Download ePortfolio Signature Assignment Natural Selection

Nicole Murri
Anthropology 1020
Natural Selection Lab Report
Introduction
When Charles Darwin reached the Galapagos Island during his five year trip on the HMS
Beagle, he had noticed something specific about the finches of the island. From there he had examined
the fourteen different species that derived from a common ancestor. Darwin later wrote about what he
had learned from a specific bird, “The most curious fact is the perfect gradation in the size of the beaks
of the different species of Geospiza... Seeing this gradation and diversity of structure in one small,
intimately related group of birds, one might fancy that, from an original paucity of birds in this
archipelago, one species has been taken and modified for different ends.” (Grant, Rosemary & Grant,
Peter) Information had shown that morphology of the beak comes from the factors of natural selection
from the variation in food type, the availability of food, and the competition for food supply. From
observing certain birds it could be seen that birds that crush hard seeds from the base of their beaks
tend to have short, wide, and deep beaks. Birds that crush at the base and probe tend to have longer,
narrower and shallower beak type. From their research it can be moved to the focus on cracking ability
of a bird based on bite force and muscle placement. (Soons, Joris) From these observations brought
numerous hypotheses and tests to prove why and how they have adapted. From our natural Selection
Lab were able to simulate the possibilities of beak types and how they may be affected and adapted
due to food source and other factors.
Before the Natural Selection Lab, I had hypothesized from the list of beaks and the beak that I
had had, the small hair clip, that the small hairclips would do better than the large hair clips. From
what I could see from my hair clip, the legs were close together and I believed that they would be able
to pick up a sunflower seed with ease. From seeing the large hair clips I believed that there was a large
gap between each leg and it would allow the sunflower seed to fall between the gaps, making it much
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harder to collect a large amount of seeds. From this observation I had concluded that small hair clips
would do better than large hair clips.
Materials and Methods
For our experiment we used numerous tools to allow a number of possibilities. There were
thirty-five small, plastic cups, five chopsticks, five large hair clips, five tweezers, five small hair clips,
five binder clips, five chip clips, and eventually one tong. This experiment required thirty-five different
students. It also required a bag of sunflower seeds and appropriate tools to record the results each
round, and that includes a timer to keep track of the time for each round. In order to reenact this lab,
first the instructor should hand out small paper cups to ever individual in the classroom. From there
they must hand out the first five “beak” types, which were chopsticks. Next the instructor mush hand
out five clothes pins, five large hair clips, five tweezers, five small hair clips, five binder clips, five
chip clips. Each individual should have one cup and one of the seven different “beaks.” Next, the
instructor will scatter a handful of sunflower seeds on all of the desks. The instructor will set sixty
seconds on a timer and each student must attempt to pick up as many sunflower seeds with their beak
as possible and put it in their cup, if a student manages to pick up all of their sunflower seeds they are
allowed to move over to another desk and pick up other’s sunflower seeds. This is meant to replicate
how much food a bird can eat with their variation of beak. After the round the instructor will ask how
many sunflower seeds each student collected. The three students with the most will stand up and the
three students with the least will also stand up. Those with the least will give up there beak type and
will be given a new beak that it the same as one of those that had the most sunflower seeds. This is
meant to replicate that the favorable variations in beaks will fluctuate and those with least favorable
variations might decrease. During the beginning of the second round a new beak type will be added,
the tong, this was to show that new mutations can come and they may be favorable or unfavorable.
Each round continues with sixty seconds and continues the same way until the end. Our lab ended at
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the fifth round, after each round we counted how many beaks remained of each type and wrote it down
on the white board.
Results
From our results we can conclude that the chopsticks decreased from the beginning to the end.
Clothes pins decreased from beginning to end. Large hair clips increased from beginning to end.
Tweezers increased from beginning to end. Small hairclips remained constant until the last round and
then decreased. Binder clips decreased from the beginning to the end. Chip clips increased from
beginning to end. Tongs remained constant from beginning until the end. Overall, the three best “beak”
types were large hair clips, tweezers, and chip clips. The three that decreased the most were binder
clips, chopsticks, and clothes pins. However, the one beak type that more than doubled itself was
tweezers. It went from five to twelve through five rounds. This can conclude that the tweezer beak type
is the most favorable. From the graph and table on page six, the data demonstrates this information.
Conclusion
From the concluding information I can no longer support my initial hypothesis. Small hair clips
stayed at a constant rate and decreased by one during the final round. Even though this shows that
small hair clips could do well without comparison to others, it does show a risk of decreasing over a
long period of time. In comparison to the large hair clips, they were able to stay constant for a small
period of time but eventually slowly grow, this shows that large hairclips do better in comparison to
the progress of small hair clips. However there are possible outside errors that could impact the results
of the data. Each individual has a different method they used for picking up sunflower seeds, some are
much faster and more skilled, and this affects how many sunflower seeds they will pick up. That may
or may not have an effect on the numbers and has nothing to do with the actually clip. In addition,
there were only five rounds, over other rounds the numbers could have changed in opposite directions,
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or others could possibly get weak or hurt from their beak, which will affect the results. If this
experiment were replicated by a whole other group of students the results could possibly be completely
different. You have to take into consideration of tools, methods, time, preference, skill, and many other
factors. Because of these factors, if this experiment were replicated by other researcher I cannot say
that my results will be the same, and I cannot prove that my results are valid due to outside factors.
Discussion
The theory of evolution by natural selection comes from the idea of Charles Darwin and
Wallace. It is the idea that genetics change in the number of specific traits in populations. With this
there are four underlying assumptions. First, that there are natural biological variations occurring in
nature. Second, that there is inheritance. Third, there is competition. Fourth, those individuals with
favorable variations are more likely to survive and have more offspring, with this comes differential
reproductive success.
This activity stimulated the theory of evolution by natural selection because it demonstrated all
of the four underlying assumptions. It showed that there were natural variations from the eight
different beak types. From the loss of beak types and gaining of beak types of each round it was meant
to demonstrate the passing on of traits from one bird to another and show the loss of bird type when it
didn’t get enough food, which ties in with competition for food and reproduction. The lab showed that
tweezers were growing in numbers and changing the population of bird to the more favorable
characteristic. The frequency of tweezer beak type grew over the five rounds. There is beak variation
in birds, some are favorable, some are not, but tweezer beak type was a favorable variation. This
showed that tweezer beak type is passed on from parent to offspring. In every generation there are
more birds than can survive, however; birds with tweezer beaks are more likely to survive and have
more offspring.
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Works Cited:
Grant, Rosemary B., and Peter R. Grant. “BioScience.” What Darwin’s Finches Can Teach Us about the
Evolutionary Origin and Regulation of Biodiversity. Oxford Journals, n.d. Web. 06 Feb. 2016
Soons, Joris, Anthony Herrel, Annelies Genbrugge, Peter Aerts, Jeffrey Podos, Dominique Adriaens, Yoni De
Witte, Patric Jacobs, and Joris Dirckx. “Mechanical Stress, Fracture Risk and Beak Evolution in
Darwin’s Ground Finches (Geospiza).” Philosophical Transactions of the Royal Society B: Biological
Sciences. The Royal Society, 12 Apr. 2010. Web. 06 Feb. 2016.
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Beak Type:
Chopsticks
Clothes Pins
Large Hair
Clips
Tweezers
Small Hair
Clips
Binder Clips
Chip Clips
Tongs
Total:
Natural Selection Lab Data Table
Begin R1
R2
R3
5
5
4
3
5
4
4
2
5
5
6
7
R4
2
2
7
R5
2
2
7
5
5
7
5
8
5
10
5
11
5
12
4
5
4
4
4
34
34
2
5
1
35
2
5
1
35
2
5
1
35
2
5
1
35
14
\
Natural
Selection
Lab Graph
12
10
Chipsticks
8
Clothes Pins
Large Hair Clips
6
Tweezers
4
Small Hair Clips
Binder Clips
2
Chip Clips
Tongs
0
Beginning
6
R1
R2
R3
R4
R5