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  • Topic: Finch, Darwin's finches, Charles Darwin
  • Pages : 6 (1776 words )
  • Download(s) : 26
  • Published : February 25, 2013
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This is a lab report is on the evolution of finches on Darwin Island and Wallace Island. I wanted to experiment with certain variables to see how the birds on these islands would be affected. By examining small populations of finches on these islands, I would like to see the outcome of beak size and population as the finches on the island evolve with different controlled environments. The environment on the islands can be changed by island size, precipitation, and diet. What will happen to the birds over 100, 200, or 300 years?

I think that if the precipitation on the island is higher then the seeds will be softer and the birds will evolve smaller beaks to eat the softer seeds. If the seeds are harder the beaks of the birds will be stronger and larger because of the force needed to open the harder food source. I assume the amount precipitation will affect the food source and thus the beak size as well. The materials needed for this experiment are a computer, Internet access, and access to the EvolutionLab via the student website.

The first step to my experiment is opening the EvolutionLab link on the student materials page. Once that link is selected, the EvolutionLab will open and a separate applet window will appear taking you to the actual EvolutionLab. On the left of the applet window there are tabs listing the different variables available for the experiment. These variables are: beak size, variance, heritability, clutch size, island size, population, and precipitation. The dependent variables are the beak size and finch population. Beak size can be adjusted via slider bar on the bottom of the window. This will let you choose initial beak size from 10 mm to 30 mm. Controlled the same way is population (number of finches on the island), which can range from 50 to 600 finches initially. Variance is an independent variable that you can control from 0.0mm to 2.0mm. This will control the amount of variance between beak sizes from one bird to the next. Heritability is another independent variable that you can control from 0 to 1. Zero representing no genetic contribution, and 1 representing no environmental contribution. Other independent variables are clutch size (amount of eggs laid by female finch); a slider, which ranges from 2 eggs to 30 eggs, can control this. Last, precipitation (amount of rainfall), can range from 0 cm up to 100 cm, this will also determine the type of seeds that the finches will have to eat on the island. These variables and their input buttons are on the left side of the lab window, they when clicked, allowing you to adjust the parameters of that particular variable. Once all of the parameters are set to you’re desired settings you can click on the tab that reads “Done”. Clicking on the done tab sends you to the input summary screen where you can review the inputs you selected for your experiment. On the left sidebar you have “Change Inputs” button which takes you to the last page if you would like to make any changes to your inputs. Below that button is a button where you can choose the length of time for the simulation experiment; you may choose 100, 200, or 300 year intervals. Select the interval and click on the button that reads, “Run Experiment”. After you click on “Run Experiment” you will be taken to the output screen. At the output screen there are five tabs, which give you data on the results of the experiment. The field notes tab provides a table of the raw data on the population and mean beak size on each island, for each year. Beak size tab, presents data in a line graph, showing beak size over time for each island. Histograms tab shows a graph of total birds and relative beak sizes on each island. The horizontal line or x-axis shows beak size, and the vertical line or y-axis shows number of birds. The thin red and blue vertical lines represent the mean beak sizes for the surviving birds and the total birds respectively. There is a population tab,...
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