mlphylo {ape} | R Documentation |
mlphylo
estimates a phylogenetic tree by maximum likelihood
given a set of DNA sequences. The model of evolution is specified with
the function DNAmodel
.
logLik
, deviance
, and AIC
are generic functions
used to extract the log-likelihood, the deviance (-2*logLik), or the
Akaike information criterion of a tree. If no such values are
available, NULL
is returned.
mlphylo(model = DNAmodel(), x, phy, search.tree = FALSE, quiet = FALSE) ## S3 method for class 'phylo': logLik(object, ...) ## S3 method for class 'phylo': deviance(object, ...) ## S3 method for class 'phylo': AIC(object, ..., k = 2)
model |
an object of class "DNAmodel" giving the model to
be fitted. |
x |
a matrix, a data frame, or a list giving the (aligned) DNA sequence data. |
phy |
an object of class "phylo" giving the (initial)
tree. |
search.tree |
a logical specifying whether to search for the best tree (defaults to FALSE) (not functional for the moment). |
quiet |
a logical specifying whether to display the progress of the analysis. |
object |
an object of class "phylo" . |
k |
a numeric value giving the penalty per estimated parameter;
the default is k = 2 which is the classical Akaike
information criterion. |
... |
further arguments passed to or from other methods. |
The present version is a pre-alpha release. All comments, suggestions, bug reports, are warmly welcome.
The model specified by DNAmodel
is fitted using the
standard ``pruning'' algorithm of Felsenstein (1981). An algorithm for
the estimation of tree topology is under development, and will be
released when ready.
The implementation of the inter-sites variation in substitution rates follows the methodology developed by Yang (1994).
The difference among partitions is parametrized with a contrast parameter (denoted xi) that specifies the contrast in mean susbtitution rate among the partitions. This methodology is inspired from one introduced by Yang (1996).
The substitution rates are indexed column-wise in the rate matrix: the first rate is set to one.
an object of class "phylo"
with branch lengths as estimated by
the function. There are two additional attributes:
loglik |
the maximum log-likelihood. |
para |
the estimated parameters for each partition. |
For the moment, it is not possible to estimate neither branch lengths,
nor the topology with mlphylo
: this is still in development and
will be released when ready. The function may estimate all other
parameters: substitution rates, shape (alpha) of the
inter-sites variation in substitution rates, the proportion of
invariants, and the ``contrast'' parameter (xi) among
partitions.
Alternative topologies can also be compared using likelihood-ratio tests (LRTs) or AICs.
Emmanuel Paradis paradis@isem.univ-montp2.fr
Felsenstein, J. (1981) Evolutionary trees from DNA sequences: a maximum likelihood approach. Journal of Molecular Evolution, 17, 368–376.
Yang, Z. (1994) Maximum likelihood phylogenetic estimation from DNA sequences with variable rates over sites: approximate methods. Journal of Molecular Evolution, 39, 306–314.
Yang, Z. (1996) Maximum-likelihood models for combined analyses of multiple sequence data. Journal of Molecular Evolution, 42, 587–596.
DNAmodel
, nj
, read.dna
,
summary.phylo