phylogenies

Don.Colless at CSIRO.AU Don.Colless at CSIRO.AU
Fri Oct 1 18:17:17 CDT 2004


Richard Pyle would like a language "optimised to communicate phylogenies" - without, I take it, driving us into something like Phylocode. There is such a device - it's called a cladogram and it's absolutely succinct and explicit. It does not have to be a tree-like diagram on paper: for n terminal nodes, a list of 2n-1 numbers provides all the information. The nth number is the label of the nth node, terminal or internal. A similar list will give the lengths of all internodes. Earlier users of PAUP will recognise this "ancestor function" (invented by Steve Farris). It takes only a few minutes with pen and paper to recreate a quite substantial diagram - not much if you really need the information, and saves a lot of classificatory conflict.

Someone also noted the "objectivity" gained when, say, members of species X are found to parasitise only members of species Y. It goes beyond the species level: e.g., as far as I know, all species of the fungus gnat genus, Heteropterna, rest as adults on spiders' webs, deftly mimicking bundles of prey; all species of the dipterous family Tachinidae parasitise other insects (and those of tribe Proseniini parasitise only beetle larvae); and so on. Technically, this seems to be what is called consilience (although I think Ed Wilson pushed it a bit too far!!).

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




More information about the Taxacom mailing list