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The richness and diversity of life raises two of the most profound questions in biology: How do new species form? And, why are there so many species?
The richness and diversity of life raises two of the most profound questions in biology: How do new species form? And, why are there so many species?
6. The Origin of Species - The Beak of the Finch
6. The Origin of Species - The Beak of the Finch
a. Watch the video below - 16 mins
a. Watch the video below - 16 mins
OriginSpecies-Finches_SD.m4v2. Examine the data in the accompanying Excel activity
2. Examine the data in the accompanying Excel activity
Try and explain what the data represents.
3. Have a brief class discussion about the data and identify some trends and patterns you see in the data:
3. Have a brief class discussion about the data and identify some trends and patterns you see in the data:
- Are all the birds of similar size?
- What measurements seem to vary the most from individual to individual?
- Why do you think the sample only includes adult birds?
- Do you see any differences between the group of finches that only lived until 1977 and the finches that lived to 1978 and beyond?
QUESTION: This is a sample of only 100 birds, but we know from the film that the Grants collected data on almost the entire population of medium ground finches on Daphne Major. Most researchers typically collect data from samples rather than the entire population. Why do you think that is? What are some advantages and disadvantages of using samples in research?
Figure 1
Figure 1
4. Complete Part B below.
4. Complete Part B below.
1. a. What observations can you make about the overall shape of each graph?
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?
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.
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.
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?
b. If the standard deviations of the two samples were vastly different, what would you conclude about the two groups?
5. Complete Part D below
5. Complete Part D below
******** Graph on graph paper ********
11. Based on the graphs you have drawn, how does wing length compare between survivors and non-survivors?What about body mass?
12. What do the results illustrated by your graphs indicate about the effects of the drought on birds with particular wing lengths and body masses?
13. 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)?
14. Explain why the Grants concluded that beak depth may have played a more important role in survival during the drought than wing length or body mass. Correctly use the terms natural selection, adaptation, and fitness in your answer.
15.Explain the role of variation in important traits (like beak depth) in a population for the survival of a species.
Classroom Activities
Classroom Activities
18 mins
18 mins
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