Question 3 4 points Use the hypothetical phylogeny and seque

Question 3

(4 points)

Use the

hypothetical phylogeny and

sequence data

given below to es

timate the divergence time between Species 2

and Species 3. Briefly explain your method

Fossil 15 My old Estimated divergence time CTT ACT GGT CGA TCT Species 1 CTA ACT GGT CGG TCA. Species 2 CTA ACA GGC CGG TCA Species 3

Solution

According to the molecular clock assumption, the number of nucleotide substitution in the related genes of two species is directly proportional to the divergence time i.e. the time they shared the last common ancestor. In the given nucleotide sequence, species 2 and species 3 differ from each other in two nucleotides; at position 6 and position 9. So, the divergence time is 2my.