Study the table below.
Organism Pair Percentage of DNA Similarity
A – B 97
A – C 85
A – D 50
a. To which organism, B, C or D, is organism A most closely related? Support your answer.
b. Which pair of organisms in the table is least closely related? Support your answer.
c. Which pair of organisms most likely shares a recent common ancestor? Support your answer.
a. A because they have the greatest percentage of similarity in their DNA, which means that their last common ancestor was the most recent.
b. a and d are the least closely related because they share the least percentage of similar DNA , their common ancestor was the farthest in the past so they have had more time to evolve in different directions to fulfill their niches.
c. a and b because they have the most similar DNA which means they have had the least time to evolve away from each other, to specialize for their niches.