Part 4 - Introduction

| The Diversity of Life

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To benefit from this simulation, you should be able to:
• Identify and define the following terms: allele, phenotype, genotype, natural selection, homozygous, and heterozygous.
• Describe the Hardy-Weinberg principle.
• List the conditions under which the Hardy-Weinberg principle holds.
• Calculate values to determine if a Hardy-Weinberg equilibrium exists.

After completing this simulation, you will be able to:
• Recognize Hardy-Weinberg equilibrium.
• Describe how natural selection impacts evolution.
• Discuss the relationship between changes in allele frequencies and evolution.
• Discuss genotypic frequencies.

How does natural selection cause evolution?

Desert Island
Imagine that you are a scientist who studies evolution. You have just discovered an isolated tropical island surrounded by the Pacific Ocean. You observe that the island has fruit trees producing a dark-skinned fruit attractive to a particular species of fly. The flies feed and reproduce on the fruit. The population of flies is very large, and there appear to be no fly predators on this island. The fruit tree produces fruit continuously throughout the year. You observe that the flies on the fruit come in one of two colors, light tan and black. There appear to be approximately as many black flies as there are tan flies. The color of the flies appears to have no influence on mate selection, viability, or overall fitness. As a scientist, it occurs to you that this island provides an ideal opportunity to test the Hardy-Weinberg principle and the hypothesis that natural selection can produce challenges in allele frequencies. You are aware that by measuring changes in allele frequencies you are measuring evolution.