Reminders<br />End of the semester is in a week a half!<br />Check your student view<br />Make an appointment with Miss Baker for make-up work!<br />Re-take for Natural Selection Exam Due Friday<br />
How we look at our data:<br />Did you all get measurements in cm?<br />If you didn’t take all your measurements in cm, can you easily compare heights using different units of measurement? Why or why not?<br />Did you all measure the apple circumferences the same way as neighboring groups from which you received data? How can you be sure?<br />Why were our graphs so problematic?<br />Do your graphs tell you anything with a degree of certainty about a population of spinach plants? Why or why not?<br />Can we learn about selective pressures from our small amount of data? Why or why not?<br />Why do we need a larger sample size?<br />
Let’s combine our data to make a class data set <br /><ul><li>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.
Re-evaluating the data:<br />What are some possible reasons (selection pressures) for the shape of the class spinach leaf graph?<br />How could we test these hypotheses?<br />
Definitions:<br />Adaptation-a trait that provides some type of advantage to organisms in the struggle for survival<br />Examples: speed, height, fur/skin color, claw length, flight<br />
Windows in back<br />3th Hour<br />Front White Boards<br />Ruska’s Desk<br />
Selection Pressure<br /><ul><li>Anything that can prevent an organism from passing on its genetic material
Some good examples are: predators, and competition for food, shelter, or mates</li></li></ul><li>Variation<br /><ul><li>Variety (or differences) of traits WITHIN A SPECIES.</li></ul>How do we get variation?<br />Genetic Shuffling in Anaphase I of meiosis<br />Mutation to DNA passed down to offspring (very rare!)<br />
Evolution is:<br />Genetic change in population over time.<br />These changes are seen in populations not in individuals<br />
Compare and Contrast Artificial Selection and Natural Selection<br />
Variation in traits exists<br />Breeder selects favorable traits in organism<br />Breeder mates animals with the favorable traits more than other organisms<br />Desired traits become more common in population<br />Variation in traits exists<br />Nature “selects” favorable traits in organism because some of these trait give a reproductive advantage<br />Organisms with favorable traits survive better and have more offspring<br />Traits that give a reproductive/survival advantage become more common in population<br />
Make some predictions:<br />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?<br />