BSC - sibling species - PSC

John Grehan jgrehan at SCIENCEBUFF.ORG
Tue Nov 11 13:05:02 CST 2003

I agree with Barry's very succinct observation and liked his wry humor. And
what is a hybrid if not something that eludes being named?

I will add (without presuming that Barry would necessarily agree) that BSC
and PSC both appear to be essentialist in that they define species by
spatially unrestricted criteria (such as reproductive viability, a
designated character, or in the case of the mate recognition concept, the
ability to recognize the essential 'self' of a species). I wonder if
molecular approaches can ever solve anything that is already rendered
inherently insoluble.

Another (Better?) approach is to view species as spatiotemorally
diagnosable entities (i.e. a species boundary can be delineated with
respect to a particular place and time, but not all places and times
without invoking an essence). The trouble is that I have held this
view  for nearly 15 years and perhaps my views are  fossilized in a stratum
out of place and time in this post-modern world (although perhaps some
'fossils' are better than others).

John Grehan

At 09:38 AM 11/11/2003 -0800, Barry Roth wrote:
>If the essays in Q. D. Wheeler & R. Meier (eds.), Species Concepts and
>Phylogenetic Theory:  a Debate.  New York:  Columbia University Press,
>2000, are any indication, then "never the twain shall meet."  Ernst Mayr's
>essay in that volume demonsted that his position on the BSC was virtually
>the same in 2000 as it was on its publication in 1940 -- a tribute either
>to the concept's robustness or the author's intransigence; maybe a bit of
>both.  The fundamental difference in approach -- the BSC states in effect
>"two [taxa] are different because they are species" while the PSC states
>"they are species because they are different" -- would make your proposal
>for a spittle of one mixed with a bit of the other a peculiar hybrid, I
>Matt Buys <BuysMH at PUKNET.PUK.AC.ZA> wrote:
>Hi all
>Two questions:
>1. One of Ernst Mayr's objections to the phylogenetic species concept
>is its failure to recognise so-called sibling species which by
>definition look identical externally. In the light of advances in the
>molecular field, is there published research on whether two sibling
>species that look identical externally can be grouped into two taxa
>based on molecular evidence?
>2. The BSC has to do with the ability to reproduce. The phylogenetic
>species concept (PSC) is based on the possession of unique characters.
>All individuals resulting from sexual reproduction are however unique
>(at least at the molecular level). So as I see it, to be a species, you
>have to possess characters that are unique (enter the PSC) to a
>population or group of populations, implying some form of gene flow
>(enter the BSC), but not unique to an individual. So, can I submit to a
>species concept for sexually reproducing organisms consisting of dual
>elements, viz. a spittle of BSC mixed with a bit of PSC?
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Dr. John Grehan
Director of Science and Collections
Buffalo Museum of Science
1020 Humboldt Parkway
Buffalo, New York 14211-1293
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