[Taxacom] Order Campanulales (worth maintaining?)

[Curtis Clark]

On 2011-02-19 15:03, Richard Zander wrote:
> Genera are non-arbitrary because we see them, apprehend them, grok 
> then, vasten them; even Aristotle recognized genera, Linneaus 
> incorporated them into his very names for species. I think it is up to 
> you to subject taxa to a statistical analysis that shows that genera 
> are arbitrary and merely random groups of vaguely similar species.
Okay, I'll try one more time before I drop it.

Although I can't think of one off the top of my head, there are a number 
of genera among the flowering plants, and no doubt elsewhere, that have 
both sensu stricto and sensu lato circumscriptions that are widely 
accepted. Whether one accepts the one or the other in each of these 
cases is most often informed by past practice, one's taxonomic milieu, 
the manuals in use for one's region, and other factors that don't relate 
directly to any traits of the genera or their component species and 
populations, or to any theories about their origins.

So I'm not saying that the generic circumscriptions are arbitrary, but 
rather that the choice between them is arbitrary. And in a similar 
sense, I'm saying that the taxa aren't arbitrary, but their ranks are.

Taking, for now, at face value your assertion that genera evolve, how 
can you even address this without specifying the circumscription? And if 
you specify the circumscription, why does the rank even matter except 
for naming purposes? And do you deny unranked taxa the ability to evolve?

This started out with my assertion that ranks (not taxa) are 
biologically meaningless for anything other than specifying nesting 
(with the exception of species, which I will defend but many won't). 
Although again many will disagree, I fully accept that taxa can evolve. 
You have not convinced me that the rank or lack of rank of a taxon has 
any bearing on this.

-- 
Curtis Clark
Cal Poly Pomona