1. How might the flies have traveled from one island to another?

  2. How might new species of flies have evolved on the islands where they now live?

  3. In what order did the inversions shown in the table occur?

  4. Which species might be older and which might be younger?


In the elaboration phase of the investigation, additional data from Table 1 or the data from Table 2 can be analyzed. Using all the data in Table 1 permits the construction of a much larger phylogenetic tree showing the evolutionary relationships among the 13 species of flies described in the table. The data in Table 2 permit the construction of a second tree that reveals an even more complex set of evolutionary relationships among the 18 species of picture-winged flies represented in the two tables.

Questions to consider in light of these additional data include the following:

  1. Are the chromosomal inversion data always sufficient to distinguish species?

  2. Does the presence of an inversion necessarily mean that one species is younger than another?

  3. Can a relatively young species occur on an older island?

  4. What are the mechanisms that would enable this to occur?

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