Suppose three sibling species of frogs have the following DNA sequences at a portion of a gene:
Species 1: AGTCTAGATCGCGGTCG
Species 2: AGTCGATCGCGGACG
Species 3: TGTCTAGATCACGGTCG

Recall that the observed number of mutations can differ from the total number of actual substitutions that occurred in pairwise sequence comparisons.If we assume that a gap of any length is equivalent to three nucleotide substitutions, how many substitutions have occurred between Species 1 and Species 2?

Question

Suppose three sibling species of frogs have the following DNA sequences at a portion of a gene: 
Species 1: AGTCTAGATCGCGGTCG
Species 2: AGTCGATCGCGGACG
Species 3: TGTCTAGATCACGGTCG

Recall that the observed number of mutations can differ from the total number of actual substitutions that occurred in pairwise sequence comparisons.If we assume that a gap of any length is equivalent to three nucleotide substitutions, how many substitutions have occurred between Species 1 and Species 2?

Quizplus · Accepted Answer

Species 1: AGTCTAGATCGCGGTCGSpecies 2: AGTCGATCGCGGACGComparing the sequences of Species 1 and Species 2, we find:1. A deletion (or gap) in Species 2 (missing "T" after the first "AGTC"), equivalent to three substitutions.2. A substitution of "A" to "G" in the second to last position.Therefore, the total number of substitutions is 3 (for the gap) + 1 (for the A to G substitution) = 4.

Suppose Three Sibling Species of Frogs Have the Following DNA