[Taxacom] "Natural" groups

[Frederick W. Schueler]

On 12/21/2010 11:41 PM, Kenneth Kinman wrote:

>      The idea of monophyly in the broad sense
> (including both holophyly and paraphyly) being the basis of natural
> classifications and natural taxa goes all the way back to Darwin.

* and all the way back to Linnaeus before that, before anybody knew what 
"natural" really meant.

Back before cladistic terminology was taught to undergraduates, in the 
1960s, "natural" groups were taught as being recognized by their 
polythetic character, as opposed to monothetic artificial 
classifications (archetypically Linneaus' taxa based on counts of sexual 
parts), which were based on single characters. Linneaus' recognition 
that some polythetic groups were somehow "natural" was taught as a 
precursor to evolution.

> ------------------------------------------------------------
> Barry Roth wrote:
>       Use of the term "natural group" goes back a long way, to before the
> art or science of estimating phylogenetic relationships was very far
> advanced. It would be interesting to see some definitions from, say, the
> 1920s. Has that term always implied monophyletic (in the broad sense,
> paraphyly having become a concern later) groups?

* it would be an interesting project to compile a history of definitions 
of a "natural" group, though this would have to be done jointly with 
"monophyletic." I remember being horrified as an undergraduate by George 
Gaylord Simpsons's inclusion of polyphyletic  among monophyletic taxa, 
so long as the poly-ancestors were in the same taxon of the same or 
lower rank as the descendant taxon.

fred schueler
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