ratebytree | R Documentation |
Multiple methods for comparing the rate or process of evolution between trees.
ratebytree(trees, x, ...)
## S3 method for class 'ratebytree'
posthoc(x, ...)
trees |
an object of class |
x |
a list of trait vectors for a continuous trait in which the names of each vectors correspond to the tip labels of |
... |
optional arguments, including the argument |
This function essentially implements three different methods for comparing the rate or process of evolution between trees: one for continuously-valued traits, a second for discrete characters, and a third for the rate of diversification (speciation & extinction).
In all cases, the function takes an object of class "multiPhylo"
containing two or more phylogenies (trees
), and (for the first two analyses) a list of trait vectors (x
).
For continuous traits, the function then proceeds to fit two models: one in which the rate (or regime, for models "OU"
and "EB"
) of trait evolution is equal among all trees; and a second in which the rates or regimes can differ between trees.
The latter model corresponds to an extension of the censored approach of O'Meara et al. (2006; Revell et al. 2018) and should also be related to the method of Adams (2012) for comparing rates among traits. See brownie.lite
for a different implementation of the noncensored approach of O'Meara et al. (2006).
For discrete traits, the function instead proceeds to fit two variants of the Mk model (Lewis 2001): one in which the parameters values (transition rates) of the process are free to vary between trees, and a second in which they are fixed to be the same.
For diversification alone, the function fits two different diversification (speciation & extinction) models (Nee et al. 1994; Stadler 2012): one in which the birth (speciation) and death (extinction) rates are identical between the trees, and a second in which they are permitted to differ in various ways depending on the value of "model"
(Revell 2018).
The method posthoc
conducts a post-hoc comparison of parameter estimates between trees in the multi-rate or multi-process model. The parameter that is compared depends on the fitted model. For instance, in model="BM"
posthoc comparison is made of sig2
; if model="OU"
fitted values of alpha
are compared; and so on. The argument p.adjust.method
can be used to specify a method for adjusting P-values for multiple tests following p.adjust
(defaults to p.adjust.method="none"
.
At present it is not possible to specify different models to fit for the different trees - although if (for instance) character evolution on tree 1 proceeded by a strong OU process while character evolution on tree 2 was by BM, we would probably reject a constant-process model and tree 2 should show a very low value of alpha
.
To compute the standard errors for each fitted parameter value, the function computes the negative inverse of the Hessian matrix at the MLEs; however, if this matrix is computationally singular the generalized inverse (ginv
) will be used instead without warning.
The function also conducts a likelihood-ratio test to compare the two models.
For continuous character, optional arguments presently include the following: model
, the model of continuous trait evolution (options are "BM"
, the default, "OU"
, and "EB"
). tol
, used as a minimum value for the fitting rates, to prevent problems in optimization. trace
, a logical value indicating whether or not to report progress in the optimization. test
, the method for hypothesis testing (options are "chisq"
and "simulation"
). quiet
, a logical value indicating whether or not to run perfectly quietly. Finally, se
, a list of vectors containing the standard errors for each value of x
.
For type="discrete"
the optional arguments are slightly different. The argument model
can be used, but it must assume the values "ER"
, "SYM"
, "ARD"
, or a numeric matrix following ace
.
Finally, for type= "diversification"
models are so far "birth-death"
, "equal-extinction"
, and "equal-specation"
, and "Yule"
. It is also important to consider supplying the sampling fractions, rho
, which is a vector of values between 0 and 1 of the same length as trees
. If not provided the method will assume a sampling fraction of 1.0 for all trees - which is seldom true of empirical studies.
An object of class "ratebytree"
or an object of class "posthoc.ratebytree"
in the case of the method posthoc
.
Liam Revell liam.revell@umb.edu
Adams, D. C. (2012) Comparing evolutionary rates for different phenotypic traits on a phylogeny using likelihood. Syst. Biol., 62, 181-192.
Lewis, P. O. (2001) A likelihood approach to estimating phylogeny from discrete morphological character data. Systematic Biology, 50, 913-925.
Nee, S., May, R. M. and Harvey, P. H. (1994) The reconstructed evolutionary process. Philosophical Transactions of the Royal Society of London B, 344, 305-311.
O'Meara, B. C., C. Ane, M. J. Sanderson, and P. C. Wainwright. (2006) Testing for different rates of continuous trait evolution using likelihood. Evolution, 60, 922-933.
Revell, L. J. (2018) Comparing the rates of speciation and extinction between phylogenetic trees. Ecology and Evolution, 8, 5303-5312.
Revell, L. J. (2024) phytools 2.0: an updated R ecosystem for phylogenetic comparative methods (and other things). PeerJ, 12, e16505.
Revell, L. J., Gonzalez-Valenzuela, L. E., Alfonso, A., Castellanos-Garcia, L. A., Guarnizo, C. E., and Crawford, A. J. (2018) Comparing evolutionary rates between trees, clades, & traits. Methods Ecol. Evol., 9, 994-1005.
Stadler, T. (2012) How can we improve the accuracy of macroevolutionary rate estimates? Systematic Biology, 62, 321-329.
brownie.lite
, fitMk
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