[Taxacom] Biodiversity questions: Classifications

Fri Oct 4 08:22:33 CDT 2013

Hi Dick,

       I agree.  And I think anyone who has tried to apply Hennig's criterion (in particular) for a variety of taxa has experienced that disappointment.  I don't think Hennig's idea has been universally ignored so much as it just doesn't work in practice.  It might work for Diptera, but that taxon is atypical (my classification of Diptera which I posted on Taxacom some years ago had almost no paraphyly at all).

       Chris mentioned Phylum Psychozoa, but I believe that Huxley only made that proposal as a joke (to make a point).  Family Hominidae (sensu stricto) has worked very well for decades, and separating it from Phylum Chordata would be paraphyly to an absurd degree.  Paraphyly is a useful tool, but it must not be abused or overly used.

                  -----------------Ken  

Date: Fri, 4 Oct 2013 08:24:45 -0400
Subject: Re: [Taxacom] Biodiversity questions: Classifications
From: rjensen at saintmarys.edu
To: xelaalex at cox.net
CC: kinman at hotmail.com; muscapaul at gmail.com; taxacom at mailman.nhm.ku.edu

Chris,

While consistent (do you mean precise?) measure are used in much of science, good science does not require such measures.  Many sources of data, which lend themselves nicely to valid statistical evaluation, are based on qualitative measures.  

If you require that taxonomy needs a consistent degree of morphological, ecological, behavioral, or genetic divergence for each taxonomic rank, then you will be disappointed.  While this is, perhaps, a legitimate goal, I'm not convinced it is workable across the tree of life.

Cheers,

Dick J

On Thu, Oct 3, 2013 at 10:12 PM, Chris Thompson <xelaalex at cox.net> wrote:

Sorry, Ken,

Yes, your proposal is fine, but is not Science.

Yes, you can say some families are the same, and that other families are not the same as they may be equal to subfamilies or superfamilies. Some subfamilies are the same but others are equal to superfamilies or families. Et cetera.

Science needs consistent measures. A meter or an ounce need to be the same across all hypotheses. Likewise, if one wants to make scientific hypotheses about biodiversity the groups need to be the same, representing a measure of the same underlying component, etc.

Oh, well ...

Chris

From: Ken Kinman
Sent: Thursday, October 03, 2013 5:48 PM
To: Chris Thompson ; muscapaul ; taxacom at mailman.nhm.ku.edu
Subject: RE: [Taxacom] Biodiversity questions: Classifications

Hi Chris,

       I hope Paul will respond to your post, as I thought it was an excellent point that needs to be answered and discussed more thoroughly and directly.

       As far as higher classifications having no information bearing on biodiversity, I can think of one solution to that supposed problem.  Although the clades being compared should be roughly the same age, there is no reason that those clades need to be the same rank.  Family Hominidae (sensu stricto) could be compared to the subfamilies of Family Pongidae.  And your older dipteran family could be compared to Superfamily Carnoidea or an even more inclusive clade.  There are solutions that are less drastic than adopting Hennig's age of origin criterion, and perhaps that is why Hennig's proposed criterion has been ignored for decades.

             -----------------Ken

--------------------------------------------------------------------------------------------------------

> From: xelaalex at cox.net
> To: muscapaul at gmail.com; taxacom at mailman.nhm.ku.edu
> Date: Thu, 3 Oct 2013 11:15:30 -0400
> Subject: Re: [Taxacom] Biodiversity questions: Classifications
>
> PAUL:
>
> The scientific question that we begin with was about biodiversity.
>
> And Hennig said to answer those kinds of questions, then groups based on
> time are the best.
>
> So, under the Hennig system, one could say that family X which now contains
> 999 species is more biodiversity, has more speciation, etc., than family Z
> which now contains only 1 species. BECAUSE the contents (species) of each
> family represents a clade that has evolved over the SAME time period.
>
> But as I indicated in my Diptera example, comparison of the number of
> species in Limoniidae versus Inbiomyiidae does not tell you anything about
> biodiversity, speciation, etc. because those groups are not equivalent, not
> comparable, etc.
>
> Oh, well ...
>
> Sincerely,
>
> Chris
>
> -----Original Message-----
> From: muscapaul
> Sent: Thursday, October 03, 2013 10:27 AM
> To: TAXACOM
> Subject: Re: [Taxacom] Biodiversity questions: Classifications
>
> Just out of interest: If actual age would (should?) be playing a role,
> where do we then account for differences between taxa with highly divergent
> generation time, like drosophilids with perhaps more than 10 generations
> per year under favourable conditions and panthophthalmids which probably
> take multiple years to develop? And then I am just considering taxa within
> the same order where one might give rise to new taxa on a much shorter
> absolute time scale than the other.
>
> Paul
>
> On 3 October 2013 12:59, Chris Thompson <xelaalex at cox.net> wrote:
>
> > So, for example, in Diptera, we now recognize a family which is a clade of
> > some 10 thousand species and of some 200 million years old (Limoniidae)
> > and
> > another family of less than a dozen species and probably less than 5
> > million
> > years old (Inbiomyiidae).
>
> ...
> >
> > So, if one wants to derived scientific hypotheses from classifications,
> > one
> > must go back to clades and their age.
> >
> > Sincerely,
> >
> > Chris
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