A Fishy Twist on Adaptations

Station 1 A Fishy Twist on Adaptations Introduction Does the coloration of an animal affect its chances for survival? Do feeding mechanisms alter an ...
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Station 1

A Fishy Twist on Adaptations Introduction Does the coloration of an animal affect its chances for survival? Do feeding mechanisms alter an organism’s chance of living? How could an organism’s reproductive strategy affect the individual? How could it affect the species? Throughout time, people have marveled at the vast diversity found in nature. Adaptations have led to the vast array of variation and have resulted in the enormous diversity among species. There are also pressures in the environment which can select for those organisms best suited for survival. These are called selective pressures; the adaptations that best help organisms in the environment will be favored and organisms possessing them would be favored for survival.

Procedure • Design an underwater habitat. What sources of food are there? What color is the habitat? What hiding places could there be? On poster paper, draw and color the habitat. • Draw a fish to live in this habitat. Choose specific adaptations for body shape and structure, jaw shape and structure, and coloration. Design, color, and cut out the fish. Tape it into its habitat. List and describe the fish’s adaptations. How does it move around? How does it catch and eat its food? How does it hide from predators? How does it signal to a mate of the same species? • Assign your fish a scientific name, including a genus (first name, capitalized) and species (second name, lower case). Both names should be italicized or underlined. • Answer Analysis Questions 1 & 2 • Next, place your fish in another group’s habitat. • Answer Analysis Questions 3–8

Analysis Questions

1) How is your fish adapted to the habitat in which it lives? 2) Which adaptations are most important to your fish’s survival in this habitat? 3) List and justify any adaptations that will limit the success of your fish in its new habitat. 4) List and justify any adaptations that will increase the success of your fish in its new habitat. 5) Using your answers from questions 3 and 4, predict what would happen over time to your fish species in the new habitat. Predict what would happen over time to the population of this fish species in the new habitat. 6) Which adaptation is most important for the survival of the individual fish? Please explain your reasoning. 7) Which adaptation is most important for the survival of the fish species? Please explain your reasoning. 8) What role do adaptations play in Darwin’s theory of Natural Selection? Please be specific.

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Station 2

Skull Morphology Introduction Over the course of evolutionary time, descendants become different from their ancestors. Animals that have a recent common ancestor often share more characteristics than animals that have a more ancient common ancestor. Traits that are similar to one another because they were inherited from a common ancestor are homologous traits. Your nose is homologous to a dog’s nose, because the last common ancestor of humans and dogs had a nose that was made of cartilage, located in the middle of its face, and was used for smelling. For the same reason, your nose is homologous to an elephant’s nose, even though they look very different! However, your nose is not homologous to a bird’s beak, because the last common ancestor of mammals and birds did not have a beak, and the bird’s beak and our nose are derived from different ancestral structures (the upper and lower beak of a bird are homologous to our jaws, as both structures are made up of the maxilla and mandible bones). How do we know what traits an ancestor had, since it doesn’t exist today? We use a tool called parsimony, which states that the simplest explanation is probably the correct one. Is it more likely that the last common ancestor of birds and mammals evolved a beak, and then mammals lost their beaks (two assumptions), or that the last common ancestor of birds evolved a beak (one assumption)? By observing different traits of animal skulls, homology can be inferred and used to make hypotheses about common ancestry.

Procedure • Examine the skulls and categorize them in terms of similarity. Determine which traits you will examine, and the criteria for placing the skulls in each category. • Form a hypothesis about common ancestry.

Analysis Questions 1) What criteria did your group use for categorizing the skulls? Make a list. 2) D  escribe the habitat you think each group of organisms (skull category) would be best adapted to living in and explain your reasoning. 3) Respond to the following questions for each skull category; you may also draw sketches to support your written explanations: What do you think the ancestor species of each group might have looked like? What do you think the ancestor species’ habitat was like? List the major differences there might be in skull morphology between the modern species and their ancestor species.

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Station 3

DNA Sequence Evolution Introduction DNA is important to the study of evolution for two related reasons. First, DNA contains all of the information that is required to make an organism, and that information is organized into units called genes. So an organism with a long beak has genes for making a long beak that are distinct in some ways from the genes for making a short beak. This hints at the second important quality of DNA—DNA is passed from parents to their offspring, and it changes over evolutionary time. The reason that long-beaked parents have long-beaked offspring is because they pass their longbeak genes to the next generation through the DNA in their sperm and eggs. Recall that in order for evolution to occur, variation among organisms must be heritable, or passed from parents to their offspring. Therefore, in order for evolution of morphological (body shape) and physiological (body chemistry) traits to occur, the DNA encoding those traits has to evolve as well. When a DNA sequence changes between a parent and its offspring, a mutation is said to have occurred. Mutations are mistakes that are made when DNA is being copied. Mutations can have three fates: 1. First, if a mutation is bad for the function of the gene, natural selection will prevent the organisms that have that mutation from successfully reproducing and passing along the mutation to future generations. Many mutations that are selected against in this way will never be seen by scientists, because the organisms that had them were sick or died very quickly without leaving offspring. We won’t look at this type of mutation today. 2. Second, if a mutation is neutral for the function of the gene, it may be passed along to future generations but will not be a special advantage. Neutral mutations arise and accumulate in DNA at an extremely slow rate. 3. Third, if a mutation is advantageous for an organism because it changes the function of the gene in a way that helps the organism to better adapt to its environment, it will be passed along to more members of future generations compared to a neutral mutation. When a gene accumulates a number of mutations that change its function, we have evidence that those are helpful mutations, and that the gene’s function is adapting in the species. By looking at the sequence of genes, we can infer the history of their adaptive changes to the environment. In this exercise, we are going to perform a McDonald-Kreitman Test in order to answer the question: Is the Adh gene of the fruit fly Drosophila evolving in an adaptive manner?

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Procedure • Look at the DNA sequences of the Adh gene from two species of Drosophila—one individual of Drosophila simulans (DsimC) and 5 individuals of Drosophila yakuba (DyakL, J, I, G, A). The sequences are divided into triplet codons. • Cross off all triplet codons where the sequence is the same in every individual in both DsimC and all of the Dyak sequences. These unchanged parts of the gene cannot tell us anything about how the gene evolved. • You should have 32 codons left where there are differences among the sequences. Next, sort these differences into this 2x2 matrix following these instructions: 1. Differences in the FIRST POSITION of a codon change the function of the gene. Differences in the LAST POSITION of a codon do not change the function of the gene. 2. Differences between the DsimC sequence and ALL of the Dyak sequences represent divergences between the two species that have been selected for by natural selection. Differences among the Dyak sequences represent new mutations that have not yet stood the test of time.

Among Dyak

Between Dsim and Dyak

Total

No change to function Change to function Total

• Now, add up the totals for the rows and columns of this matrix. What proportion of the total number of differences that change the function of the gene are divergences between Drosophila simulans and Drosophila yakuba? What proportion of the total number of differences that do not change the function of the gene are divergences between Drosophila simulans and Drosophila yakuba? IF YOU HAVE STATISTICS, YOU CAN PERFORM A G-TEST FOR INDEPENDENCE HERE.

Analysis Questions 1) W  hat does it mean that a greater proportion of the differences that change the function of the gene have stood the test of time, compared to the proportion of differences that don’t change the function of the gene? 2) T he gene Adh encodes the enzyme alcohol dehydrogenase, which is necessary for organisms to extract chemical energy from alcohol in their food. Fruit flies, as their name implies, live on rotting fruit, which produces alcohol when fermented by bacteria or yeast. What natural selective pressures might act on the gene Adh to favor changes in its function? What might you guess is different about the food of Drosophila simulans and Drosophila yakuba?

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1 10 20 30 36 DsimC A T G G C G T T T A C T T T G A C C A A C A A G A A C G T G A T T T T C DyakL A T G G C G T T T A C C T T G A C C A A C A A G A A C G T G G T T T T C DyakJ A T G G C G T T T A C C T T G A C C A A C A A G A A C G T G G T T T T C DyakI A T G G C G T T T A C C T T G A C C A A C A A G A A C G T G G T T T T C DyakG A T G G C G T T T A C C T T G A C C A A C A A G A A C G T G G T T T T C DyakA A T G G C G T T T A C C T T G A C C A A C A A G A A C G T G G T T T T C 37 40 50 60 70 72 DsimC G T T G C C G G T C T G G G A G G C A T T G G T C T G G A C A C C A G C DyakL G T G G C C G G T C T G G G A G G C A T T G G T C T G G A C A C C A G C DyakJ G T G G C C G G T C T G G G A G G C A T T G G T C T G G A C A C C A G C DyakI G T G G C C G G T C T G G G A G G C A T T G G T C T G G A C A C C A G C DyakG G T G G C C G G T C T G G G A G G C A T T G G T C T G G A C A C C A G C DyakA G T G G C C G G T C T G G G A G G C A T T G G T C T G G A C A C C A G C 73 80 90 100 108 DsimC A A G G A G C T G C T C A A G C G C G A C C T G A A G A A C C T G G T G DyakL A A G G A G C T G G T C A A G C G G G A C C T G A A G A A C C T G G T G DyakJ A A G G A G C T G G T C A A G C G G G A C C T G A A G A A C C T G G T G DyakI A A G G A G C T G G T C A A G C G G G A C C T G A A G A A C C T G G T G DyakG A A G G A G C T G G T C A A G C G G G A C C T G A A G A A C C T G G T G DyakA A A G G A G C T G G T C A A G C G G G A C C T G A A G A A C C T G G T G 109 120 130 140 144 DsimC A T C C T C G A C C G C A T T G A G A A C C C T G C T G C C A T T G C C DyakL A T C C T C G A C C G C A T T G A G A A C C C G G C T G C C A T C G C C DyakJ A T C C T C G A C C G C A T T G A G A A C C C G G C T G C C A T C G C C DyakI A T C C T C G A C C G C A T T G A G A A C C C G G C T G C C A T C G C C DyakG A T C C T C G A C C G C A T T G A G A A C C C G G C T G C C A T C G C C DyakA A T C C T C G A C C G C A T T G A G A A C C C G G C T G C C A T C G C C 145 150 160 170 180 DsimC G A G C T G A A G G C A A T C A A T C C A A A G G T G A C C G T C A C C DyakL G A G C T G A A G G C A A T C A A T C C A A A G G T G A C C G T C A C C DyakJ G A G C T G A A G G C A A T C A A T C C A A A G G T G A C C G T C A C C DyakI G A G C T G A A G G C A A T C A A T C C A A A G G T G A C C G T C A C C DyakG G A G C T G A A G G C A A T C A A T C C A A A G G T G A C C G T C A C C DyakA G A G C T G A A G G C A A T C A A T C C A A A G G T G A C C G T C A C C 181 190 200 210 216 DsimC T T C T A C C C C T A T G A T G T G A C C G T G C C C A T T G C C G A G DyakL T T C T A C C C C T A C G A T G T G A C C G T G C C C A T T G C C G A G DyakJ T T C T A C C C C T A T G A T G T G A C C G T G C C C A T T G C C G A G DyakI T T C T A C C C A T A C G A T G T G A C C G T G C C C A T T G C C G A G DyakG T T C T A C C C C T A T G A T G T G A C C G T G C C C A T T G C C G A G DyakA T T C T A C C C C T A T G A T G T G A C C G T G C C C A T T G C C G A G

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217 220 230 240 250 252 DsimC A C C A C C A A G C T G C T G A A G A C C A T C T T C G C C A A G C T G DyakL A C C A C C A A G C T G C T G A A G A C C A T C T T C G C C C A G C T G DyakJ A C C A C C A A G C T G C T G A A G A C C A T C T T C G C C C A G C T G DyakI A C C A C C A A G C T G C T G A A G A C C A T C T T C G C C C A G C T G DyakG A C C A C C A A G C T G C T G A A G A C C A T C T T C G C C C A G C T G DyakA A C C A C C A A G C T G C T G A A G A C C A T C T T C G C C C A G C T G 253 260 270 280 288 DsimC A A G A C C G T C G A T G T C C T G A T C A A C G G A G C T G G T A T C DyakL A A G A C C A T C G A T G T C C T G A T C A A C G G A G C T G G C A T C DyakJ A A G A C C A T C G A T G T C C T G A T C A A C G G A G C T G G C A T C DyakI A A G A C C A T C G A T G T C C T G A T C A A C G G A G C T G G C A T C DyakG A A G A C C A T C G A T G T C C T G A T C A A C G G A G C T G G C A T C DyakA A A G A C C A T C G A T G T C C T G A T C A A C G G A G C T G G C A T C 289 300 310 320 324 DsimC C T G G A C G A T C A C C A G A T C G A G C G C A C C A T T G C C G T C DyakL C T G G A C G A T C A C C A G A T C G A G C G C A C C A T C G C C G T C DyakJ C T G G A C G A T C A C C A G A T C G A G C G C A C C A T C G C C G T C DyakI C T G G A C G A T C A C C A G A T C G A G C G C A C C A T C G C C G T C DyakG C T G G A C G A T C A C C A G A T C G A G C G C A C C A T C G C C G T C DyakA C T G G A C G A T C A C C A G A T C G A G C G C A C C A T C G C C G T C 325 330 340 350 360 DsimC A A C T A C A C T G G C C T G G T C A A C A C C A C G A C G G C C A T T DyakL A A C T A C A C C G G C C T G G T G A A C A C C A C G A C G G C C A T C DyakJ A A C T A C A C C G G C C T G G T G A A C A C C A C G A C T G C C A T C DyakI A A C T A C A C C G G C C T G G T G A A C A C C A C G A C G G C C A T C DyakG A A C T A C A C C G G C C T G G T G A A C A C C A C G A C T G C C A T C DyakA A A C T A C A C C G G C C T G G T G A A C A C C A C G A C T G C C A T C 361 370 380 390 396 DsimC T T G G A C T T C T G G G A C A A G C G C A A G G G T G G T C C C G G T DyakL C T G G A C T T C T G G G A C A A G C G C A A G G G T G G A C C C G G T DyakJ C T G G A C T T C T G G G A C A A G C G C A A G G G T G G A C C C G G T DyakI C T G G A C T T C T G G G A C A A G C G C A A G G G T G G A C C C G G T DyakG C T G G A C T T C T G G G A C A A G C G C A A G G G T G G A C C C G G T DyakA C T G G A C T T C T G G G A C A A G C G C A A G G G T G G A C C C G G T 397 400 410 420 430 432 DsimC G G T A T C A T C T G C A A C A T T G G A T C C G T C A C T G G A T T C DyakL G G T A T C A T C T G C A A C A T T G G A T C C G T G A C T G G A T T C DyakJ G G T A T C A T C T G C A A C A T T G G A T C C G T G A C T G G A T T C DyakI G G T A T C A T C T G C A A C A T T G G A T C C G T G A C T G G A T T C DyakG G G T A T C A T C T G C A A C A T T G G A T C C G T G A C T G G A T T C DyakA G G T A T C A T C T G C A A C A T T G G A T C C G T G A C T G G A T T C

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433 440 450 460 468 DsimC A A T G C C A T C T A C C A G G T G C C C G T C T A C T C C G G C A C C DyakL A A C G C C A T C T A C C A G G T G C C C G T T T A C T C C G G C A C C DyakJ A A C G C C A T C T A C C A G G T G C C C G T T T A C T C C G G C A C C DyakI A A C G C C A T C T A C C A G G T G C C C G T T T A C T C C G G C A C C DyakG A A C G C C A T C T A C C A G G T G C C C G T T T A C T C C G G C A C C DyakA A A C G C C A T C T A C C A G G T G C C C G T T T A C T C C G G C A C C 469 480 490 500 504 DsimC A A G G C T G C C G T G G T C A A C T T C A C C A G C T C C C T G G C G DyakL A A G G C T G C C G T G G T C A A C T T C A C C A G C T C C C T G G C G DyakJ A A G G C T G C C G T G G T C A A C T T C A C C A G C T C C C T G G C G DyakI A A G G C T G C C G T G G T C A A C T T C A C C A G C T C C C T G G C G DyakG A A G G C T G C C G T G G T C A A C T T C A C C A G C T C C C T G G C G DyakA A A G G C T G C C G T G G T C A A C T T C A C C A G C T C C C T G G C G 505 510 520 530 540 DsimC A A A C T G G C C C C C A T T A C C G G C G T G A C C G C T T A C A C C DyakL A A A C T G G C C C C C A T C A C C G G C G T G A C C G C T T A C A C C DyakJ A A A C T G G C C C C C A T C A C C G G C G T G A C C G C T T A C A C C DyakI A A A C T G G C C C C C A T C A C C G G C G T G A C C G C T T A C A C C DyakG A A A C T G G C C C C C A T C A C C G G C G T G A C C G C T T A C A C C DyakA A A A C T G G C C C C C A T C A C C G G C G T G A C C G C T T A C A C C 541 550 560 570 576 DsimC G T G A A C C C C G G C A T C A C C C G C A C C A C C C T G G T G C A C DyakL G T G A A C C C C G G C A T C A C C C G C A C C A C C C T G G T G C A C DyakJ G T G A A C C C C G G C A T C A C C C G C A C C A C C C T G G T G C A C DyakI G T G A A C C C C G G C A T C A C C C G C A C C A C C C T G G T G C A C DyakG G T G A A C C C C G G C A T C A C C C G C A C C A C C C T G G T G C A C DyakA G T G A A C C C C G G C A T C A C C C G C A C C A C C C T G G T G C A C 577 580 590 600 610 612 DsimC A A G T T C A A C T C C T G G C T G G A T G T T G A G C C C C A G G T T DyakL A A G T T C A A C T C C T G G C T G G A T G T T G A G C C C C A G G T G DyakJ A A G T T C A A C T C C T G G C T G G A T G T T G A G C C C C A G G T G DyakI A A G T T C A A C T C C T G G C T G G A T G T T G A G C C C C A G G T G DyakG A A G T T C A A C T C C T G G C T G G A T G T T G A G C C C C A G G T G DyakA A A G T T C A A C T C C T G G C T G G A T G T T G A G C C C C A G G T G 613 620 630 640 648 DsimC G C C G A G A A G C T C C T G G C T C A T C C C A C C C A G C C C T C G DyakL G C C G A G A A G C T C C T G G C T C A C C C C A C C C A G C C C T C G DyakJ G C C G A G A A G C T C C T G G C T C A C C C C A C C C A G C C C T C G DyakI G C C G A G A A G C T C C T G G C T C A C C C C A C C C A G C C C T C G DyakG G C C G A G A A G C T C C T G G C T C A C C C C A C C C A G C C C T C G DyakA G C C G A G A A G C T C C T G G C T C A C C C C A C C C A G C C C T C G

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649 660 670 680 684 DsimC T T G G C C T G C G C C G A G A A C T T C G T C A A G G C T A T C G A G DyakL T T G G C C T G C G C C C A G A A C T T T G T C A A G G C C A T C G A G DyakJ T T G G C C T G C G C C C A G A A C T T T G T G A A G G C C A T C G A G DyakI T T G G C C T G C G C C C A G A A C T T T G T G A A G G C C A T C G A G DyakG T T G G C C T G C G C C C A G A A C T T T G T G A A G G C C A T C G A G DyakA T T G G C C T G C G C C C A G A A C T T T G T G A A G G C C A T C G A G 685 690 700 710 720 DsimC C T G A A C C A G A A C G G A G C C A T C T G G A A A C T G G A C T T G DyakL C T G A A C C A G A A C G G T G C C A T C T G G A A A C T G G A C T T G DyakJ C T G A A C C A G A A C G G T G C C A T C T G G A A A C T G G A C T T G DyakI C T G A A C C A G A A C G G T G C C A T C T G G A A A C T G G A C T T G DyakG C T G A A C C A G A A C G G T G C C A T C T G G A A A C T G G A C T T G DyakA C T G A A C C A G A A C G G T G C C A T C T G G A A A C T G G A C T T G 721 730 740 750 756 DsimC G G C A C C C T G G A G G C C A T C C A G T G G A C C A A G C A C T G G DyakL G G C A C C C T G G A G G C C A T C C A G T G G T C C A A G C A C T G G DyakJ G G C A C C C T G G A G G C C A T C C A G T G G T C C A A G C A T T G G DyakI G G C A C C C T G G A G G C C A T C C A G T G G T C C A A G C A C T G G DyakG G G C A C C C T G G A G G C C A T C C A G T G G T C C A A G C A C T G G DyakA G G C A C C C T G G A G G C C A T C C A G T G G T C C A A G C A C T G G 757 760 771 DsimC G A C T C C G G C A T C T A A DyakL G A C T C C G G C A T C T A A DyakJ G A C T C C G G C A T C T A A DyakI G A C T C C G G C A T C T A A DyakG G A C T C C G G C A T C T A A DyakA G A C T C C G G C A T C T A A

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Station 4

Analogous and Homologous Structures Introduction Structural evidence supports evolution. Skeletal structures that are similar suggest common ancestry. Those structures that are less similar suggest a more distant ancestry. Quadrupeds are animals that walk on four legs. The back legs and feet are called hindlimbs. Humans are bipedal (walk on two legs). By observing the skeletal structure and photos of various animal groups, one can identify what traits of the hind limbs might be adaptations of the animal to its particular mode of locomotion. The front legs are called forelimbs/forelegs. Since humans are bipeds their forelimbs are called arms and hands. Animals use their forelimbs for many different tasks, such as grasping, holding, digging, climbing, and running. In evolutionary terms, form fits function.

Procedure • Observe the various animal skeletons and/or photographs. • Look for any similarities and differences in structure.

Analysis Questions



1) Define the word homologous. 2) Define the word analogous. 3) List three similarities between the foot of a human and the foot of a bird. 4) For each of the following animals, describe the structure of the hindlimb and/or the forelimb and the function they serve: lion, hawk, horse, wolf, frog and mole. Example: Describe the foot of a red fox. The foot helps the animal to run, because it has pads on the feet and to hunt because it has sharp claws for digging and holding onto its prey. The bones are long and provide support for the animal’s body, helping it to run fast. 5) How are the wings of the bat, insect, and bird similar? How are they different? 6) Would you classify the wings of a bat, insect, and bird analogous or homologous? Explain your answer. 7) Besides the tasks listed in the introduction, for what other activities can animals use their forelimbs? 8) Compare the skeletal structure of all of the animals at this table. List five similarities between the animals. 9) For each animal, describe the main function of the forelimb and the hindlimb. What are they used for? 10) F or each forelimb, describe one feature that makes the hand well suited for its function. In other words, relate the structure to the function of the forelimb. Do the same for the hindlimb. 11) Do fish have forelimbs? Explain why or why not. 12) What can be said about the genomes of animals that have homologous structures?

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Station 5

Natural Selection Changes Populations Over Time Introduction Evolution is the process by which living things change over many generations. Evolution requires only three simple things in order to occur. First, individuals of a species must have variation, which means they are different from one another. Second, these differences must be heritable (inherited by offspring from their parents). Third, some of these differences must make certain individuals more likely than others to survive and reproduce (the ability to survive well enough to reproduce is called fitness). When individuals with greater fitness have more offspring than those with lower fitness, natural selection has occurred. That’s it! As long as there are heritable differences among individuals, and these differences make some individuals more successful at survival and reproduction than others, evolution by natural selection will occur. At this station, you will observe how differences in reproductive success cause populations to become different over time.

Procedure • Decide what kind of organism you are going to be as a class. e.g. “We are birds.” • Split into two equal teams. With your team, choose an adaptation you will have that will improve your fitness over the other team in some environment. e.g. “Team A can fly longer distances to find food,” and “Team B has a stronger beak to crack hard nuts.” Identify your teams with two different colored chips, blocks, cards, etc., ~50 per team. • Flip a coin. Heads means the environment favors Team A. Tails favors Team B. • After every coin toss, the winning team puts 3 chips into a box. The losing team puts only one chip into the box. This represents the next generation. • Empty the box and count. Write down how many individuals from your team made it into the next generation. Flip the coin again. For each individual who made it into the next generation, put either 1 or 3 chips into the box. • What is the proportion of colors in the box after this generation? Repeat the coin toss. • ADDITIONAL STEP: At the teacher’s discretion, the environment can stay steady through multiple turns (favoring one team over the other). • ADDITIONAL STEP: At the teacher’s discretion, a natural disaster can remove half of the chips in the box at random. • ADDITIONAL STEP: At the teacher’s discretion, the “carrying capacity of the environment”, that is the total number of chips in the box, can be set. Once the population grows to that size, the team that wins the toss gets to replace 1/3 of the losing team’s chips with their own chips, keeping the total number the same. Does a team go extinct?

Analysis Questions

1) 2) 3) 4) 5)

 How does this proportion of colors change in every generation? H  ow did the proportion change when the environment consistently favored one team over the other? How did the random disaster change the proportion? How was the game different when the “carrying capacity” of the environment was set? How does this game help you to understand the process of evolution?

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