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    Evolution of reproductive behavior in Western Butterfly.

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    Details: According to the Theory of Evolution, Natural Selection is the mechanism by which evolution occurs. Remember: evolution occurs at the level of the population. Individuals do not evolve, populations evolve.
    The process of Natural selection is based on the following four postulates:

    Postulate 1 - Individual members of a population differ from one another in many respects.

    Postulate 2 - At least some of the differences among members of a population are due to characteristics that may be passed from parent to offspring. That is, they are heritable or genetic.

    Postulate 3 - In each generation, some individuals in a population survive and reproduce successfully but others do not.

    Postulate 4 - The fate of individuals is not determined by luck. Instead, an individual's likelihood of survival and reproduction depends on its characteristics. Individuals with advantageous traits survive longest and leave the most offspring, a process known as Natural Selection.

    Choose ONE animal species. Describe the way in which an evolutionary change might occur for a particular characteristic (trait) of that species as a result of natural selection. The characteristic could be something like coloration pattern, length of the limbs, or size of the teeth or beak, or any measurable trait that is inherited.
    The organism you choose should be a real one but the evolutionary change you describe can be real or theoretical.

    In your own words,
    a. Explain how the change in this trait occurs in terms of the four postulates listed above and in the book. You will describe what the population starts out like at time zero and then what it will look like at a later time, as a result of natural selection.

    b. Explain the process by which the changes occurred. What is the selective pressure? Explain why the change might confer more fitness to a particular environment?

    Tips: Make sure to include the following in your answers to a and b above:
    Clearly state the name of the SPECIES you are going to be talking about for this assignment. (Make sure you know what is meant by a species.)
    Also, clearly state what population of the species you are going to talk about by specifying its geographic location. (Make sure you understand what a "population" is.)
    Clearly state the characteristic (trait) of the population that you are going to be talking about and explain how this trait varies among individuals.

    Explain what change occurs in the environment that causes a change in the above characteristic (trait)?

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    Solution Preview

    Evolution of reproductive behavior in a Western butterfly, Edith's checkerspot (Edith editha):

    The rapid evolutionary adaptation in a population of a butterfly species known as Edith's checkerspot (Edith editha) which lives in a meadow near Carson city of Nevada has been studied by Michael Singer and Camille Parmesan of the University of Texas. The females of the species lay eggs on plants which provide food for their larvae to hatch. Usually the females used to deposit their eggs on a plant native to the region known as Collinsia torreyi. They used the tasting cells present on their feet in order to identify the plant. For instance, during 1983, checkerspots laid almost 80% of their eggs on Collinsia.

    But during the next decade, a weed known as Plantago lanceolata invaded the meadow from the cattle ranches surrounding the region. Thus, by 1993, within a span of 10 years, the butterflies began to lay almost 70% of their eggs on the plant that invaded the ...

    Solution Summary

    The solution explains the change in a trait related to reproductive behavior that occurs among the population of Western Butterfly as a result of natural selection. It also provides indepth information regarding the process by which the change occured. It explains the meaning of selective pressure along with how the change confers more fitness of the population to a particular environment.