biology

Topics: Natural selection, Mutation, Evolution Pages: 3 (947 words) Published: February 2, 2014

Experiment 8.1
Yes there was a change because with the starting snail population there was a great variation from 1-7. After the crab began eating only the snails with the thickest shells survived. The snails with the thinnest shells were eaten by the crab. Only snails with shell thickness 4-7 were left after the crab had their meal. The original snails with thickness 1-3 were eliminated from the population by the crab. The crab will usually try to expend as little enrgy as it can to maximaize its happiness so the snails with thinner shells will likely be targeted first and eventually eliminated. 17.1

When predatory crabs are present in the snail population thinner shells were eaten much faster than when I was predator. The offspring that resulted only had thicker shells with predatory crabs but with me there were still crabs with thin shells. One reason is that there were four predatory crabs as opposed to just 1 which was me. Four crabs eat a lot more and much faster than me. Furthermore, since there are more crabs they would eat whatever crab came their way whether thick or thin while I was more picky and went for thinner shells. Exercise 2

6.1
There was no change. Even though predators were eating just as much snails, with natural selection if overtime snails stay constant, it means that its well adapted to its environment. If there is no variation in the population, there is no way to obtain new traits. The reason we get different shell thickness is because there are different variation existing in the population. If you start with shells that are only thick, then you cant get variation in population unless there is random mutation. If all snails have thickness then the offspring will have same thickness unless there is random mutation. 13.1

They are similar because the mating was random; however, there is selection for thicker shell crabs which mostly eat thinner shells. Thicker ones got to live and pass off traits to their offspring. Thin...
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