John P. Huelsenbeck and Sebastian Höhna (UC Berkeley and Stockholm University)
connect to Phyloseminar.org
RevBayes is a computer program that uses directed acyclic graphs
(DAG's) to specify any type of model, to hold the model and data in
memory, and to compute the likelihood of the parameters of the model.
DAG's provide a framework for the construction of modular models.
Models can easily be extended and/or parts of the model exchanged
(e.g., the substitution process and clock model) and several models
can be combined. The design of RevBayes should allow the
implementation of any extension to existing models. RevBayes is mainly
developed for Bayesian phylogenetic analyses, but it can be extended
to any inference on probabilistic models.
In this talk, I will give a brief introduction to the concept of DAG's
and how they are used to construct a model. Once the model is
specified, I will show how to simulate new observations under the
model and how to estimate its parameters. I will demonstrate this in
the RevLanguage, which is an R-like language for building DAG's for
phylogenetic problems. The RevLanguage is used interactively to
specify the model, as done with R. I will show how a full phylogenetic
model is specified, step-by-step. I will mainly focus on various
standard substitution models, relaxed clock models, and divergence
times priors. Specifically, I will show a new birth-death model with
speciation and extinction rates varying over time and use this in a
integrative analysis. In the integrative analysis I condition only on
the alignment (only the alignment is considered to be known) and
estimate the tree and divergence times simultaneously as well as the
speciation and extinction rates.