The ``ACDC'' (accelerated/decelerated) model assumes that continuous traits evolve under a Brownian motion model which rates accelerates (if \(g\) < 1) or decelerates (if \(g\) > 1) through time. If \(g\) = 1, then the model reduces to a Brownian motion model.
corBlomberg(value, phy, form = ~1, fixed = FALSE)
# S3 method for corBlomberg
corMatrix(object, covariate = getCovariate(object),
corr = TRUE, ...)
# S3 method for corBlomberg
coef(object, unconstrained = TRUE, …)the (initial) value of the parameter \(g\).
an object of class "phylo".
(ignored).
a logical specifying whether gls should
estimate \(\gamma\) (the default) or keep it fixed.
an (initialized) object of class "corBlomberg".
(ignored).
a logical value specifying whether to return the correlation matrix (the default) or the variance-covariance matrix.
a logical value. If TRUE (the default),
the coefficients are returned in unconstrained form (the same used
in the optimization algorithm). If FALSE the coefficients are
returned in ``natural'', possibly constrained, form.
further arguments passed to or from other methods.
an object of class "corBlomberg", the coefficients from an
object of this class, or the correlation matrix of an initialized
object of this class. In most situations, only corBlomberg will
be called by the user.
Blomberg, S. P., Garland, Jr, T., and Ives, A. R. (2003) Testing for phylogenetic signal in comparative data: behavioral traits are more labile. Evolution, 57, 717--745.