phyreg:The Phylogenetic Regression of Grafen (1989)
Provides general linear model facilities (single y-variable, multiple x-variables with arbitrary mixture of
continuous and categorical and arbitrary interactions) for
cross-species data. The method is, however, based on the
nowadays rather uncommon situation in which uncertainty about a
phylogeny is well represented by adopting a single polytomous
tree. The theory is in A. Grafen (1989, Proc. R. Soc. B 326,
119-157) and aims to cope with both recognised phylogeny
(closely related species tend to be similar) and unrecognised
phylogeny (a polytomy usually indicates ignorance about the
true sequence of binary splits).
