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Fitness and mutation in finches...

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Fitness and Mutation in Finches Abstract Natural selection and speciation favor finches with larger beak depth, specifically in dry climates. We are trying to test if mutations that cause larger beak depths in finches will allow for greater survival and reproduction rates, and if ultimately speciation and natural selection favor finches with larger beak depth, specifically in dry climates.To test this, we gathered data about finches in the Galapagos that showed their beak depth, weight, fitness, and mutations. We found that there was a common mutation in the finches with a larger beak size. The mutation in the DNA sequence changed Leu to Phe and that coded for a larger beak size, ultimately causing a higher fitness. The research in this experiment is impactful because it shows that specific mutations affect the phenotypes of finches which ultimately affect their fitness rates. Introduction The Investigating Biology Lab Manual by Tarren J. Shaw and Donald P. French studied how the finches in the Galapagos Islands exhibited speciation in order to adapt to their environments and reproduce. The study in the manual sparked our interest and we decided to conduct an experiment that tested the effects of a specific mutation in the DNA on beak depth and fitness. We are investigating how mutations affect the fitness of finches in the Galapagos. In Rosemary Grant and Peter Grant’s study, the two studied how the El Nino event changed the habitat and number of plants on the island, causing there to be less food sources for the finches. They stated that finches who had specific mutations that allowed them to collect an abundance of a variety of seeds in dry climates were favored to survive. The Grants referred to this beneficial mutation as hybrid fitness. We saw how influential climate can be in the fitness of a finch so we wanted to conduct an experiment that tested the effects of specific DNA mutations on the fitness of a finch in dry climates. In another review conducted by G.H. Pyke, H.R. Pullman, and Eric Charnov, they studied the theory of optimal foraging. An optimal foraging model is used in attempts to predict the foraging behavior of animals. The models measure the effects of foraging through the amount of “currency” or energy spent. This study was extremely interesting because we wanted to see how finches with different phenotypes/ types of beaks used currency differently when collected food in dry climates. A study by Carl Wieland discussed the evidence supporting rapid post-flood adaptation. Due to natural events such as flooding, finches were dispersed across the Galapagos islands. On those islands, there were different amounts of seeds and types of seeds available, so over time, the finches living on those islands adapted different

traits like beak shape and size in order to collect food more efficiently. Selection occurred because the finches with more favorable traits survived and passed on their traits while finches with less favorable traits died off. Carl Wieland began to talk about results from an 18-year study conducted by Peter Grant saying that in years of drought, finches began to use the supply of small seeds so finches with large beaks became more favorable because they were able to eat all sizes of remaining seeds. This study was very interesting and we decided to test how limited seeds in a dry climate would affect the finches fitness and survival. Our hypothesis states that mutations that cause larger beak depths in finches will allow for greater survival and reproduction rates, and speciation and natural selection favor finches with larger beak depth, specifically in dry climates. We will know if our hypothesis is supported if the finches with the mutation have a larger beak size and a higher fitness in dry climates. We will know if our hypothesis is unsupported if the finches with the mutation do not have a larger beak depth and have a lower fitness in dry climates. Methods The independent variable is beak depth while the dependent variable is the fitness rates. The independent variable is the beak depth because that is the variable that is manipulated by the mutation and the dependent variable is the fitness rates because the fitness is dependent upon the beak depth. Our experimental group are the finches with and without the mutation Leu to Phe. Our control group is finch 0A because it is the first finch and does not have any mutations at all. This finch isolates the effects of the independent variable by getting a base for the beak depth without being affected by any mutations. We conducted our experiment well because we followed the steps in the instructional video. We gathered data and looked at every mutation in the DNA sequence. Since this experiment was so large, we conducted two different experiments and then used the results from both to make a conclusion. The first experiment required us to use different types of pliers to symbolize different shaped and depth of beaks and collect nuts in different climates. We used the entire class’ data which acted as multiple trials. The first experiment tested how climate affects fitness while the second experiment tested how mutations affect fitness. During the second experiment, we were given sixteen cards with data on beak depth, weight, and an amino acid sequence of each finch. We looked at the mutations and beak depth and determined what specific mutation caused the beak depth to be longer. To conduct the first experiment, all six of the lab groups in our class had a tray with an equal number of Brazil nuts, Almonds, Walnuts, and Hazelnuts. Each group was given a different type of plier to symbolize different shapes and depths of beaks. As soon as the timer began, each “finch” went to the trays and tried to collect as many nuts

of any kind as possible. The finches quickly began to learn that some finches are better suited for collecting certain nuts than others. After every minute, each group reported the number of nuts collected and we were told whether or not we survived and how many offspring was reproduced. After every few trials, the instructor would change the conditions and report the type of climate. In a dry climate, each tray will have less seeds and in a wet climate, each tray will have an abundance of seeds. In the final trials, a predator would walk around and come to a certain tray for a few seconds. While they were there, no finches were allowed to collect seeds. Instead of each group conducting multiple trials, we used data from the entire class to determine the relationship between climate and fitness. To conduct the second experiment, we were given sixteen cards. The cards had the beak depth, weight, number of surviving offspring in the last three mating seasons, changes in the DNA marker sequence from the BMP4 Gene, and the changes in the amino acid sequence of BMP4 protein. By using the information on the cards, we were able to find the specific mutation that codes for a larger beak depth. That mutation is Leu to Phe. This second experiment is used to determine the relationship between mutations and fitness. Since all of the information was the same, we did not need to conduct more than one trial. We graphed this data with a bar graph as well as a scatterplot to give our experiment a more specific analysis. Our bar graph shows the average beak depth versus the mutation Leu to Phe while the scatterplot shows the beak depth versus fitness. We decided to use these graphs because it was easier to compare the independent and dependent variables in a clear and concise way. The bar graph allowed us to see how the mutation of Leu to Phe in the amino acid sequence of the finches affected the average beak depth while the scatter plot allowed us to see how the different beak sizes affected the fitness of the finches. For our statistical analysis we decided to use the single factor ANOVA without replication because we wanted to test the significant differences between the survival rate in a normal climate and beak depth versus the survival rate in a dry climate and beak depth. Our alternative hypothesis is that finches with a larger beak depth will have a larger survival rate in a dry or normal climate while finches with a smaller beak death with have a shorter survival rate in a dry or normal climate. Our null hypothesis for this experiment would be that all beak depths of finches would have the same survival rate in both normal and dry climates.

Results The results from the data show that the larger the beak depth, the greater the fitness is. The results also show that if the mutation that changes Leu to Phe is present, the average beak size is larger. As shown in Figure 1.1, when the beak depth increases,

so does the fitness. This correctly shows how the fitness will increase as the beak depth gets larger. For figure 1.2, we show the mutation in the Leu gene. When the Leu gene mutates to Phe, the average beak depth increases. Because of this average beak depth increase with the mutation, we can conclude that the fitness will also increase because the beak depth is getting larger from the mutation. For the Anova: Single Factor the difference of variance and for beak depth and survival rate are shown witht eh P-Value and the variances.

Figure 1.1 “Fitness and Beak Depth” shows the differential of beak depth to fitness of finches.

Figure 1.2 “Mutation of Leu to Phe and Beak Depth” shows if the mutation is present or not, it correlated towards the beak depth.

Figure 1.3 shows the “Anova: Single Factor” and the difference of variance from beak depth and survival rate

Discussion Based on our data, our hypothesis is supported; mutations that cause larger beak depths in finches will allow for greater survival and reproduction rates, and speciation and natural selection favor finches with larger beak depth, specifically in dry climates. The p-value is less than 0.05 which shows that our alternative hypothesis is supported. We did test our hypothesis and discovered that a mutation in the Leu codon to Phe causes a larger beak depth. When dry climates occurred, the finches with this mutation were able to eat any type of seed they could find which gave them the ability to survive and reproduce unlike the finches who did not have the mutation and their small beak depth caused them to starve and have a low level of fitness. Our hypothesis was supported because the data shows that the mutation Leu to Phe causes a larger beak depth, and the data also shows that finches with larger beak depths have a higher fitness. An error that could have occurred was not conducting several trials per group. While we used class data as multiple trials, our results could have been even more accurate if each group conducted more trials and we had more data. Another error could have occurred in the second experiment, we came to the conclusion that the one specific mutation in the Leu gene to the Phe gene caused the larger beak depths. While the data we collected shows that our hypothesis is supported, multiple mutations could have contributed to the larger beak depths. Some of the finches who had the mutation still had a similar beak depth as the finches without the mutation which means that the mutation causing Leu to become Phe could have contributed to the larger beaks but may not be the only cause of larger beak depth.

If we were to conduct another experiment, we would examine every mutation and inspect the relationship between beak depth, fitness, and mutation to find an even more accurate conclusion. Also, because we were combining the results of two experiments into one conclusion, if another experiment was conducted, we would analyze the effects of beak depth, fitness, and mutation in every type of climate, perhaps, even one where predators were present. By analyzing the results in every type of climate, we would be able to see if having a longer beak depth causes a higher level of fitness in every environment or if a longer beak depth is only beneficial in dry climates. By testing this and analyzing every climate, we can get a better idea as to why certain finches have adapted differently than other finches in the Galapagos Islands. In Charles Rueffler, Johan A.J. Metz, and Tom J.M. Van Dooren’s study, they analyzed the effects of life cycle graphs in evolutionary dynamics. Their findings show certain traits that are prevalent across many life cycles. The results of their analysis are beneficial because they show that specific traits are essential in the fitness and reproduction of species. This study was very interesting because it showed the importance of just one trait in the survival and reproduction of a species. In our experiment we found that one specific trait -larger beak depth- attributed to a higher level of fitness. If we were to conduct another experiment, it would be interesting to study the effects of other traits of the finches on their fitness. George C. William studied the costs of reproduction as well as natural selection and found that individuals have reproductive value. Each organism used energy when obtaining food but if it gains more energy from the food it eats than it does using energy to obtain that food, it has a positive reproductive value. William suggested that some traits allowed for certain species to reproduce more than others which leads to higher levels of fitness and reproduction rates. His study was very interesting because in the experiment we conducted, we found that finches with larger beak depths expended more energy trying to collect more smaller seeds and didn’t receive a lot of energy per each nut. But, we found that when finches with larger beak depths collected and ate larger seeds, they received a lot of energy from them so even though they expended a lot of energy getting the seed, they also gained a lot more from the bigger seeds while they needed more smaller nuts to gain the same amount of energy. In Peter Grant’s study he explained ideas about natural selection. He explained that the finches of the Galapagos Islands all evolved from a common ancestor. This was interesting because in the second experiment we conducted, we were given a card that showed the finch that all other finches evolved from so we could compare the effects of mutations and evolution on the finches that evolved from the first finch. In our experiment, the alternative hypothesis would be rejected if the p-value level was below 0.05. Our p-value was accepted because our p-value was 0.439, so because it is less than 0.05, the alternative hypothesis was accepted.

Citations French, Donald P., and Tarren J. Shaw. Investigating Biology: A Laboratory Resource Manual.Fountainhead Press, 2016. Pyke, G. H., et al. “Optimal Foraging: A Selective Review of Theory and Tests.” The Quarterly Review of Biology, vol. 52, no. 2, 1977, pp. 137–154., doi:10.1086/409852. Grant, Peter R. “Natural Selection and Darwin's Finches.” Scientific American, vol. 265, no. 4, 1991, pp. 82–87., doi:10.1038/scientificamerican1091-82. Grant, B. Rosemary, and Peter R. Grant. “High Survival of Darwin's Finch Hybrids: Effects of Beak Morphology and Diets.” Ecology, Ecological Society of America, 1 Mar. 1996, onlinelibrary.wiley.com/doi/10.2307/2265625/full. Williams, George C. “Natural Selection, the Costs of Reproduction, and a Refinement of Lack'sPrinciple.” The American Naturalist, vol. 100, no. 916, 1966, pp. 687–690., doi:10.1086/282461. Wieland, Carl. “Darwin’s Finches.” Creation Ministries International | Creation.com, creation.com/darwins-finches....