Evolution in Action Postlab Review

Page | 1 Postlab Review Part B Questions 1. a. What observations can you make about the overall shape of each graph? (Imagine that you are drawing a line that connects the tops of the horizontal bars.) The overall shape of each graph would be an outline of repeated hills. starting low and going high and then back low. 1.b. What do the shapes of the two graphs indicate about the distribution of beak depth measurements in these two groups of medium ground finches? The shapes of the two graphs represent a variety of beak depths , it also represents that they may cluster round depending on the similar depths. 2. Compare the distribution of beak depths between survivors and non-survivors. In your answer, include the shape of the distributions, the range of the data, and the most common measurements. The form of each of the graphs between survivors and non survivors are comparable by both taking the form of a hilly shape. The depths of medium ground finches that did not survive ranged between 7.5 and 11.25 in beak depth. The majority of non survivors possessed 8.5 or 9 mm beak depths with a total of 7 finches each. On the other hand, the survivors beak depths ranged between 8 and 11.25 mm. With the highest amount of survivors being 10 mm with a total of 8 birds. 3. Based on what you saw in the film, think about how changes in the environment may have affected which birds survived the drought. Propose a hypothesis to explain differences in the distribution of beak depths between survivors and non-survivors. After watching the video, it seems as though the birds with the bigger beaks were able to access more food. They were able to eat the bigger seeds due to the ability to crush them whereas the ones with the smaller beaks had a harder time. My hypothesis would be, Finches with bigger beaks are able to better adapt to a changing environment than finches with smaller beaks.

Page | 2 4.Let’s look in more detail at the mean beak depths in the two groups of birds to understand the meaning of standard deviation. a. How do the mean beak depths and standard deviations of the mean beak depths compare? The deviations between the survivors and non survivors were barely different. The mean depths for the birds that did not survive were 9.11mm. Whereas, the mean depths for the survivors were 9.67%, resulting in approximately 6% increase. b. If the standard deviations of the two samples were vastly different, what would you conclude about the two groups I would conclude the data to be spread out equally. Part C Questions Data Table 1. Beak Depths in Two Samples of Finches. Non-survivors Survivors 5-bird sample 15-bird sample 5-bird sample 15-bird sample Beak Depth (mm) Beak Depth (mm) Beak Depth (mm) Beak Depth (mm) Mean 8.78 Mean 9.11 Mean 9.78 Mean 9.56 s 1.15 s 0.98 s 1.06 s .90 5. Record the means and standard deviations for each sample of survivors and non-survivors from Figure 1 in Part B (50 birds) and Data Table 1 (5 and 15 birds) in Data Table 2 below. Data Table 2. Mean Beak Depths for 50-, 15-, and 5-finch Samples of Birds. Mean Standard Deviation 50-finch sample 15-finch sample 5-finch sample 50-finch sample 15-finch sample 5-finch sample Non-survivo rs 9.11 9.11 8.78 .88 .98 1.15 Survivors 9.67 9.56 9.78 .84 .90 1.06

Page | 4 Part D Questions: Graph 1: Graph 2:

Page | 5 9. Based on the graphs you have drawn, how does wing length compare between survivors and non-survivors? What about body mass? The graphs indicate that the finches with greater body mass and wing length had a more probable chance at surviving than those of less. 10. What do the results illustrated by your graphs indicate about the effects of the drought on birds with particular wing lengths and body masses? The results indicate that the birds with greater body mass and longer wings were able to adapt to the changing environment more than the smaller birds. 11. The Grants say in the film that a key trait that made the difference in survival for the birds during the drought was beak depth. Is that conclusion consistent with the data presented in this activity (including Part B)? Grants conclusion that beak depth was a key trait in the ability to survive in not a consistent trait of the data with this activity. Reason being is because the data presents the wing length as being another key trait that assisted in the finches means of survival rather than beak length being solely the reason.