Finch Beak Size Variation - ES - LS - Inheritance and Variation

Last updated 4 months ago

5 Nsɛmmisa

Hyɛ no nsow a efi ɔkyerɛwfo no hɔ:

Directions: Use the information provided and your knowledge of Life Science to answer the following questions. Show all work where necessary.

Akwankyerɛ

Directions: Use the information provided and your knowledge of Life Science to answer the following questions. Show all work where necessary.

Ɛhia

DOK 3

3-LS3-1

Ɛhia

DOK 2

3-LS3-1

Ɛhia

DOK 1

3-LS3-1

Ɛhia

DOK 2

3-LS3-2

Ɛhia

DOK 3

3-LS4-2

Finch Beak Size Variation

On the Galápagos Islands, populations of Darwin’s finches show remarkable differences in beak size and shape. These differences are inherited from parents but also vary within each generation, helping finches survive on islands with different food sources.

Researchers Peter and Rosemary Grant have studied finch populations on Daphne Major for over 40 years. They discovered that beak traits are heritable - offspring beak size closely resembles that of their parents - yet variation always exists within the group.

Example Findings

Finch parents with larger beaks usually have offspring with larger beaks.
Finch parents with smaller beaks tend to produce smaller-beaked offspring.
However, in any generation, there is a range of beak sizes, not all identical, even among siblings.

Environmental events, like droughts, can shift which traits are favored - smaller seeds favor small beaks, and tough seeds favor large beaks.

Data from field measurements show this pattern:

Parent Beak Depth (mm)	Average Offspring Beak Depth (mm)
8.0	7.9
8.5	8.3
9.0	8.8
9.5	9.3
10.0	9.7

Even with strong inheritance, variation ($\pm 0.5 \, \text{mm}$) exists within each offspring group. This variation provides the raw material for natural selection and is clear evidence that traits are both inherited and variable within a species.

Table 1.

Parent Beak Depth (mm)	Offspring Beak Depth (mm)	Parent Beak Depth (mm)	Offspring Beak Depth (mm)	Parent Beak Depth (mm)	Offspring Beak Depth (mm)	Parent Beak Depth (mm)	Offspring Beak Depth (mm)	Parent Beak Depth (mm)	Offspring Beak Depth (mm)
8	8.15	8.5	8.07	9	9.53	9.5	9.00	10	10.07
8	7.83	8.5	8.07	9	8.69	9.5	10.23	10	9.79
8	8.22	8.5	8.42	9	8.83	9.5	9.29	10	9.64
8	8.66	8.5	7.34	9	8.09	9.5	8.77	10	9.55
8	7.78	8.5	7.44	9	8.53	9.5	9.71	10	8.96
8	7.78	8.5	8.02	9	8.86	9.5	8.69	10	9.34
8	8.69	8.5	7.79	9	8.22	9.5	9.40	10	9.47
8	8.28	8.5	8.46	9	8.99	9.5	8.32	10	10.23
8	7.67	8.5	7.85	9	8.50	9.5	8.64	10	9.70
8	8.17	8.5	7.59	9	8.65	9.5	9.40	10	8.82

Graph of Information - Figure 1.

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Graph of Information - Figure 2.

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Ɛhia

Make a claim, provide the evidence, and explain your reasoning for the statement:
“Beak size in finches is inherited from parents, but variation exists in every generation.”
Claim:
Evidence:
Reasoning:

DOK 3

3-LS3-1

Ɛhia

Refer to Table 1 in the Finch Beak Size Variation resource.
Describe the relationship between parent beak depth and offspring beak depth.

DOK 2

3-LS3-1

Ɛhia

Which statement best describes what the data in Table 1 show?

All finch offspring have identical beak sizes.

Larger-beaked parents tend to have larger-beaked offspring, but not all offspring are the same.

Beak size is random and not related to parents.

Offspring always have smaller beaks than parents.

DOK 1

3-LS3-1

Ɛhia

During a drought, seeds become harder and larger. What environmental factor could influence beak size in the next finch generation?

The abundance of soft seeds makes beaks smaller.

Tough seeds may favor finches with larger, stronger beaks that can open them.

The climate causes finches to lose their beaks completely.

The drought has no effect on beak traits.

DOK 2

3-LS3-2

Ɛhia

Explain how variation in beak size might give some finches an advantage when food resources change on the island.

DOK 3

3-LS4-2

Finch Beak Size Variation - ES - LS - Inheritance and Variation

Finch Beak Size Variation

Table 1.

Graph of Information - Figure 1.

Graph of Information - Figure 2.

Make a claim, provide the evidence, and explain your reasoning for the statement:“Beak size in finches is inherited from parents, but variation exists in every generation.”Claim:Evidence:Reasoning:

Refer to Table 1 in the Finch Beak Size Variation resource.Describe the relationship between parent beak depth and offspring beak depth.

Which statement best describes what the data in Table 1 show?

During a drought, seeds become harder and larger. What environmental factor could influence beak size in the next finch generation?

Explain how variation in beak size might give some finches an advantage when food resources change on the island.

Finch Beak Size Variation

Table 1.

Graph of Information - Figure 1.

Graph of Information - Figure 2.

Make a claim, provide the evidence, and explain your reasoning for the statement:“Beak size in finches is inherited from parents, but variation exists in every generation.”Claim:Evidence:Reasoning:

Refer to Table 1 in the Finch Beak Size Variation resource.Describe the relationship between parent beak depth and offspring beak depth.

Which statement best describes what the data in Table 1 show?

During a drought, seeds become harder and larger. What environmental factor could influence beak size in the next finch generation?

Explain how variation in beak size might give some finches an advantage when food resources change on the island.

Make a claim, provide the evidence, and explain your reasoning for the statement:
“Beak size in finches is inherited from parents, but variation exists in every generation.”
Claim:
Evidence:
Reasoning:

Refer to Table 1 in the Finch Beak Size Variation resource.
Describe the relationship between parent beak depth and offspring beak depth.

Make a claim, provide the evidence, and explain your reasoning for the statement:
“Beak size in finches is inherited from parents, but variation exists in every generation.”
Claim:
Evidence:
Reasoning:

Refer to Table 1 in the Finch Beak Size Variation resource.
Describe the relationship between parent beak depth and offspring beak depth.