Question

Part 3. Suppose we are sure, because of numerous characters, that species 1, 2, and 3 are more closely related to one another than to species 4 (an outgroup). We sequence a gene and find ten nucleotide sites that differ among the four speciesThe nucleotides at these sites are Species 1! G C T G A T G A GT Species 2! AT CA AT G A G T Species 3! G T T G CAAC GT Species 4 (outgroup)!G T CA AT G A CA A. Determine the evolutionary transitions required for each of the three possible phylogenies for species 1, 2, and 3. Indicate the minimum number of transitions required for each tree. Tree A Species 4 Species 1 Number of required transitions OneN Species 2 Species 3 Species 4 Tree B Species 2 Number of required transitions Species 1 Species 3 Species 4 Tree C Species 3 Number of required transitions Species 2 Species 1 B. Which tree is the most parsimonious?

We didn't spend much time on this in lecture and I can't get it. Thanks in advance!

Answer 1

TREE A-

for converting species 4 into species 1 we need 5 transition (base change).

for converting species 1 into species 2 we need 4 transition (base change).

for converting species 2 into species 3 we need 7 transition (base change).

total transition needed = 16.

TREE B -

for converting species 4 into species 2 we need 3 transition (base change).

for converting species 2 into species 1 we need 4 transition (base change).

for converting species 1 into species 3 we need 5 transition (base change).

total transition needed = 12.

TREE C -

for converting species 4 into species 3 we need 8 transition (base change).

for converting species 3 into species 2 we need 7 transition (base change).

for converting species 2 into species 1 we need 4 transition (base change).

total transition needed = 19.

tree b is most parsimonious