brief introductions

dating.ipynb contains following key steps for evaluating the essential differences within a MCMCtree dating analysis

1. Branch length estimated by the baseml/codeml. It could be used to check if there are paralogs within input alignment and check the feasibility of the genes.
   1. If the value larger than 4 (empirical value), it should be careful check or dropped
2. Posterior rates estimated by the MCMCTREE. It should be similar with the posterior time estimates. But you could use it to check if there are any rate differences between lineages.