Polyphyly, etc

[Don.Colless at CSIRO.AU]

George Esterbrook's notion of "convex" groups is surely the neatest way
of distinguishing between paraphyly and polyphyly. It can be easily
illustrated on a tree, where (as James Adams points out)  a paraphyletic
group is convex - its members are all connected on the tree without
passing through ancestor(s) of any other group. Members of a (concave)
polyphyletic group can only be connected via ancestors of some other
group. 


Don Colless,
Div of Entomology, CSIRO,
GPO Box 1700,
Canberra. 2601.
Email: don.colless at csiro.au
Tuz li munz est miens envirun