Question

multiple choice question
building phylogenetic trees using the distance - based approach entails ______.

• an assumption that the fewest number of changes occurred between living and ancestral organisms
• calculating the percent differences in pairwise comparisons of aligned sequences
• calculating the probability that a particular tree can be constructed, based upon a particular evolutionary model

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Explanation:

• The first option describes the parsimony approach, not distance-based phylogenetics.
• The third option refers to the maximum likelihood (model-based) method for phylogenetic tree building.
• Distance-based methods rely on measuring genetic distance, typically via percent differences in aligned sequence pairs, then clustering organisms based on these distances.

Answer:

calculating the percent differences in pairwise comparisons of aligned sequences