Keys vs dendograms

[Mike Dallwitz]

                                                             28 October 1998

> From: Claude Godin <godinc at EM.AGR.CA>
> To: TAXACOM

> I'm trying to find the best ways to build a taxonomic key for a limited
> group of aphid species. I have gathered plenty of details on each
> species, and want to sort out this information.

> I'm not familiar with dendograms (and programs to work with), but it is
> certainly something that has been tried for taxonomic purpose. Any
> experience with this, good or bad?

Dendrograms can be used to present classifications, phylogenies, and keys.
It's not clear which purpose you have in mind.

There are various ways of presenting conventional keys, for example, the
'indented' and 'bracketted' styles, HTML files with links to the leads, and
dendrograms. These variants can offer, at most, comparatively minor
differences in ease of use. The basic process of identification is the same.

Interactive keys have many significant advantages over conventional keys.
For a discussion, see

    Dallwitz, M. J., Paine, T. A., and Zurcher, E. J. (1998). Interactive
    keys. In `Information Technology, Plant Pathology and Biodiversity', pp.
    201-212. (Eds P. Bridge, P. Jeffries, D. R. Morse, and P. R. Scott.)
    (CAB International: Wallingford.)

In addition, the interactive key program Intkey provides many facilities to
help the taxonomist "sort out [the] information". For example, you can find
the differences and similarities between two or more taxa, how well each
taxon is separated from the others, and the distribution of character states
among the taxa. From the same data used to generate the interactive key, you
can also generate conventional keys, and carry out phenetic and cladistic
analyses (including the production of dendrograms).

Mike Dallwitz

CSIRO Division of Entomology, GPO Box 1700, Canberra ACT 2601, Australia
Email: md at ento.csiro.au. Phone: +61 2 6246 4075. Fax: +61 2 6246 4000