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SLP Natural Selection and Ecology

For each of the SLP assignments, you will be provided with a hypothetical experimental scenario or data. These assignments are more opened-ended than the case assignments. You will speculate about possible explanations and the ways they might be tested, but be sure to that your hypotheses are grounded in accepted biological science. In doing this, you will mimic the action of scientists who are continuously collecting new data, formulating hypotheses, and testing their ideas.

You are part of a team of scientists exploring a small, newly discovered island. This island is located approximately 150 miles off the coast of the mainland. Preliminary evidence suggests that humans have never populated the area and have likely had almost no presence on the island. In your work cataloging the various organisms on the island, you have discovered a new population of birds. Their gross appearance is very similar to a known species on the mainland. Genetic data also suggest that there is a close relationship between the new population and the species on the mainland. However, the coloration pattern of the newly discovered birds is distinct. The mainland birds are primarily brown with splotches of red on the back and wings. The individuals in the new population of birds are largely red with patches of deep purple on the wings and small crests on the top of their heads. Such crests and patches of purple are known to exist in the mainland species but are rare.

Speculate on possible explanations of these observations. Hypothesize on the past events that may have led to this phenomenon and also link your explanation to the underlying molecular basis of inheritance.

Assignment Expectations:

For this SLP, use your understanding of the mechanism of evolution. Consider the various circumstances that might have allowed this situation to develop. Fully explain your hypothesis and the evidence that supports it. When suggesting known evolutionary phenomenon be sure to explain them (i.e., don't simply state "convergent evolution", but rather explain what that means and why it applies to this situation).

Solution Preview

Title: Speciation

Introduction

Evolution is defined when the relative frequencies of alleles in a population change over successive generations. (1) The causes of evolution are natural principles that act against the Hardy-Weinberg equilibrium, which states there should be no natural selection in a population. (1) However, there are five potential agents of evolution that can make the population evolve; the five are genetic drift, gene flow, mutation, non-random mating, and natural selection. (1) One of the causes of microevolution that can lead to favorable adaptation to the environment is natural selection. (1) Natural selection have an impact on the frequency of a heritable trait in a population in three different ways: stabilizing selection that discriminates against extreme phenotypes; directional selection, which favors relatively rare individuals on one end of the phenotypic range; and diversifying selection that favors individuals at both extremes of a range over intermediate phenotypes. (1) In the case of the new population of birds on the new island that differ from birds in the mainland, these is an example of natural selection or directional selection because members of the birds from the mainland probably migrated or lost to a new habitat with different environmental conditions. (1) The birds that inhabited the new island have adapted to the environmental conditions of that island giving them different phenotypic traits. (1) Directional selection favors the rare individuals on the new island that deviate from the average traits of birds on the mainland. (1) Analogous to Darwin finches in the Galapagos Islands that were also distinct compared to finches in South America, the birds had probably been blown by a storm or separated to each of the islands from one island or from the mainland. (1) As a result of ...

Solution Summary

SLP natural selection and ecology are examined.

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