Lab – Variation of Traits Normal Distribution

Look around the room? Do we all look alike? Somewhat, but there is a variety of traits or variation of traits. What are some traits that show variation? We’re going to look at two of your traits: How far apart are your eyes? How quick your reaction time is? And a trait in another species: sunflower seeds

Is there an advantage to having you eyes a certain distance? Is there an advantage to having a quicker reaction time?

Date: Title: Variation of Traits Within Species Purpose: To determine if there is variation within species and if so, if there is a pattern to the variation. Hypothesis: Based on my observations, there (choose: is or is not) variation within species. If you believe there is variation, predict the pattern, either: There is no pattern to this variation because . . . There is a pattern . . . (and explain, what is the pattern like)

Date: 4/8/15 Title: Variation of Traits Within Species Procedure: Use online human reaction test to record our average reaction time. With a partner measure eye distance using yarn. Put data into spreadsheet on chromebook. Count the stripes on sunflower seeds and put them into the correct cylinder. With a partner use a meter stick to collect reaction time. Do three trials and collect the average. Hold fingers an inch apart at the 0 mark. Put data on board. Why are we doing three trials and calculating the average?

Station #1 Sort the sunflower seeds based on how many stripes they have. Do not count the two white stripes on the sides. Count up all of the stripes front and back and put in corresponding cylinder. Each person sort 100 seeds Collect class data and graph Don’t count no stripes 3 stripes (plus stripes on other side)

Station #2 – Eye Distance (cm) Work with a partner Use the yarn to measure the distance between your partner’s outer corners of eyes. Hold the yarn about an inch away from their face and put fingers where the corners of the eye are. Measure the distance on the yarn with a ruler.

Station #3 – Human Reaction Time Human reaction time: The distance a meter stick drops before you can catch it will serve as our measurement of reaction time. Partners alternate being experimenter and subject. a. Subject: Sit with dominant arm resting on table, hand extending past edge with thumb and forefinger parallel to ground and 4 cm apart. Check this distance with a ruler and keep uniform through each trial or results may be affected. b. Experimenter: 1) Hold meter stick vertically between subject’s thumb and index finger, bottom of meter stick (0 cm) even with index finger and thumb. 2) Without warning drop stick. c. Subject: Attempt to catch the meter stick between your thumb and index finger. d. Experimenter: Note the number of centimeters (to nearest .1 cm) the meter stick dropped and record. e. Repeat 2 more times and record. Calculate the average of the 3 trials and record on the board. f. Subject and experimenter now switch roles and repeat steps a-e.  

Station #4 – Human Reaction Time Using your smartphone or a chromebook, google search: Human Reaction Time. Click on Link for “Human Benchmark”. Do five trials and record your average reaction time in milliseconds. Record in your data table.  

Make these two data tables: My Data Eye Distance (cm) Average Reaction Time (ms) Average cm Dropped Class Data for Average cm Dropped Cm Dropped # of Students 0-4.9 5-9.9 10-14.9 15-19.9 20-24.9 25-29.9 30-34.9 35-39.9

Draw Graph – What kind of graph? Histogram X-axis: cm dropped Y-axis: number of students Draw a curved best of fit line Find your reaction time and put an x on the line. How does your reaction time compare to other students in the class? Class Data for Average cm Dropped Cm Dropped # of Students 0-4.9 5-9.9 10-14.9 15-19.9 20-24.9 25-29.9 30-34.9 35-39.9 Histograms used to plot frequencies

Graph sunflower seeds X axis: stripes 0-14 Y axis: ml of sunflower seeds Draw a curved: Best fit line

Interpret your graph 1. Look at your graph and the graph of finch beaks, how are they similar? How are they different?

Interpret your graph 2. Based on these graphs, what are the common patterns or trends in the variation of traits?

Interpret your graph 3. Do you think the degree of variation you observed in this lab is unusual or common?

Normal Distribution = Bell Curve

Normal Distribution = Bell Curve For example, adult male heights are on average 70 inches  (5'10) with a standard deviation of 4 inches. Adult women are on average a bit shorter and less variable in height with a mean height of 65  inches (5'5) and standard deviation of 3.5 inches. If we took a large sample of men and women's heights and graphed the frequency of the heights we'd see something like the following: Source of height graphs: http://www.usablestats.com/lessons/normal

Normal Distribution = Bell Curve For example, adult male heights are on average 70 inches  (5'10) with a standard deviation of 4 inches. Adult women are on average a bit shorter and less variable in height with a mean height of 65  inches (5'5) and standard deviation of 3.5 inches. If we took a large sample of men and women's heights and graphed the frequency of the heights we'd see something like the following: Source of height graphs: http://www.usablestats.com/lessons/normal

Normal Distribution = Bell Curve For example, adult male heights are on average 70 inches  (5'10) with a standard deviation of 4 inches. Adult women are on average a bit shorter and less variable in height with a mean height of 65  inches (5'5) and standard deviation of 3.5 inches. If we took a large sample of men and women's heights and graphed the frequency of the heights we'd see something like the following: Source of height graphs: http://www.usablestats.com/lessons/normal

Darwin’s Explanation of How Evolution Occurs 4. Why doesn’t this graph look have the bell shape that the reaction time graph had? 5. If we measured eye distance for all of the students at this school, what do you think the graph would look like? 6. Where do you fall on this graph?

Darwin’s Explanation of How Evolution Occurs Insufficient Data - If more data was collected you would see a normal distribution/Bell Curve This is why you need a large sample size (lots of data). Otherwise you can’t see accurate trends.

Darwin’s Explanation of How Evolution Occurs Variations – differences between individuals of one species Variation is the rule, not the exception!

Conclusion questions restate purpose, explain your hypothesis with data from the lab and answer the following questions. 1. Humans have 2 eyes a. IS there an advantage to having 2 eyes vs 1 b. Is there an advantage to having eyes a distance apart instead of close together? Explain

2. Might the number of stripes on a sunflower seed affect the ability of the plant to survive and reproduce 3. On the human benchmark test were did you fall on the graph compared to 40000 other people? What is the shape of that graph? Does reaction time have an effect of a human to survive and reproduce? Explain 4. Explain the pattern of variation of traits 5. Why do you think variation of traits is required for evolution?