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Reminders
• End of the semester is in a week a half!
• Check your student view• Make an appointment
with Miss Baker for make-up work!
• Re-take for Natural Selection Exam Due Friday
Variation Lab
Purpose
• Why did we do this lab?• What relevance does it have to
your life?
How we look at our data:•Did you all get measurements in cm?• If you didn’t take all your measurements in cm, can you
easily compare heights using different units of measurement? Why or why not?•Did you all measure the apple circumferences the same
way as neighboring groups from which you received data? How can you be sure?•Why were our graphs so problematic?•Do your graphs tell you anything with a degree of certainty
about a population of spinach plants? Why or why not?•Can we learn about selective pressures from our small
amount of data? Why or why not?•Why do we need a larger sample size?
Let’s combine our data to make a class data set
• Report your data on the white boards around the classroom.
• Write down the total variation for spinach leaf width in the population in a data table in your lab and create a new graph.
• Answer the questions in the end of your lab packet with the new data set.
• You will have 15 minutes to do this!• Use this new information to answer your
homework, this power point is on the wiki page.
Types of Selection:
• Stabilizing• Directional• Disruptive
Directional Selection:
Stabilizing Selection:
Disruptive Selection:
Re-evaluating the data:
• What are some possible reasons (selection pressures) for the shape of the class spinach leaf graph?• How could we test these
hypotheses?
Definitions:Adaptation-a trait that provides some
type of advantage to organisms in the struggle for survival
Examples: speed, height, fur/skin color, claw length, flight
Diajayne Nick
Sam S Phillis
3th Hour
Dylan Aiesha
Rania Felix
Theresa Kassi B
Jake M Austin I
Sydnee
Kevin Jessica
Katie W Harrson
Tiana Tangela
Katie T Connor
Reed Jasmine
Ben S Tony
Samantha Tyanna
Joneica Elijah
Aleah Jesse
Front White Boards
Windows in back
Ruska’s Desk
Selection Pressure• Anything that can
prevent an organism from passing on its genetic material
• Some good examples are: predators, and competition for food, shelter, or mates
Variation
• Variety (or differences) of traits WITHIN A SPECIES.
How do we get variation?1. Genetic Shuffling in Anaphase I of
meiosis2. Mutation to DNA passed down to
offspring (very rare!)
Evolution is:
• Genetic change in population over time.• These changes are seen in
populations not in individuals
Compare and Contrast Artificial Selection and Natural Selection
• Variation in traits exists
• Breeder selects favorable traits in organism
• Breeder mates animals with the favorable traits more than other organisms
• Desired traits become more common in population
• Variation in traits exists• Nature “selects” favorable
traits in organism because some of these trait give a reproductive advantage
• Organisms with favorable traits survive better and have more offspring
• Traits that give a reproductive/survival advantage become more common in population
Make some predictions:• If we saw the
population of an apple-eating-insect grow in size, and we saw an apple fruit circumference size grow over time, what could we call this evolution pattern?
