R help - Oct 2008 - dotted lines for branches in ape's plot.phylo?

Hi,

I'm very much enjoying using the ape package to produce phylogenetic  
trees with colored branches (using edge.color). Is it also possible to  
specify that some branches should be drawn as dotted lines? That would  
be really useful.

I've tried messing around with edge.width, but that doesn't seem to  
help me get dotted lines.

thanks,

Janet Young