BARCE settings


Model options

Model (JC+gaps, K2P+gaps, F81+gaps and F84+gaps) M F84
Estimate initial character frequencies from data E YES
Estimate transition/transversion ratio from data R YES
Frequencies of the three topologies P 0.333333 0.333333 0.333333
Difficulty of changing trees D 0.9
Read in initial hidden state sequence? J YES

This uses the F84 (Felsenstein 84) model of nucleotide substitution, estimates both the initial stationary frequencies and the transition-transversion ratio from the data, sets the initial recombination parameter lambda to 0.9, selects a uniform a priori distribution on the tree topologies, and reads in the initial state sequence from mosaic.in.


Run settings menu

Length of the burn-in period B 1000000
Length of the sampling period . 1000000
Number of points to return N 1000
Thinning interval I 1000
Tuning interval (for proposal distributions) C 100
Update lambda with Gibbs sampling W YES
Annealing scheme for lambda Q PAR
Update stationary frequencies in MCMC algorithm U YES
Update transition-transversion ratio in MCMC algorithm A YES
Branch length in initial trees O 0.1

This uses an equilibration (or burn-in) period of 1,000,000 MCMC steps, after which 1000 configurations are sampled in intervals of 1000 MCMC steps, amounting to 1,000,000 MCMC steps altogether. These values are over-cautious and can possibly be considerably reduced. During equilibration, the parameters of the proposal distribution are adjusted in intervals of 100 MCMC steps. We sample the transition-transversion ratio, the nucleotide stationary frequencies and the recombination parameter lambda from the posterior distribution, and apply the PAR version of simulated annealing. The initial branch length should be set to the average value of the global maximum likelihood tree, 0.1 in this case. For further information on the parameters, click here.


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