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*log-likelihood),
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) ## 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). |
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 will be detailed in a forthcoming paper.
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.
DNAmodel
, nj
, read.dna
,
summary.phylo