[Taxacom] On genera, splitting and ranking

Richard Pyle deepreef at bishopmuseum.org
Sat Jul 13 20:27:03 CDT 2013


“Monophyly”, by itself, is not a “test” for determining if a particular group of organisms constitutes a group at some particular rank.  As far as we know, every living thing on the planet is monophyletic.  You could use monophyly as a criterion to determine whether organism “X” belongs in established genus “A” or established genus “B”, but you cannot use monophyly to determine whether group “A” should be regarded as the same genus as group “B” (lumper), or as a distinct genus (splitter).

 

Rich

 

From: Stephen Thorpe [mailto:stephen_thorpe at yahoo.co.nz] 
Sent: Saturday, July 13, 2013 2:31 PM
To: Chris Thompson; Scott Thomson; Taxacom; Richard Pyle
Subject: Re: [Taxacom] On genera, splitting and ranking

 

I think that genera (and higher) categories are still "testable", if monophyly is a requirement. They can be refuted, but there may be many equally acceptable monophyletic alternatives depending on lumping/splitting. Similarly, for species, if a proposed species was found to be based on an aberration, then this would refute the proposal, but I'm not sure you can prove that a species is a species, any more than you can prove that a genus is a genus, you can only hope to disprove ...

 

Stephen

 

From: Chris Thompson <xelaalex at cox.net>
To: Stephen Thorpe <stephen_thorpe at yahoo.co.nz>; Scott Thomson <scott.thomson321 at gmail.com>; Taxacom <taxacom at mailman.nhm.ku.edu> 
Sent: Saturday, 13 July 2013 11:35 PM
Subject: Re: [Taxacom] On genera, splitting and ranking

 

Sorry, Stephen,

 

if Rich’s main point also applies to SPECIES, then my comments are out of line.

 

Yes, there are various definition of SPECIES now, but all underlie a scientific approach to defining what a species is. So, a species is a scientific hypothesis which can be tested, etc. So, in term of Science, species are objective.

 

In terms of higher categories (that is, above species) where are the underlying scientific definitions? 

 

So, how does one test whether Drosophilia or Sophophora is a better / more well supported hypothesis?

 

One can test monophyly and both are apparently monophyletic, but when in comes to RANK, whether one is a valid genus or subgenus, what criteria does one test?

 

Yes, Hennig once did propose a testable criterion for rank, that is, age of origin. However, everyone, including Hennig himself, rejected that criterion.

 

Age is a wonderful and scientific criterion for rank. If we had such, then we could easily propose that higher Diptera (Cyclorrhapha, a suborder) is the same as birds (Aves, a Class) and far more diverse [Yes, the little creatures with narrow specialization generate more species, than larger more generalized predators, etc.]. But these kinds of scientific questions are not now possible due to the distorted system of classification we have and used.

 

And the worst, the genus Homo would if one accepted age-based definitions be greatly broaden to conform to other groups and species, so we would have many more fellow species, etc.! But then again, we could change the age limit definition of genera to ensure that Homo remains restricted to sapiens and closely related fossils, which would mean hundred of thousands of new genera would be needed for the rest of the animal world. [and I am sure the plant world would also be disrupted, etc., too]

 

Oh, well ...

 

Sincerely,

 

Chris

 

from home

 

From: Stephen Thorpe <mailto:stephen_thorpe at yahoo.co.nz>  

Sent: Friday, July 12, 2013 9:19 PM

To: Chris Thompson <mailto:xelaalex at cox.net>  ; Scott Thomson <mailto:scott.thomson321 at gmail.com>  ; Taxacom <mailto:taxacom at mailman.nhm.ku.edu>  

Subject: Re: [Taxacom] On genera, splitting and ranking

 

I think you may have missed Rich's main point, Chris? He was applying it also to SPECIES, which is where I am not so sure ...

 

Stephen

 

From: Chris Thompson <xelaalex at cox.net>
To: Scott Thomson <scott.thomson321 at gmail.com>; Taxacom <taxacom at mailman.nhm.ku.edu> 
Sent: Saturday, 13 July 2013 1:11 PM
Subject: Re: [Taxacom] On genera, splitting and ranking


ALL;

This is a great thread, etc.

As Rich Pyle indicated, it is not only genera but all higher categories.

When one examines the historical record, we clearly see the trend to 
continue to split more finely and to create NEW taxa.

And today with impact factors, etc., it is critical to publish NEW 
information, etc.

So, today as yesterday, the reward is on publishing NEW, and that means in 
reference to higher groups, splitting existing concepts.

And it is clear as Hennig years ago pointed out, there is NOTHING Scientific 
about the current trend in splitting, etc. There is NO objective SCIENTIFIC 
standard for ranking of taxonomic categories.

So what in one part of the clade (Diptera) would meanly be considered a 
genus, in another part of the clade is ranked as a family (Inbiomyiidae).

What is clear in Diptera, IS when there are general users, the public, 
biologists, etc., and for them the generic concept remains conservative.

So, most still accept, for example, AEDES, for the common vectors of various 
disease; or DROSOPHILA for melanogaster, the genetic model, etc.,
instead of the split classifications of Stegomyia or Sophophora.

Oh, well ...

Sincerely,

Chris

from home



-----Original Message----- 
From: Scott Thomson
Sent: Friday, July 12, 2013 1:53 PM
To: Taxacom
Subject: Re: [Taxacom] On genera

This thread seems to have been split, but I wanted to reply to this part of
it also. I also agree that this is what we currently do. I think it was
this comment I was referring to when I mentioned splitting and lumping in
the other thread. My personal view is that a lot of thought should go into
wether or not to describe a genus, significant evidence, and much more than
I often see should be presented to demonstrate the need for a genus.
Equally there should not be fear, or bias, or whatever it is against
lumping genera. I am hopeful that we can eventually get to a better
definition of the genus. But its not there yet.

Cheers, Scott


On Fri, Jul 12, 2013 at 1:25 PM, Richard Pyle 
<deepreef at bishopmuseum.org>wrote:

>
> I completely agree with Jason on this:
>
> > I would strongly agree that it is a taxonomic convenience so we can
> > communicate better and break down biodiversity for our understanding. I
> > would disagree with the need for monophyly though, and rather push for
> > non-polyphyletic genera, at least until taxonomists show some restraint
> > naming genera, or at least an equal enthusiasm for synonymizing them.
>
> Moreover, I would extend this to all taxonomic ranks.
>
> Aloha,
> Rich
>
> P.S. Yes, I meant *all*.
>
>
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