[Taxacom] On genera, splitting and ranking

John Grehan calabar.john at gmail.com
Sat Jul 13 09:47:39 CDT 2013


The trouble with age is that we only have minimal estimates available based
on the fossil record (and molecular divergence estimates are just an
extrapolation based on one or other molecular clock model). Most species
don't even have a fossil record.

John Grehan


On Sat, Jul 13, 2013 at 10:38 AM, <Frank.Krell at dmns.org> wrote:

> "Yes, Hennig once did propose a testable criterion for rank, that is, age
> of origin. However, everyone, including Hennig himself, rejected that
> criterion."
>
> Chris, would you remind me where he did so? I just cannot remember that he
> did, but it is long ago that I read all his theoretical works (in German).
>
> "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."
>
> Isn't it amazing that a clear and useful criterion, probably the only
> phylogenetically justifiable criterion to define rank meets with so much
> resistance, rendering comparisons beyond one's small research domain so
> difficult?
> Tradition (Aves is a class, Scarabaeidae is a family) is so much more
> important for emotionally heavily invested scientists than scientific
> reasoning.
>
> And, of course, we have many paraphyletic species, but we should not have
> paraphyletic higher taxa. There is no reason to let the pendulum swing back
> to pre-hennigian times.
>
> Frank
>
> Dr. Frank-T. Krell
> Curator of Entomology
> Commissioner, International Commission on Zoological Nomenclature
> Chair, ICZN ZooBank Committee
> Department of Zoology
> Denver Museum of Nature & Science
> 2001 Colorado Boulevard
> Denver, CO 80205-5798 USA
> Frank.Krell at dmns.org
> Phone: (+1) (303) 370-8244
> Fax: (+1) (303) 331-6492
> http://www.dmns.org/science/museum-scientists/frank-krell
> lab page: http://www.dmns.org/krell-lab
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