[Taxacom] taxonomic resistance? (was Re: Phylocode vs Linnean)

Sun Apr 17 06:43:09 CDT 2011

Call me confused. I thought that rank-based systems use similarity to 
group taxa. And that this often but not always (paraphyletic taxa for 
example) corresponds with major clades in the phylogenetic tree. The 
main difference between phylocode and rank-based systems is that 
phylocode does not care that a two species with different generic names 
are within the same clade called Drosophila, while the rank-based system 
requires remaining species and clades to reflect the latest updates to 
our insights.

I do not think that updating names each and every time there is a new 
phylogeny (like updating Aedes aegypti based on a single large cladistic 
analysis), but once stability is achieved (like in Drosophila, the major 
topology has not changed since Thorckmorton in 1975) I think updating 
the stuff might be wise. Which at that time is most likely a one time 
endeavor after which the names will be stable AND reflective of decent.

It is unfortunate that we are now playing catch up with our 
understanding of the relationships within the tree of life, but once we 
get to a stabilization of that, stability will greatly improve. The 
question we have to ask us is whether we want names to remain reflecting 
the past insights of similarity, or that we want to adjust those to to 
total sum of our knowledge regarding those relationships.

Kim

On 4/16/2011 10:51 PM, Stephen Thorpe wrote:
> the basic problem here is the absurd notion that binomials have to reflect
> phylogeny, when we want/need the binomials to be stable and known, but the
> phylogeny can be highly unstable and at least in part unknowable!
>
>
> ... cake and eat it too ...
>
> Stephen
>
>
>
> ________________________________
> From: Kim van der Linde<kim at kimvdlinde.com>
> To: Karl Magnacca<kmagnacca at wesleyan.edu>
> Cc: taxacom at mailman.nhm.ku.edu
> Sent: Sun, 17 April, 2011 2:42:57 PM
> Subject: Re: [Taxacom] taxonomic resistance? (was Re: Phylocode vs Linnean)
>
>
>
> On 4/16/2011 4:42 PM, Karl Magnacca wrote:
>> I don't really think that 1) providing diagnosable characters for
>> the proposed genera, such that they can be separated with a
>> dichotomous key, 2) being clear about exactly which species go into
>> which new genus, and 3) resolving the status of ~100 species that
>> aren't currently placed to species group and would be left without
>> generic assignment, are either arbitrary or a particularly high
>> threshold.  It's kind of basic, actually.  Anybody here disagree?
>
> Well, lets see.
>
> 1) Drosophila is now defined as not anything else. There is no single
> characteristic that can be used in a dichotomous keys. This will be a
> lot better for the split genera.
>
> 2) That is crystal clear for the new genera.
>
> 3) This is one of those absurd demands, as genera are split all the time
> without demanding this. But more important, it is absurd to claim that
> those species won't have a generic name after a split, as they already
> do have a generic name, namely Drosophila. Unless they are actively
> moved to another genus, they will remain within Drosophila until their
> status is resolved. Furthermore, many of those species might never be
> resolved for various reasons, such as missing type species with obscure
> and ambiguous descriptions, etc., and holding any revision hostage
> because of this demand is something I never have seen except in the
> demands for the revision of the genus Drosophila.
>
>>> Anyway, for the time being, phylocode is what rules the genus
>>> Drosophila sensu lato.
>>
>> This is just an absurd statement.  Athough it does make a sort of
>> sense, in that a few people have proposed generic names for "clades"
>> that are dissociated from the species binomials (PhyloCode Art. 21),
>> and are completely ignored in actual usage.
>
> Well, you are right, it is not to the letter of phylocode, but the
> central idea that clades are defined by concept and not content, this
> holds, because the de facto definition of Drosophila is as follows:
>
> Drosophila refers to the crown clade originating from the most recent
> common ancestor of Drosophila (originally Musca) funebris (Fabricius,
> 1787) and Drosophila melanogaster Meigen, 1830. This definition is
> node-based and designates a crown clade.  Abbreviated definition:
> Drosophila =<  Drosophila (originally Musca) funebris (Fabricius, 1787)
> &  Drosophila melanogaster Meigen, 1830.
>
> Call it what you want to call it, it does not change that the de facto
> used clade called Drosophila includes ten plus other genera that are
> primarily positioned within the various subgenera. Anyway, call the mess
> what you want.
>
> Kim
>
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