[Taxacom] barcode of life

Richard Pyle deepreef at bishopmuseum.org
Sun Jul 4 19:19:27 CDT 2010


> So in a sense I am in agreement with Rich that the question 
> CAN become: Would it best serve the communicative needs of 
> biologists to regard them as the same species?
> But somehow I see it as a consequence of the application 
> of the BSC to certain cases that fall into the "fuzzy zone"

This is what I've always seen as the crux of the issue, going back as long
as I've been vociferous on this whole real vs. defined species debate.  I
think everyone agrees that examples exist to illustrate the extremes.  The
question really is: where is the boundary between "normal" and "extreme"?

If most species fall into the "punctuated-equilibrium" sort of mode, then
we'd expect the "fuzzy zone" to be the exception, rather than the rule.  If
I look at a checklist of fishes from some region, or a monograph of some
group I'm familiar with, it's easy to see this as the case (i.e., to get the
impression that the fuzzy zones are the exception, rather than the rule).
But as I increase the time I spend observing populations in the field, and
as I increase the number of places that I go to and observe those
populations, I start to see more and more "fuzzy" examples.  In some
families more than others, to be sure.  But the point is, the more carefully
I look at what's actually happening on the reefs, the more ratio of "fuzzy"
vs non-fuzzy shifts in the direction of the former.  

I can't say that the fuzzy examples necessarily outnumber the non-fuzzy
examples; but they certainly represent a non-trivial component.  And the
trend continues to favor the fuzzy examples as my time and field experience
(~25 years; ~40 different regions in the tropical Indo-Pacific, depending on
what resolution of "region") increase.

But my expertise is limited to coral-reef fishes.  How does that compare to
marine invertebrates? Or terrestrial invertebrates? Plants? Bacteria? Fungi?
Protozoa? Etc., etc.  I don't know.
 
> A potential problem with Rich's view (or his way of expressing it), 
> is that asking the question, would it best serve the communicative needs
of 
> biologists to regard them as the same species?, risks giving people a
mandate 
> to give mere populations species status just to afford them legal
protection 
> status (as mentioned in Jim Croft's last post, which now has some
relevance!) 

"Best communicative needs of biologists" covers the full spectrum of
cummunicative needs.  Legal protection represents only a tiny fraction of
the overall collective needs, so only has (*should* only have) a
proportionally small influence over decisions about species boundaries.

> It implies total subjectivity of species boundaries, 

Not total subjectivity.  Just not total objectivity either (as some wishful
thinkers would like it to be).

> and is vague about 
> who exactly the "biologists" are, and what their "communicative needs"
are? 
> Do we include conservation biologists? What are their "communicative
needs"? 
> Do we include molecular biologists?

Of course these are vague, and therein lies a big part of the problem!  A
single 250-year-old system (first established by a de-facto creationist)
used to suit the needs of a WIDE variety of people. The extraordinary thing
is how often biologists actually tend to agree on where the lines should be
drawn for species!  Norms have shifted over time, of course -- but in the
vast majority of the nearly 2 million named species, there is very little
contention.  It's amazing that, even though most species are named according
to the "a species is what a community of taxonomists says it is" principle,
the ratio of agreement to disagreement is still very high.  That, by itself,
almost leads one to conclude that species really do exist in nature, outside
of human definitions! (Almost.... :-)  )

> At least my BSC approach gives us something to hit back and say 
> "no way is that population a distinct species to that one!". 
> It has no consistent morphological or genetic differences that 
> would suggest high levels of reproductive isolation!

What you describe is not just your approach; in fact, it has been the
approach of the majority of taxonomists since Darwin (certainly since Myer).
Myself included.  I think the only difference between you and I on this is
that I see the BSC as the most powerful metric for deciding whether it meets
the best communicative needs of biologists to classify two populations as
the same species or different species.  If I read you correctly, you see it
as the only metric.

Aloha,
Rich






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