Maternal Ancestors and Mitochondrial Sequences

Questions

1. These sequences were obtained from people throughout the world.
  • Were you able to confirm the source any (or all) of the "known" sequences?
    e.g. did the sequence marked "Italy" come from someone native to Italy?

  • Were you able to identify the source of any of the unknown sequences?

  • Sometimes it happens that the test mitochondrial sequences are 100% identical to sequences from individuals who live in different countries. In this case, first, remove the low complexity filter and repeat the search. If you get the same result, refer to a map to see where the countries are located relative to each other. Can you come up with an explanation for your result?

2. Use data from your blastn search to support your conclusion about the origin of your sequences (known and unknown). Compare the data from the best matching sequence with the second best and worst matches in the blastn results.

Examples of these data include the:

  • % identity,
  • number of mismatched bases,
  • e value,
  • the length of the alignment

3. Repeat the blastn search, but this time exclude sequences from the region of your closest match. For example, "russia" was excluded in the demonstration because the sequence was found to originate in Siberia. If you have two countries, like Russia and China, that match to the same extent, you can exclude both by using the Entrez query: mito* NOT russia NOT china.

  • Which region matches most closely now?

    •
  • How many different regions are represented in your alignment list?

    •
  • What do these results suggest about human migration?

 

A longer term project

Researchers have used these types of experiments to chart the migration of humans out of Africa and answer questions about human origins. One of the question that has been addressed by this type of study has been the origin of the Polynesians. A Norwegian researcher named Thor Heyerdahl proposed that the Polynesians traveled to the islands from South America. He tried to determine if this was possible by testing the ability of small boats to traverse the Pacific. See if you can answer this question, using mitochondrial DNA.



Copyright Geospiza, Inc.

    

    
Funding for this project was provided by the National Science Foundation's Course, Curriculum, and Laboratory Improvement Program under grants DUE-0088153 and DUE-0127599

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