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Explanation for deviation from Hardy-Weinberg Equilibrium

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1. Why do gene frequencies in a population change? Why don't they stay the same from one generation to the next? Explain how the processes of mutation, crossover, and natural selection can provide an answer to these questions.

Support your response with cited documentation where appropriate.

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Consider the example of Hardy-Weinberg equilibrium provided as an attachment.

The population has a slight deviation from Hardy-Weinberg equilibrium in the above case as p2+2pq+q2=0.98 instead of 1.0.This situation of disequilibria might be the result of small population size, migration and selective forces which favor or hinder the expression of certain phenotypes. It can also occur due to non-random mating. Here, the slight variation might also be due to polygenic effects of genes, wherein different loci additionally affect a particular trait. At times, it may be due to the existence of lethal alleles present in a population, as a result of which, most recessive alleles, be it lethal or not, are not expressed in every generation; instead, they will be ...

Solution Summary

The situation of disequilibria or deviation from Hardy-Weinberg equilibrium might be the result of small population size, migration and selective forces which favor or hinder the expression of certain phenotypes. It can also occur due to non-random mating.

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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).

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