Forces of Evolution Recap: Natural Selection: The process by which biological variation (adaptations) becomes more comm

Forces of Evolution

Recap:

Natural Selection: The process by which biological variation (adaptations) becomes more common in a population over generations.

Mutation: Chemical change in the DNA. It can be positive, neutral, or deleterious (causing harm or damage).

Gene Flow: Transfer of genes across population boundaries because their members are breeding with one another.

Genetic Drift: When random factors cause a change in allele frequency over time. These factors have nothing to do with genetic health or an organisms fitness for its environment.

1. Skin Color Around the World  

Around the world, populations near to the equator and in areas of high altitude have darker skin (their skin produces more melanin). Populations at northern latitudes have lighter skin- their skin produces less melanin. 

What forces of evolution are at work? Check all that apply. 

    ___ Mutation 

    ___ Natural Selection 

    ___ Genetic Drift

    ___ Gene Flow 

Specifically, how is natural selection involved? 

Explain how the forces of evolution shift allele frequencies in the population over time. Your answer should include all of the forces of evolution that you identified as being used (above). Write a paragraph or more explaining how new traits are introduced, how individuals are selected (if present), and how alleles in the population shift over time. 

2. Founding the Colony of Zygozia 

Lets pretend that there is a community called Zygozia. They say that they founded their small island colony in the South Pacific in 1959. When they arrived, there were no people living on the island, and so they became the only inhabitants. They came from the west, most likely Southeast Asia. The Zygozians of 2018 are unusual in that 80% of them have a rare genetic condition. Populations from Southeast Asia, whom the Zygozians descended from, only show this condition in 3% of their population. What happened? 

What forces of evolution are at work? Check all that apply. 

    ___ Mutation 

    ___ Natural Selection 

    ___ Genetic Drift

    ___ Gene Flow 

Specifically, how is natural selection involved? 

Explain how the forces of evolution shift allele frequencies in the population over time. Your answer should include all of the forces of evolution that you identified as being used (above). Write a paragraph or more explaining how new traits are introduced, how individuals are selected (if present), and how alleles in the population shift over time. 

3. Native Americans and Type O Blood 

Modern Native Americans have very high frequencies of Type O blood. In some places in North and South America, the frequency is as high as 100%. Anthropologists believe that early Native Americans arrived in North America by crossing over the Bering Land Bridge around 15,000 years ago, from East Asia. Modern East Asian populations, with whom modern Native Americans share ancestry, do not have high frequencies of Type O blood. Instead, they have some of the lowest frequencies of Type O blood in the world. 

What forces of evolution are at work? Check all that apply. 

    ___ Mutation 

    ___ Natural Selection 

    ___ Genetic Drift

    ___ Gene Flow 

Specifically, how is natural selection involved? 

Explain how the forces of evolution shift allele frequencies in the population over time. Your answer should include all of the forces of evolution that you identified as being used (above). Write a paragraph or more explaining how new traits are introduced, how individuals are selected (if present), and how alleles in the population shift over time. 

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