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Zack Brown Anthropology 1020 Signature Assignment: Darwin’s Finches Introduction Darwin’s Finches are a group of closely related birds, 14 species with the same common ancestor on the Galapagos Islands (Soons, 1093) . The birds are referred to as called Darwin’s Finches because Charles Darwin famously collected them on his voyage to the Galapagos Islands as he was developing the theory of evolution by natural selection. The story of him finding the birds and immediately noticing the variation of their beaks is apocryphal, but has come to symbolize the development of the theory of natural selection in the way that an apple falling on Newton’s head symbolizes the development of the theory of gravity. The Galapagos Islands are an extraordinary playground of natural selection. Darwin’s finches are important and are still heavily studied today. The Earthwatch Institute summed up the finches’ importance well: “These finches are considered to be the world’s fastest-evolving vertebrates because their appearance and behavior quickly adapted to this closed and rapidly changing environment” (Darwin’s Finches and Natural Selection). The finches’ variety of beak type shows the way the finches have adapted to their environmental conditions. Darwin would later write this about the finches, "Seeing this gradation and diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends” (Charles Darwin and Evolution). The wild variation in beak type among the closely-related finches is the topic of much scientific research and testing. One study I read, Mechanical Stress, Fracture Risk and Beak Evolution in Darwin’s Ground Finches (Geospiza), investigates the “fracture-avoidance” hypothesis. The fracture-avoidance hypothesis is essentially that the ground finches (Geospiza) have developed wider and taller beaks mainly for the purpose of fracture avoidance (Soons, 1093)—i.e., basically the functionality and durability of their beak in the hard environment. To test their hypotheses, they developed “finite-element models” (FEMs) of the upper beak in ground finches (1094), collected, dissected, and CT-scanned several specimens, including the G. fortis, G. fuliginosa and G. scandens. The tests supported their hypothesis that “tall and wide” beaks handle pressure better and are more conditioned for fracture avoidance: “Tall and wide beaks seen in G. fortis, G. fuliginosa and G. magnitrosis are seen to distribute the load applied to the beak with lower peak stress values” (1096). The data reinforced their hypothesis that beak morphology “should evolve in concert with the force generating capacity of the jaw adductors through selection for the capacity to avoid structural failure under conditions of increased muscle and food reaction force” (1097). In class, we’ve been studying evolution by natural selection, and performed our own little experiment to demonstrate adaptive success in natural selection as seen with Darwin’s Finches beak types. The experiment itself is simple: using a variety of beak apparatus, each student competed against his peers to pick up as many sunflower seeds as she could and place said sunflower seeds into the apaper cup. There were five rounds. At the end of each round, the seeds were counted up, and the three birds/students with the lowest amount of seeds were sent into Loser’s Corner, and the top three seed gatherers were sent into the Winner’s Corner. The most effective beaks—the beaks with the most fitness—would replace the least effective beak and quickly grow and become the dominant species. When a bird/student lost, this would represent her beak not being a favorable trait, and therefore would being passed on to the next generation, and that species would go the way of the dodo. My initial hypothesis for the experiment was that the clothespin beaks would increase in frequency as the experiment went on. My rational was that the clothespin would be effective at picking up sunflower seeds, and would be favored by natural selection. My rational for this hypothesis was that the clothes pin beak had an inherent advantage for collecting resources, i.e., the clothespin seemed like an apt tool for picking sun flower seeds off a desk and placing them in a paper cup at a clip faster than the completion. Materials and Methods Our experiment included sunflower seeds, paper cups, and several variations of “beak” types in order to test which would be the most successful and have the most adaptive success. The beak types were: tongs, clothespins, chopsticks, binder clips, tweezers, chip clips, large hairclips, and, introduced as a mutation in the third round, a small hairclip. Also, willing volunteers would be necessary to recreate the experiment. The “beaks” or beak-like apparatuses, were distributed to the students (one student per beak). The base level of our experiment introduced an environment of 2 tongs, 5 clothes pins, 5 chopsticks, 5 binder clips, 5 tweezers, 5 chip clips, 5 large hairclips. A single small hairclip was introduced in round 3. The sunflower seeds had been distributed unevenly, more or less randomly. In a later round, more sunflower seeds were introduced into the environment. It had been a good season. There could have also been a drought; this was done to represent selective pressures, the environments effect on the fitness of traits. Results Beak Types Beginning Round 1 Round 2 Round 3 Round 4 Round 5 Tongs 2 3 3 3 3 3 Clothes Pins 5 5 7 8 9 10 Chopsticks 5 5 4 3 2 1 Binder clips 5 3 3 1 1 1 tweezers 5 5 5 5 5 5 Chip clips 5 2 6 6 8 9 Large hairclip 5 5 5 5 4 3 The most favorable beak was the clothespin. The beaks most suitable to the gathering the seeds quickly increased in number. The clothespins and chip clips were the most successful beaks, clothes pins having the greatest, finishing with 10 clothespin. Several species just got by throughout the experiment—passing on their beaks to the next generation, but not exactly flourishing. The tongs (the most surprising variation began with 2 tongs, finished, somehow, with 3); the tweezers started with five members of its species and finished with five members of its species. Three species suffered severe declines: the chopsicks—started with 5 and ended with 1—the binderclips, started with and ended with 1 surviving member of the species, and the large hairclip, started with five and ended with 3 surviving members. The small hairclip mutation, which happened in round three, turned out to be not a favorable mutation at all: the small hairclip went extinct by the end of the game, lost forever, not but a footnote in history. 12 10 Tongs Clothes pins 8 Chopsticks Binder Clips 6 Tweezers Chip Clips 4 Large Hairclip Small Hairclip 2 0 Beginning Round 1 Round 2 Round 3 Round 4 Round 5 Frequency of beak success Conclusion My hypothesis that the clothes pins would increase in frequency was supported by the experiment. Our data shows that clothe pin was indeed a favorable trait; it consistently improved in frequency after the second round, and the clothespin had doubled in number by the final round. There were some outside factors that the experiment can’t account for, and more tests would have to be run with a different test group before the data could say which is really the most effective beak. For instance, the experiment was done on the honor system—there were no official observers or cameras. A test subject/bird could have simply lied about how many sunflower seeds they had gathered. Another outside factor to be considered is the variation of skill level in the test subjects, e.g. the chopstick beak might have fared better or worse depending on the student’s ability with chopsticks. The way the beaks are used by individuals would create interesting variations that, in the data of this single experiment, is hard to account for. There were also environmental factors that could yield different results. All the beaks were handed out in sequence, meaning that the chopsticks all sat next to each other, the clothespins inhabited one location, etcetera. The seeds could have been unfairly disturbed onto their desks. Running the experiment again with other students would likely yield very similar results— the most effective beak types are the most effective beak types—but there would be variations and anomalies. Discussion The scientific method is used to objectify facts. By identifying a problem or an unproven idea, proposing an hypothesis, accurately collecting and analyze data, and assessing whether the data supports or falsifies the hypothesis. The scientific method is an effective tool for analyzing a situation and trying to parse facts from baseless speculation. I would argue that most fields use the scientific method in some way or another. A detective, for example, uses the scientific method: she makes an assessment that is plausible—Mr. Blue did it in the dining room with a candle stick, whatever—then has to follow up on her hypothesis by further investigating the crime, collecting data, and piecing together clear facts. The detective would then have to make an assessment about whether the evidence supports her original hypothesis. This experiment demonstrated the scientific method because I proposed a hypothesis that was a plausible assumption (in this case, that clothespins would be an effective tool for picking up sunflower seeds), and tested the hypothesis by performing an experiment and gathering data. I then evaluated the data and assed that it supported my hypothesis. The theory of evolution by natural selection explains how characteristics are passed on from generation to generation. This activity demonstrated how favorable traits are passed on to the next generation while unsuccessful ones die out. Natural selection is cruel, if you had an unfavorable beak, you stood no chance. References: Soons, J., A. Herrel, A. Genbrugge, P. Aerts, J. Podos, D. Adriaens, Y. De Witte, P. Jacobs, and J. Dirckx. "Mechanical Stress, Fracture Risk and Beak Evolution in Darwin's Ground Finches (Geospiza)." Philosophical Transactions of the Royal Society B: Biological Sciences 365.1543 (2010): 1093-098. Web. "Charles Darwin & Evolution." Charles Darwin & Evolution. Web. 07 Feb. 2015. http://darwin200.christs.cam.ac.uk/pages/index.php?page_id=b6 "Darwin's Finches and Natural Selection in the Galapagos." Darwin's Finches and Natural Selection in the Galapagos. N.p., n.d. Web. 06 Feb. 2015. http://earthwatch.org/expeditions/darwins-finches-and-natural-selection-in-the-galapagos