ratebystate: Method for investigating the rate of one trait as a function of the state of another
Description
This function attempts to ask if the rate of a continuous character, y
, depends on the state of a separate continuous trait, x
. This is accomplished by regressing the squared contrasts in y
on the branch or node ancestral estimates of x
.
Usage
ratebystate(tree, x, y, nsim=100, corr=c("pearson","spearman"), ...)
Arguments
x
a continuous character - the dependent variable in the model.
y
a second continuous trait - the response variable.
nsim
number of simulations for hypothesis testing.
corr
correlation method to use. Same as in cor
. ...
optional arguments which include sim.method
("fastBM"
or "sim.corrs"
; see fastBM
and sim.corrs
); method
("by.node"
or "by.branch"
indicating whether to assume the rate varies as a function of the node state or the mean branch state); message
- a logical value indicating whether or not to return corr
and method
; finally logarithm
- indicating whether or not to fit a model in which the variance of Brownian evolution in y
changes as a multiplicative function of x
. The default is logarithm=FALSE
. Value
This function returns a list with up to the following four elements:
- beta
- value of the regression coefficient for square of the contrasts in
y
regressed on the ancestral or branch-wise estimated states for x
. - r
- correlation coefficient for
corr=corr
. - corr
- string giving the value of
corr
. - method
- string giving the value of
method
.
References
Revell, L. J. (2012) phytools: An R package for phylogenetic comparative biology (and other things). Methods Ecol. Evol., 3, 217-223.