[Taxacom] Reptilia (and Hominidae)

Frederick W Schueler bckcdb at istar.ca
Tue Mar 17 13:40:46 CDT 2009

Neil Bell wrote:
> I think it's odd that in all of this lengthy and interesting discussion 
> about monophyly vs. paraphyly in classifications no-one has mentioned 
> rank. Isn't rank clearly the issue, rather than monophyly vs. paraphyly? 

* amen to that, and to what's below. But I think the problem is, to cast 
it in Hegelian terms, that when the thesis of cladistics was struggling 
with the antithesis of phenetics in the 1960s and 1970s, there wasn't 
ever a synthesis that incorporated phenetics' "overall similarity" into 
new systematic procedures. "Holophyly" was such an engaging idea, and 
"overall similarity" was so complex, and so dependent on the character 
set analysed, and then so mixed up between phenotypic and genetic data 
sets, that "overall phenotypic similarity" wasn't widely recognized as a 
stand-in for "ecological similarity" in the same way that "synapomorphy" 
was recognized as a stand-in for "propinquity of descent." Just saying 
"evolutionary systematics" and continuing in the old New Synthesis ways 
didn't count as a new synthesis.

I'm not sure what such a synthesis would look like, and maybe 
old-fashioned phenetics requires too much caliper work to be attractive, 
but I think that ecological similarity would be somehow incorporated in 
a systematics that reflected our best understanding of organisms. --


> Nearly all of the cited cases of evolutionary information being "lost" 
> in monophyletic classifications are where a highly distinctive 
> monophyletic group is derived from within another monophyletic group, 
> the remaining members of which are recognisable by possession of a suite 
> of plesiomorphic characters and have traditionally been recognised as a 
> taxon. Clearly the ideal solution is to name the larger group (including 
> the derived clade), and to also name the derived clade, without then 
> being required to name the otherwise unremarkable sister group of the 
> derived clade (and probably other groups as well) because the larger and 
> smaller groups are of different rank. I just don't get what evolutionary 
> (as opposed to cultural/historical)  information is "lost" by not naming 
> the paraphyletic residue of the larger clade. After all, few people are 
> suddenly going to find themselves unable to recognise (or refer to) a 
> great ape that isn't a human, or a reptile that isn't a bird, just 
> because these paraphyletic groups are no longer named. The very fact 
> that the paraphyly of the traditional group is not immediately obvious 
> from looking at it ensures that it will continue to be recognisable as a 
> group to anyone who wishes to see it. If a classification does not 
> reflect the fact that birds are, actually, birdy reptiles however, then 
> it genuinely is deficient in representing and communicating evolutionary 
> information. Of course taxonomic stability is a different problem; the 
> ideal solution isn't necessarily practical to implement in a given time 
> frame.

             Bishops Mills Natural History Centre
           Frederick W. Schueler & Aleta Karstad
        RR#2 Bishops Mills, Ontario, Canada K0G 1T0
     on the Smiths Falls Limestone Plain 44* 52'N 75* 42'W
       (613)258-3107 <bckcdb at istar.ca> http://pinicola.ca

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