Name: ________________
Aim 46: NYS Beaks of Finches Lab
Date: _______________
1. Identify one adaptation, other than beak size and shape, a finch species might possess and state how that would aid in its
survival.
Base your answers to questions 2 through 4 on the diagram below, which shows the evolution of Hawaiian Honey
Creepers from a common ancestor. As their ancestors spread to new islands, they found a variety of different food sources.
Gradually, behaviors and beak structures evolved that took advantage of these different food sources, resulting in the
formation of several new species.
2. Some of the birds that could not compete with the honey creepers were successful living on other islands. State one reason
why this could be possible.
3. Other types of birds arrived at the islands, but they found it difficult to compete with the many forms of honey creepers.
Explain why the honey creepers were able to compete so successfully against the new arrivals.
4. Describe how the beaks of the bird species D, E, F, and J that eat fruits and seeds differ from the beaks of the bird species
that eat only nectar.
5. Which factor most likely contributed to the evolution of Galapagos Islands finches with different beak shapes?
1)
2)
3)
4)
similar climates on the different islands
competition between the finches for food
cloning experiments carried out by native people on the islands
increased rate of asexual reproduction
6. The first species of finch to inhabit the Galapagos Islands thousands of years ago was most likely an insect eater. Today,
finch species on these islands feed on a great variety of plants and animals. One early event that probably occurred that led
to this feeding diversity was that
1) members of the ancestral finch species had to decide if they would be better off feeding on seeds rather than on
relatively scarce insect species
2) some of the finch ancestors were born with beaks that were different from the beaks of other finches, and could eat both
insects and seeds
3) some members of the ancestral species that fed on insects began to die off, leaving few offspring
4) another species of bird, a seed eater, arrived on the islands and began to breed with members of the ancestral species
Base your answers to questions 7 and 8 on the information below and on your knowledge of biology.
There are two different species of finch that live on the same small island, species A and species B. Both species
successfully feed and reproduce on the island. Species A nests in pine trees and eats large seeds. Species B nests in
hollowed-out dead logs and eats small insects.
7. A third species of finch, species C, migrates to the island. It nests in pine trees and eats small insects. Predict what most
likely will happen to the populations of both species A and species B if species C successfully survives on the island.
Support your answer.
8. Both bird species A and species B can most likely survive on the same small island because they
1)
2)
3)
4)
use different resources and, therefore, they do not compete
mate with each other, keeping both populations constant
compete for food, but do not compete for shelter
eat the same food, but feed at different times of the day
9. Base your answer to the following question on the information below and on your knowledge of biology.
The differences seen in the beaks of the four species of finches are most likely the result of
1) gene expression and asexual reproduction
3) migration and the need to adapt
2) variation and natural selection
4) heredity and a diet of seeds
10. Studies of the finches of the Galapagos Islands have shown that
1)
2)
3)
4)
DNA will change to produce structures needed by birds to survive intense competition
a bird's beak changes annually in response to the type of food that is most abundant each year
natural selection occurs when there are scarce resources and intense competition
the beak of a finch will change if the environment of the bird remains stable
Base your answers to questions 11through 13 on the diagrams below and on your knowledge of biology. The diagrams
represent the variations in the beaks of finches in the Galapagos Islands and the relative abundance of food sources on a
certain island.
11.A bird count was done on the island and the small tree finch was found in all regions. State one possible reason why the
small tree finch is able to inhabit the entire island.
12.Explain why researchers would most likely observe the large ground finch in regions A and D on the island and not in
regions B and C.
13. Which histogram displays the relative abundance of small seeds in regions A, B, C, and D?
1)
2)
3)
4)
Base your answers to questions 14 and 15 on the information below and on your knowledge of biology.
The chart describes the beaks of various types of birds that live in a small island ecosystem containing flowering
land plants, aquatic plants, many small mammals, amphibians, and several species of trees.
14. Identify one kind of bird that would show an immediate decrease in number if the flowering land plants were destroyed by
an environmental change. Support your answer.
15. Identify the beak type that would be characteristic of predators of small mammals.
Base your answers to questions 16 and 17 on
the diagram below and on your knowledge of biology.
16. Several of the Galapagos Islands are inhabited by grasshoppers, beetles, flies, bees, and butterflies. Finches that feed on
these consumers would have beaks adapted for
1) probing, only
3) crushing or probing
2) probing or grasping
4) parrotlike feeding or grasping
17. Which two finches could temporarily occupy the same niche?
1)
2)
3)
4)
large ground finch and warbler finch
vegetarian tree finch and medium ground finch
large insectivorous tree finch and woodpecker finch
small insectivorous tree finch and cactus ground finch
18. Base your answer to the following question on Evolutionary changes have been observed in beak size in a population of
medium ground finches in the Galapagos Islands. Given a choice of small and large seeds, the medium ground finch eats
mostly small seeds, which are easier to crush. However, during dry years, all seeds are in short supply. Small seeds are
quickly consumed, so the birds are left with a diet of large seeds. Studies have shown that this change in diet may be
related to an increase in the average size of the beak of the medium ground finch.
The most likely explanation for the increase in average beak size of the medium ground finch is that the
1)
2)
3)
4)
trait is inherited and birds with larger beaks have greater reproductive success
birds acquired larger beaks due to the added exercise of feeding on large seeds
birds interbred with a larger-beaked species and passed on the trait
lack of small seeds caused a mutation which resulted in a larger beak
19. Base your answer to the following question on the information below and on your knowledge of biology.
In birds, the ability to crush and eat seeds is related to the size, shape, and thickness of the beak. Birds with larger,
thicker beaks are better adapted to crush and open seeds that are larger. One species of bird found in the Galapagos
Islands is the medium ground finch. It is easier for most of the medium ground finches to pick up and crack open
smaller seeds rather than larger seeds. When food is scarce, some of the birds have been observed eating larger seeds.
Explain this long-term change in beak characteristics using the concepts of:
• competition
• survival of the fittest
• inheritance
Base your answers to questions 20 through 22 on the information and diagram below and on your knowledge of biology.
Two species of finches found on a particular Galapagos island eat the seeds of a certain variety of plant. The
relative strength of their beaks is shown in the graph below.
20. One of the finch species has a slightly smaller, weaker beak. Is this species 1 or species 2? Support your answer with
information from the graph.
21. If the environment on the island changed and the seeds of more of the plants became harder to crack open, describe what
the graph might look like after many years have passed.
22. Select the point on the graph where beak strength of the two bird species is equal. Support your answer.
23. The diagram below represents the relationship between beak structure and food in several species of finches found on the
Galapagos Islands.
The different beak structures observed in the diagram are evidence of
1)
2)
3)
4)
different species of finches adapting to different environments over many generations
finches changing their beak characteristics so that they could feed efficiently
finch species with different beak structures coming to the Galapagos Islands from the mainland
finches mating with birds of other species and acquiring some of their traits
24. State two reasons why the large ground finch and sharp-billed ground finch could live on the same island but not compete
for food, even though they both eat mainly plant food.
25. Which statement is a basic assumption from The Beaks of Finches lab?
1)
2)
3)
4)
The type of beak indicates the type of food the finch eats.
Different birds have different songs.
Birds with larger beaks can find mates more easily.
Nesting behavior of finches is an inherited trait.
26. There are a number of islands in the Galapagos that these finches could possibly inhabit. Explain why each island would
not be expected to have all of the species shown.
27. Identify one species of finch that would most likely survive a sudden change in climate that destroyed seeds with small,
thin coverings, leaving only seeds with large, thick coverings. Support your answer.
Answer Key
BEAKS LAB PRACTICE
1.
2.
3.
4.
Adaptation: fast flight 7.
speed
— to escape
predators
Adaptation:
camouflage
— to hide from
predators
Adaptation: eyesight
— to locate food
Adaptation: mating
behavior (songs)
— to attract mates
– There were not
honey creepers to
compete with. –
There was enough
food for them on the
other island. – They
were well adapted to
the conditions on the
other island.
8.
1
9.
2
10.
3
11.
– The honey creepers
were well adapted to
the conditions on the
islands. – They had
evolved specific
skills/structures to
12.
find food on Hawaii.
– They were better
adapted than the new
arrivals.
– Fruit and seed
eaters have shorter,
thicker beaks. – The
nectar-eating birds
have longer, thinner
beaks. – Their beaks
are shorter.
5.
2
6.
2
– Both species A and
species B will
decrease in number,
since species C
competes with each
of them. – Species A
will compete with
species C for nesting
sites and species B
will compete for
food. Therefore, the
populations of both A
and B will decrease.
– Both will survive if
they are adequate
resources.
13.
–The small tree finch
eats mainly animal
food (insects), and
insects are found in
all four regions on
the island. –Insects
are found in all
regions.
–Large ground
finches prefer large
seeds. –Region B and
C lack the preferred
food source of large
ground finches,
which is large seeds.
–Large ground
finches have large
edge-crushing bills,
which are best for
eating the large seeds
found only in regions
A and D.
14.
—hummingbirds–no flowers
available to obtain
nectar from —
sparrows–no seeds
available for food —
birds with cracker
beaks–no seeds
available for food
15.
— shredder — sharp,
curved beak
16.
2
17.
3
18.
1
19.
20.
— They have the
weaker beak because
the majority of the
population is at the
low end of the graph.
— because it has a
weaker beak than
species 2, — except
where the two lines
overlap, More of
species 1 finches are
at the low-strength
end of the graph.
21.
— The curve for
species 1 may be
lower and shorter. —
The curve for species
1 may be eliminated.
— Both curves might
show an increase in
beak strength. —
There would be more
individuals in species
2 than in species 1.
— The curve for
species 1 would shift
to the right. answer
text here.
• Competition for
food would increase
as small seeds
became scarce. Birds
with larger, thicker
beaks would have a
better chance of
surviving when the
seeds were larger and
tougher to crack.
Birds with normal
thickness beaks
would be less likely
to survive.
22.
Reproduction of the
surviving birds, many
with the larger,
thicker beaks, would
produce more
offspring inheriting
the better adapted
beak type. Over time,
23.
this would lead to a
24.
large proportion of
the population having
the thicker beaks.
1
25.
[]
— At point C, the
beak strength has the
same value for both
species. — because
that is where the lines
intersect
wer text here.
1
They have different
beak structures. —
They might eat
different types of
plants. — They might
eat at different times
of day or night. —
They might live in
different areas of the
island.
1
Answer Key
BEAKS LAB PRACTICE
26.
Each island has its
own set of
environmental
conditions which
might not provide
food or shelter for
some of these
species. — Different
islands might have
different kinds of
food available. — too
much competition
27.
[]
— large ground finch
or medium ground
finch or small ground
finch or sharp-billed
ground finch because
it has a large crushing
beak and eats mainly
plant food —
large/small tree finch
or woodpecker finch
or warbler finch
because they don't eat
much plant food —
The warbler finch
eats only animal
food, so it would not
be affected.