[Taxacom] On genera, splitting and ranking

Ken Kinman kinman at hotmail.com
Sat Jul 13 17:48:25 CDT 2013



      Oh, I agree that taxonomic classifications are subjective, but that seems preferable to putting them in an objective "strait jacket" based on age.  You might get a little more information (age of origin), but I think most people are more concerned about stability and usefulness (and thus will continue to reject Hennig's suggestion).


      If the entomologists want to establish an age of origin criterion for Class Insecta, be my guest.  But I don't see much of a problem if a mammal family is much younger than an insect family, and the latter much younger than a bacterial family.  It's only a problem if one is overly concerned with their ages of origin (which most people clearly are not).  Bacteriologists might want to try to establish an age criterion for prokaryotic ranks as well.  Would be interesting to see how successful it would be within those groups.  However, I cannot imagine a single age criterion working across all organisms, as the cost (instability and loss of usefulness) would far outweigh the benefit (knowing a taxon's age of origin directly from its rank).  


                    -------------Ken Kinman


From: xelaalex at cox.net
To: kinman at hotmail.com; kim at kimvdlinde.com; taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] On genera, splitting and ranking
Date: Sat, 13 Jul 2013 15:20:04 -0400

Sorry, Ken,
Perhaps there may be lots more genera of prokaryotes to be recognized depending on whether those groups are really that old. Yes, the clade as a whole maybe old, but the groups that exist today may be very recent.
And that is NOT “absurd” as it immediately tell you that these are really old groups.
Yes, we would have our status reduced in the sense many more species would be included in the genus Homo
or we could change the age criterion so there would be many more genera recognized for Drosophila groups, like Sophophora for melanogaster.
BUT the result would be scientific units useful for comparison.
This exchange began with the question of what is a genus. And yes, your answer of what ever any one wants to call a genus is a genus is fine, but it isn’t science nor very useful.
But as I said as Hennig long ago recognized, there is no Science in taxonomic classifications just subjective opinions.
Oh, well ... 


From: Ken Kinman 
Sent: Saturday, July 13, 2013 3:01 PM
To: Chris Thompson ; Kim van der Linde ; taxacom at mailman.nhm.ku.edu 
Subject: RE: [Taxacom] On genera, splitting and ranking

Hi Chris,
           Well, the fossil record of prokaryotes goes back billions of years, so if there are prokaryotic genera that old, why is it useful to maintain a much younger genus Drosophila?    If you have a consistent yardstick across all living organisms, all the vertebrates would probably end up in one genus.  Then you would need a bunch of new infrageneric ranks just to classify vertebrates.  
           Thus, applying a consistent yardstick would destroy the utility of our classifications.  And basing the yardstick on Homo or even Drosophila wouldn't help, because the number of prokaryotic taxa and ranks would explode to an absurd degree.  Either way it would lead to either absurd splitting or lumping, so one clearly needs periodic anagenetic breaks to maintain the utility of classifications.  

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