Molecular phylogeny

Molecular phylogeny is phylogeny involving the comparison of genes. The genes used must be chosen carefully: they need to be genes which have high functional requirements placed on them, which therefore have a low mutation rate.

A good example is cytochrome B which is involved in the cellular oxidation systems in all living beings (modern living beings have undoubtedly inherited it from a common ancestor some three billion years ago).

Mutations, however, accumulate over time and to account for this affect Zuckerland and Pauling (1962) developed the theory of the molecular clock.