perished. By chance, one or several fertilized female flies could have landed on the more recently formed island of Oahu. Also by chance, some of the descendants of these fertilized females eventually acquired several other chromosomal inversions, the ones labeled p, q, s, and d in Table 1. Over many generations these inversions became more common until all of the members of the Oahu population of flies carried them….

The narrative should address these points:

  1. What are the different ways in which the flies could have spread from island to island?

  2. Of the 11 inversions shown in the table, which are likely to be older and which younger, both for the four species examined and for all 13 of the species in the table?

  3. Do new species tend to form on younger islands?

After the narrative or narratives have been written and shared, the following questions could help guide a class discussion:

  1. Which aspects of the narrative are supported by the limited set of data available?

  2. Which aspects of the narrative are not supported by the data?

  3. What additional data can be collected and analyzed to modify, verify, or augment the narrative?

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