This function identifies the edges that belong to a group (possibly
non-monophyletic) specified as a set of tips.
Usage
which.edge(phy, group)
Arguments
phy
an object of class "phylo".
group
a vector of mode numeric or character specifying the tips
for which the edges are to be identified.
Value
a numeric vector.
Details
The group of tips specified in `group' may be non-monophyletic
(paraphyletic or polyphyletic), in which case all edges from the tips
to their most recent common ancestor are identified.
The identification is made with the indices of the rows of the matrix
`edge' of the tree.