Artificial Selection Lab Mary Wuerth

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What types of selection are involved in evolution?  Natural selection  Ex. giraffes  Sexual selection  Ex. peacocks  Artificial selection  Ex. Domesticated dogs

Review Artificial Selection  Artificial selection is the intentional selection for and reproduction of individuals in a population that have desirable traits.  For many centuries, artificial selection has contributed to the development of food crops such as, broccoli, kale, fruits, gains, and the development of livestock such as cattle and chicken.

Lab: How does artificial selection affect plant height?  Question: How does artificial selection affect plant height?  Null Hypothesis: The artificial selection does not affect plant height.  Hypothesis 1: If we select for/cross pollinate only the tallest 10% of the plants, plant height will increase in the next generation. Now write down an alternative hypothesis, thumbs up when you are done!

Now let’s think about the experiment we are about to do 1. What would the data look like if the null hypothesis is supported? 2. What would the data look like if hypothesis 1 is supported? 3. What would the data look like if hypothesis 1 is rejected? 4. What would the data look like if your hypothesis is supported? 5. What would the data look like if your hypothesis is rejected?

Our Experiment: Hypothesis 1: If we cross pollinate the tallest 10% of the plants, the mean plant height in the next generation will increase.  We will grow fast plants from standard seed stock showing normal variation in height  On day 11, we will measure and record the height of each plant in both our notebooks and the spreadsheet provided  When these plants flower, only the tallest 10% of plants will be cross pollinated, these plants will be allowed to continue to grow and produce seeds

 Seeds will be harvested and planted to produce generation two.  On day 11 plant height in generation two will be measured and recorded in the spreadsheet provided  When these plants flower, only the tallest 10% of plants will be cross pollinated, these plants will be allowed to continue to grow and produce seeds Our Experiment:

Our experiment  Means and standard errors for plant height will be calculated for each generation, unpaired t test will be calculated on the means for the two generations NAME AND PLANT ID NUMBER GENERATION ONE HEIGHT IN MM UNPAIRE D T TEST justine justine 4205 justine 5200 justine 6160 justine 770 MICHAELA A180 MICHAELA B210 MICHAELA C180 MICHAELA D185 Sam a130 sam b164 sam c115 sam d165 sam e160 MEAN MAXIMUM HEIGHT 210 STANDARD DEVIATION STANDARD ERROR NAME AND PLANT ID NUMBER GENERATION TWO HEIGHT IN MM NATALIE A177 NATALIE B186 NATALIE C260 NATALIE D153 MICHAELA A180 MICHAELA B210 MICHAELA C180 MICHAELA D185 IZZY A230 IZZY B191 IZZY C283 IZZY D161 FMD A231 FMD B197 MEAN MAXIMUM HEIGHT 283 STANDARD DEVIATION STANDARD ERROR

How to measure plant height  Using the clear plastic rulers provided, measure from the base of the stem at the soil to the second leaf node.  Remember that a leaf node is the place on the stem where a leaf is attached.  Label the plant using the stakes provided with the height measurement  Enter all height measurements into the excel spreadsheet provided

Assessment  Using the class data in the spreadsheet and the handouts provided, you will construct a lab miniposter.  The miniposter will be evaluated according to the rubric we have used for all of our lab write ups.  You may use multiple “flaps” for your data section on your poster, if necessary  You will use a bar graph to plot the mean plant height for each generation (don’t forget your error bars! +/-2SEMs)

Have fun, and happy growing!