I wish I could take credit for that comment but I believe it was John K.
Tucker. This has become a fascinating topic. It seems that, even with DNA
analyses available, that the subject of subspecies is very much unresolved.


-----Original Message-----
From: Conchologists List [mailto:[log in to unmask]] On Behalf Of
Frederick W. Schueler
Sent: Wednesday, July 15, 2009 11:06 PM
To: [log in to unmask]
Subject: Re: [CONCH-L] M. corona

Pete Krull quoted:

> Wilson & Brown were not herpetologists and certainly not snake scale
> counters.

* but they were myrmecologists, in an era in which Ants were beset with
infraspecific taxa to an inordinate degree.

> Many many turtle, snake and lizard subspecies have areas where they
> intergrade.

* Brown's Rule only applies to cases where the zone of intergradation hasn't
been studied, and the subspecies lines are drawn in breaks in the variation,
which also happen to be breaks in the available specimens.

> The Eastern Box turtle is an excellent example.
> It has an eastern race: /Terrapene carolina carolina/, a three-toed
> race: /T. c. triunguis/, the Gulf Coast race: /T. c. major/, and a
> Floridian race: /T. c. baueri/.  The ranges are contiguous and there
> are extensive intergrade zones.  However, few if any herpetologists
> would use that as a good reason to call them all /Terrapene carolina/.

* in many cases, these are just cases of gradual geographic variation, as
when some scale count is the only classical quantitative feature on a Snake,
and there's no indication that the variation in the one of the few features
which can be assessed really delimits taxonomically significant portions of
the species. In other cases, they're species complexes, without any
significant gene flow among the species, even when there are some hybrids
found (as in Leopard Frogs).

Jim Rising and I suggested (Schueler and Rising. 1976. Phenetic evidence of
natural hybridization.  Systematic Zoology 25:283-289) that only when
there's increased variability in a zone of free intergradation should the
variation be used to delimit subspecies, since the increased variability
indicates that the intergrades are hybrids, and the "hybridity" indicates
that the hybridizing entities are "real" taxa.
This hasn't been widely accepted. From what I know of them, I suspect that
the Terrapene carolina case is one of "real" subspecies: taxa which are as
different as species might be, but hybridize where they come into contact.

> The problem with /Melongena corona/ (/sensu lato/) is that in the
> Recent its range is more or less linear.  However, during the
> Pleistocene there had to be several times where this linear array was
> disrupted and then rejoined.  Many of the problems likely result from
> that.  I think including all king crowns in /M. corona/ would be just
> as wrong as considering all eastern box turtles, /T. carolina/.  Just
> because something is hard does not mean it should be avoided.

* but the subspecies is the only infraspecific category recognized in
zoology. It was developed by ornithologists working with continuous or
contiguous continental (2-d) variation among Bird populations, and various
other zoologists, who often work with very different kinds of
among-population variation, are stuck with it. Botanists have more freedom
with formal categories, but in one-dimensional or ecophenotypic or complexly
2-d cases, zoologists, whether they "believe" in subspecies or not, have got
to fall back on the informal names which Wilson & Brown recommend be used
for classes of similar populations that one wishes to discuss.

> Finally for all those interested in attributing variation in shell
> morphology in /M. corona/ to some ecotypic magic.  I would ask that
> you please demonstrate this experimentally.  If /M. sprucecreekensis/
> does not have oysters to eat, I think it starves rather than growing
> up to be an /M. c. altispira.  /

* this would suggest that these are species, however genetically homogeneous
their mitochondria may be.

fred.
------------------------------------------------------------
            Bishops Mills Natural History Centre
          Frederick W. Schueler & Aleta Karstad
       RR#2 Bishops Mills, Ontario, Canada K0G 1T0
    on the Smiths Falls Limestone Plain 44* 52'N 75* 42'W
      (613)258-3107 <bckcdb at istar.ca> http://pinicola.ca
------------------------------------------------------------
If we'd been meant to refer to species by made-up vernacular names, God
wouldn't have created Linnaeus!
------------------------------------------------------------

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