Question

What is a molecular clock? How is it used to calculate divergence times, and what are the assumptions of this type of analysis?

Answer 1

Molecular clock is a specific tool used by scientists to estimate the divergence time between two species sharing a common ancestor.

It relies on the fact that DNA sequences diverge with time and assumes that mutation rate are more or less constant.

It is assumed that mutations (substitutions) with respect to specific genes within the two species under consideration, is proportional to the divergence time from the common ancestor. That is, it is equivalent to the time period that passed since the two genes separated from each other.