Question

In the absence of suitable fossil representatives to calibrate nodes within a molecular phylogenetic tree

(i.e. based on DNA sequences), what calculations/assumptions can be used to estimate the amount of

‘evolutionary time’ that has passed along any particular branch of the tree?

Answer 1

DNA dating is one of the method by which we compare the ancestral genome and the present day genome.By looking at the mutational rates we can get a phylogenetic tree.The changes in the genome will be inherited through generation by the gametes.And as the generation passes more and more mutations will be there.Knowing the rate of these changes we can calculate the time needed to accumulate that many differences.This tells us how long it's been individuals shared the ancestors.