Subject: Re: species concepts (was VCR Fox Sparrows)
Date: Jun 20 09:49:19 1995
From: Eugene Hunn - hunn at u.washington.edu


Joe et al.,

And not just three species of Homo sapiens, since they only included
three "populations" (actually, probably small samples from each of three
continental areas). By the same logic one could consider each of quite a
number of Hindu caste groups as distinct species. We could have
socioeconomically based class species. Each endogamous rural Mayan
village in the Chiapas highlands would be a species. Where does one draw
the lines?

Gene Hunn.

On Sat, 17 Jun 1995, Joe Morlan wrote:

> David Wright wrote:
>
> > But as I mentioned in a previous message, the BSC has big
> > problems even if you choose reproductive isolation as the
> > most important aspect of speciation. These problems with the
> > BSC were not recognized by its architects because they simply
> > were not all that concerned with genealogic relationships
> > *among* species. That, of course, is at the heart of the
> > cladistic revolution, and it is this revolution that led to
> > critical reappraisal of the BSC. If the BSC was revamped so
> > that it did not produce genealogically nonsensical species,
> > it would look a lot like a PSC that takes into account
> > population genetics (cf. Donoghue's version of the PSC), and
> > a lot like Wiley's ESC. Everything that rises must converge.
>
> There is still a very serious problem with the PSC which David has failed
> to address. The PSC fails to provide a framework for polytypic species.
> The original morphological species concept gave a separate name for each
> morphologically diagnosable population. The PSC brings us back full
> circle to the 19th century. The great power of the biological species
> concept was to provide a framework for describing intraspecific
> geographical variation. The PSC recognizes the tips of the branches of
> every single subspecies of Downy Woodpecker or Song Sparrow as an
> independent species and provides no nomenclatural basis for pointing out
> that they are really just varieties of a single gene pool with extensive
> hybridization in many areas.
>
> Furthermore, the PSC has the same problems when it comes to clinal
> variation that the biological subspecies does. Where do you draw the
> line? My understanding of the Zink & McKittrick proposal is that a
> conscientious application of the "extra barbule on the 7th feather"
> criterion is that clinal variation demands recognition of an infinite
> number of full phylogenetic species. Clearly an impossibility.
>
> The last time we discussed this issue on BirdChat, Paul DeBenedictis wrote:
>
> > There are more ominous implications of these viewpoints as
> > well. The 2nd issue of the Proc. of the Nat. Acad. of Sci.
> > (USA) for 1995 has a paper comparing the complete
> > mitochondrial DNA sequences of the great apes with three human
> > populations. The tree below summarizes approximately the
> > diferences (percent of DNA changed) found as a genealogy.
> >
> > |---------------------- chimpanzee
> > --| (from other great apes)
> > | |----------- African human
> > |----------|
> > | |--------- Japanese human
> > |-|
> > |--------- Caucasian human
>
> I pointed out that this result would require recognition of three species
> of humans and asked the proponents of the PSC if this is really the
> direction they want to go.
>
> Thus far, my question remains unanswered.
>
> ----------
> Joe Morlan
> Albany, CA
> jmorlan at slip.net
>
>
>
>
>