[Taxacom] Biodiversity questions: Classifications

[John Noyes]

Hi Chris,

I completely agree with you.

If not the age of the group, then how about standardising it as a theoretical average number of generations per species, or some sort of index of hypothetical generation time, or index of generation time x genetic plasticity, or generation time x genetic plasticity  + perceived rate of extinction, or . . . . 

My brain hurts.

John

John Noyes
Scientific Associate
Department of Life Sciences
Natural History Museum
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-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Chris Thompson
Sent: 03 October 2013 19:04
To: Richard Jensen
Cc: TAXACOM
Subject: Re: [Taxacom] Biodiversity questions: Classifications

Sorry, Dick,

Yes, for different questions, we as scientists may use different measures, etc.

HOWEVER, it the case of your example, age-based ranked groups are also useful. For CURRENT biodiversity one would declare that family x with 999 surviving species is a highly successful clade, where as family z with only a single surviving species is NOT.


Real example, horse-shoe crabs versus insects!

Oh, well ... 

From: Richard Jensen 
Sent: Thursday, October 03, 2013 12:28 PM
To: Chris Thompson 
Cc: muscapaul ; TAXACOM 
Subject: Re: [Taxacom] Biodiversity questions: Classifications

Could it be that the apparent discrepancy in biodiversity, as we perceive it, is that family Z has had just as many speciation events as family X, but has experienced extremely high rates of extinction?  If so, then knowing the age tells us nothing about biodiversity - the two clades, one with 999 surviving species, and one with 1 surviving species, could be the same age.


Dick J




On Thu, Oct 3, 2013 at 11:15 AM, Chris Thompson <xelaalex at cox.net> wrote:

  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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-- 

Richard Jensen, Professor

Department of Biology

Saint Mary's College

Notre Dame, IN 46556
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