I presume that most people on the Taxacom list are aware of this paper - http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0016410 . I was wondering if contamination is a more general problem affecting molecular phylogenies. It might explain one that I saw with an African species nested within a set of apparently unrelated North American species. Lynn Raw