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1. At-home activity: Selection on prey by a predator Print the figure below, or draw forty small circles on a sheet of paper. Fill in 10 of the circles with black ink, fill 20 with pencil (or a different color), and leave 10 of the circles white. These circles represent the prey species, and their colors represent variations (such as the ability to hide or to run fast) that may help them avoid being hunted and eaten by a predator. There are two alleles for the color gene, white (p) and black (q). The gray individuals are heterozygous. OOOOOOO Now, you will act as the predator and “hunt” the circles by drawing an X through 3 white circles, 2 gray circles, and I black circle. Begin by setting 30 seconds on the timer on your phone, and then start the countdown and your hunt. After each X that you draw, count to 10 in your head (about 3 seconds) before drawing the next X. If you have crossed out 3 white, 2 gray, and I black and you still have time left on the clock, repeat the same pattern until your 30 seconds is up. But remember to leave a little time (3 seconds or so) between each kill, or you will run out of prey before the 30 seconds is up. The number of each color that you hunt (3 white, 2 gray, 1 black) represents the advantage that each prey variation has. You can find and eat more white than black, because the white are less well adapted than the Focus a more me mam The number of each color that you hunt (3 white, 2 gray, 1 black) represents the advantage that each prey variation has. You can find and eat more white than black, because the white are less well adapted than the black. Based on the instructions given here, which color do you think is the best adapted to avoid predation? Write a hypothesis about what will happen to the frequency of each allele over time. When 30 seconds is up, see how many survivors are left (circles not crossed out are survivors). Use the number of survivors to calculate p and q as instructed below. Once you have p and q, you will calculate p, 2pq and ? and use those numbers to predict how many circles of each color there will be in the next generation, as instructed below. Once you have the new generation, repeat the hunting and the calculations in the same manner (step-by-step instructions are below). You will do this 3 times for 3 generations in total, and then you will graph your results in Excel. KCC students have free access to a web version of Excel. Click here for details. 2. Calculations In generation 1 (represented by the figure above), the allele and genotype frequencies are as follows: CWCW = Homozygous (white) CWCB = Heterozygous (gray) CFC – Homozygous (black) We will designate the white allele CW as p, and the black allele Casq. There are 40 individuals in the original population, which means there are 80 alleles total, since the individuals are diploid. 10 white circles 20 gray circles 10 black circles p=[(2 x 10)+20)/80 -0.5 p+q=1, therefore, q=0.5 If you are not sure why p and q are calculated in this way, please review the videos, the reading or the power point for this week before continuing. After the hunt, imagine that the following numbers of individuals survive. Record the number of survivors for generation 1 in the table in your lab report. Your actual number of survivors may be different from those below, but this example will show you how to do the calculations to figure out the proportions of colored circles O Focus cou how to do the calculations to the After the hunt, imagine that the following numbers of individuals survive. Record the number of survivors for generation 1 in the table in your lab report. Your actual number of survivors may be different from those below, but this example will show you how to do the calculations to figure out the proportions of colored circles for generation 2. 4 white circles 14 gray circles 8 black circles Now we must recalculate new p and q values (see below). Remember that the white allele is p and the black allele is q. p = [(2 x 4) + 14/52 = 0.423, and q = 1-0.420.577 p2 = (0.423)2 = 0.18 (round to two decimal places) q?- (0.577)2 = 0.33 (round to two decimal places) 2pq-2*0.423 * 0.577-0.49 (round to two decimal places) Now we construct a new population with 50 individuals using above p2, 2pq and q’ values. You will need to round up or down to the nearest whole number if the formula gives you a number such as 16.5. 9 white circles 24 gray circles 17 black circles (50 xp) = 9 (50 x 2pq) = 24 (round down) (50 x 9″) – 17 (round up) You will calculate p, q, p2, 2pq and using the number of survivors in your own trial. Record the values in the table in your lab report. Now draw generation 2 with the predicted values and do the hunt again. From the example above, we would use Focus E Now we construct a new population with 50 individuals using above p2, 2pq and q values. You will need to round up or down to the nearest whole number if the formula gives you a number such as 16,5. 9 white circles 24 gray circles 17 black circles (50 x P) = 9 (50 x 2pq) = 24 (round down) (50 x q2) = 17 (round up) You will calculate p, 4. p. 2pq and using the number of survivors in your own trial. Record the values in the table in your lab report. Now draw generation 2 with the predicted values and do the hunt again. From the example above, we would use 9, 24, and 17 and draw the circles as shown below. Remember, you should use the numbers you calculated from your own hunt rather than these example numbers. O ОООООООО Now hunt again, as you did before, and record the number of survivors in your lab report. Then calculate new allele and genotype frequencies. Based on the new allele and genotype frequencies you calculated, construct a new population (generation 3) of 50 individuals. If you have time, repeat the experiment two more times for a total of 5 generations. It may be Based on the new allele and genotype frequencies you calculated, construct a new population (generation 3) of 50 individuals. If you have time, repeat the experiment two more times for a total of 5 generations. It may be difficult to see a trend and draw any conclusions about your hypothesis with only 3 generations Using Microsoft Excel, plot allele frequencies (p and q) and copy and paste your graph in to the lab report. Your graph may look similar to the graph below. In 3 or 4 sentences in your lab report, describe and interpret your graph. Do the results support your hypothesis? Change in allele frequencies 07 0.62 0.59 as .647 14 3 0.14 Alle Free 03 02 3 Focus
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