Re: Species [arbitrary to a degree]

["Jaime A. Headden" <qilongia@yahoo.com>]

Ken Kinman (kinman@hotmail.com) wrote:
 
<I do think of a ring species as a populations of genes.  In the case of 
circumpolar gulls, their
physical mobility would naturally make the mobility of genes easier as well.>

  And reduces the existence of a ring species to just a series of populations, 
some of which
affect other species than the majority. Nothing unique in a circumpolar bird or 
mammal for which
species have been establish. Except for which there are corroboratory data for 
the distinction of
a species (plumage, proportions, behavior, etc.), using a genetic population 
isolation criterion,
ring species are a single species.

<However, if you have a "ring species" of something like a gopher (or  other 
rodent that has a
small individual home range), the mobility of genes can be greatly impaired.  
As long as some gene
flow continues through the intervening populations of the ring, I would still 
regard it as a
single species.>

  I would agree with Ken on this.

<Once gene flow is completely impeded at some point within the ring, the 
process of speciation
tends to speed up considerably, but if there is a potential for the "impedance" 
to reverse itself,
there is always the possibility for gene flow to resume.  This demonstrates how 
fuzzy species can
be at the edges (especially in the time dimension).  Whether a given 
"impedance" will cause
speciation is subject to vagaries of historical contingencies if the situation 
might be reversed
before it is too late.>

  Yet there continues to be a distinguishing cause in neontologists to 
recognize these as "genera"
and "species" and uphold ranks, in spite of the variable genetics of 
populations.

  Hypothetically, if you took a ring species of swallows in Europe, based 
around the Alps, and
made the ring a perfect circle divided into 360degs., and made each degree a 
single population,
one could easily say that at every 180deg pair, each population would appear to 
be a unique
species to it's polar opposite. Hence, each population should be recognized as 
it's own species,
or subspecies, based on genetic flow and population metrics. Each group will 
have a slightly
different ecology based on location, some may be highland or montane birds, 
others lowland, field
or cohabitating [with man] or near-estuarine birds. Each population or flock 
would be in itself
isolated. But the nature of such groups of birds is to fly to another flock to 
breed, rather than
isolate itself. Such is the nature of genetic dispersal, and preventing 
insularity in population
genetics, so that a genome is not "stiltified" or lost.

<Luckily only a small percentage of species will give us such problems at a 
given time in
evolutionary history (such as the present time), but they do demonstrate one of 
the reasons why
the species problem is so difficult and controversial.>

  Ken and I see this differently. I feel that perhaps "ring species" are more 
elucidating then
they are problematic, in that they show the tru interation of cross-breedable 
populations and the
intrinsic fuzziness of species. Identification of a rank species would seem to 
suggest, as was the
intent, a complete and absolute division which was never crossed. Recent tests 
and the abscence of
a universal anagenesis show that there cannot ever be a universal definition of 
a species, and
perhaps the absolute dropping of not just the idea of the rank, but the idea of 
the species,
should be entertained. One can find criteria for identifying populations, which 
seem to be the
best way to group animals at the most intrinsic level above the individual. 
This would also work
for fossils, of which we find unique morphological organisms which do not 
likely pertain to a
previously known population. We can identify the fossil organisms by a unique 
binomial for each
organism, each and every one; Jon Wagner offers a single uninomial, but the 
historic preferrence
has been to two. That the spirit of deQuieroz' and Jon's suggestion be 
retained, we can follow the
case of Flynn et al., last year in JVP, in the diagnosis of a "taxon" 
identified by a bionomial
unique to one animal, and only one animal; this may end up resulting in the 
identification of each
species unique to it's neighbors by a plethora of really unwanted primary 
binominate word
(formerly, genus). I suspect that this is what leads Jon and Kevin de Quieroz 
to a single name,
rather than two, based on the extensive task of recognizing many new names. Not 
only would there
be a *Maiasaura peeblesorum,* but *Edmontosaurus annectens* would also need a 
new primary name.
"Wagneria"?

  Neontology recognizes species as subsets of genera, so that the binomial is 
not a unique name
for a species, but an indication of nesting. Fossils cannot be compared to the 
same degree as a
living, breathing *Ochotona* [pika] or *Passer* [sparrow], much as we would 
wish they could. But
to make a system that must work for both equally may be overly simplifying a 
much more diverse and
complex issue that cannot in any way be simplified as such.


=====
Jaime A. Headden

  Aaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhr-gen-ti-na
  Where the Wind Comes Sweeping Down the Pampas!!!!

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