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RE: Classification: A Definition



> The bottom line, I think, is that there are only two kinds of taxa:
> clades, and The Other Kind Of Taxon (hereafter TOKOT).  A TOKOT is a
> convenient is defined as "the group of all organisms that are
> sufficiently similar to _this_ one" and for the purposes of acting as
> a clade specified is precisely equivalent to that one anointed
> specimen.

> You _could_ argue that TOKOTs should be abolished completely and all
> biology done in terms of specimens and clades only.  But that is never
> going to happen and to be honest I wouldn't want it to.  I like the
> convenient of TOKOTs.  I prefer the name "Brachiosaurus" to the
> specimen number FMNH P 25017.

One of my beefs with exclusively phylogenetic nomenclature is that it
effectively does away with the TOKOT, as Mike calls it, except at
species level. While this may not be a problem from the idealistic
viewpoint, it potentially has serious consequences from the pragmatic
viewpoint. A significant proportion of currently recognised taxa
(indeed, probably even the _majority_ of currently recognised taxa when
you consider invertebrates, protists, etc.) are not directly based on
evolutionary relationships. We all hope and usually expect that said
taxa reflect evolutionary relationships, but this has not yet been
explicitly tested in far too many cases, and in far too many cases it is
unlikely to be tested in the easily foreseeable future. In the meantime,
it is very convenient to use a system of nested groups reflecting
overall similarity, especially if we understand that these are yet to be
tested. I personally work on members of an invertebrate "infraorder"
that contains over 500 species, of which probably less than twenty have
been included in any sort of phylogenetic analysis. To have this group
reduced to a list of _incertae sedis_ taxa would make things very
difficult - where would I start?

I personally would hate to see phylogeny made an obligatory part of
taxonomy. Firstly, because there are taxa out there that are
taxonomically distinguishable (due to possessing unique characters), but
may not be reliably placed in a phylogenetic analysis at present (due to
shortage of material or some such reason). Secondly, because I have
encountered numerous workers who are excellent taxonomists but ghastly
phylogeneticists (and vice versa, for that matter). And thirdly, because
preliminary non-phylogenetic taxonomy is the primary substrate on which
most phylogenetic studies are built - the recognition of a group is just
inspires workers to test said group.

    Cheers,

        Christopher Taylor

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