Below are shown segments of DNA from three species of flies.Species 1 is the common ancestor of species 2 and species 3, and we have access to its DNA because it was preserved in amber.
Species 1: AACTACTGCACGCTCATA
Species 2: AACTAGTGCTCGCTCACA
Species 3: AATTACTGCACGCTCACA
There have been _______ single and _______ parallel changes as species 2 and 3 evolved from species 1.

Question

Below are shown segments of DNA from three species of flies.Species 1 is the common ancestor of species 2 and species 3, and we have access to its DNA because it was preserved in amber. 
Species 1: AACTACTGCACGCTCATA
Species 2: AACTAGTGCTCGCTCACA
Species 3: AATTACTGCACGCTCACA
There have been _______ single and _______ parallel changes as species 2 and 3 evolved from species 1.

Quizplus · Accepted Answer

To determine the number of single and parallel changes, we compare the DNA sequences of the species. Species 1: AACTACTGCACGCTCATA Species 2: AACTAGTGCTCGCTCACA Species 3: AATTACTGCACGCTCACA Single changes: 1. T to G in species 2 (position 6) 2. C to A in species 2 (position 17) 3. A to T in species 3 (position 4) These are changes that occurred uniquely in species 2 or 3. Parallel change: 1. T to A in the last position (18) for both species 2 and 3. This is a change that occurred in the same position in both species, indicating a parallel evolution from the common ancestor. Therefore, there are three single changes and one parallel change.

Below Are Shown Segments of DNA from Three Species of Flies.Species