Relaxed phylogenetics and dating with
Distributions assigned to parameters before the analysis of the data.
going from fast to slow or slow to fast suddenly, rather than needing to steadily increase or decrease over multiple adjoining branches. Apart from a strict molecular clock, a variety of models for relaxing the molecular clock assumption have been developed and implemented in BEAST. These are accessible in the ‘Clocks’ panel in BEAUti: A strict clock model assumes that every branch in a phylogenetic tree evolves according to the same evolutionary rate. With recent advances in Bayesian clock dating methodology and the explosive accumulation of genetic sequence data, molecular clock dating has found widespread applications, from tracking virus pandemics and studying the macroevolutionary process of speciation and extinction to estimating a timescale for life on Earth. Used the idea of approximate rate constancy to calculate the age of the alpha and beta globin duplication event. Chapter 4 has an extensive discussion of morphological versus molecular rates of evolution.. In Bayesian clock dating, the prior on divergence times is specified using a branching model, possibly incorporating fossil calibration information, and the prior on evolutionary rates is specified using a model of rate drift (a relaxed-clock model).