orgJune 19, 2014

Evolution: Behind the Scenes

Evolving Switches, Evolving Bodies

• Film guides• Virtual lab• Classroom activities:– Using Genetic Crosses to

Analyze a Stickleback Trait

– Modeling the Regulatory Switches of the Pitx1 Gene in Stickleback Fish

Evolving Switches, Evolving Bodies Film

• http://www.hhmi.org/biointeractive/making-fittest-evolving-switches-evolving-bodies

Which phenotype is dominant?

• Assumption: single-gene trait, 2 alleles, normal dominance

• Cross between a marine stickleback and one from Bear Paw Lake

• Parents are homozygous• F is dominant, f is recessive

Predict the results of the crosses

F F

f

f

Ff

Ff

Ff

Ff

Pelvic spines present:absent =

0:11:0

F f

F

f

FF

Ff

Ff

ff

Pelvic spines present:absent =

3:1 1:3

1st generation 2nd generation

Sorting by Phenotype

With pelvic spines Without pelvic spines

Do the data support your hypothesis?

• Sort the F1 cards:– Fish with pelvic spines– Fish without pelvic

spines

• Sort the F2 cards

• Ratio of fish with:without pelvic spines in F1?

• Ratio of fish with:without pelvic spines in F2?

1:0

3.4:1

Was our initial assumption correct? Is this a single-gene trait?

Was your hypothesis correct? Which phenotype is dominant?

Virtual Lab

Natural Selection in Humans

• Film guides• Classroom resources:– Nature of Science– Mendelian Genetics,

Pedigrees, and Chi-square Analysis

– How Fibers Form– Population Genetics

Natural Selection in Humans Film

• http://www.hhmi.org/biointeractive/making-fittest-natural-selection-humans

Mendelian Genetics Activity

• Punnett squares• Pedigree analysis• Pedigree creation• Chi-square analysis• Data prediction

• Important notes:– A is normal allele– S is sickle cell allele– AA has normal RBC

phenotype– AS has sickle cell trait– SS has sickle cell disease

Question #1: Intro Punnett

A S

A

S

• Chance of normal RBC in high and low oxygen?

• Chance of SCD?• Chance of 3 children

with SCD?• Chance of 2 children

with sickle cell trait and 1 with SCD?

• Child without SCD, what chance he/she has trait?

AA

AS

AS

SS

1/4

1/4

1/64

1/16

2/3

Question #6: Intro Pedigree

• Genotype of: – 1st gen male?– 2nd gen daughter?– Individual #3?

• If family moves to lowlands of E. Africa, 4/5 males will have two genetic advantages. What are they?

AS

SS

AS

Human Evolution Click & Learn

Teacher Guides

Holiday Lecture Series

BioInteractive.org

Coming in Fall 2014…

Thank you for your time and attention!

stinem@hhmi.org

Sign up for our newsletter at biointeractive.orgLike us on Facebook!