[Taxacom] barcode of life: PS

Richard Pyle deepreef at bishopmuseum.org
Sun Jul 4 19:36:53 CDT 2010

I said: 
> > So, by anyone's metric, there are effectively no 
> > biological reproductive barriers between these 
> > two species [C. flavissima / C. vroliki ]

You said:
> Incorrect!

I think we differ in our meaning of the word "biological" in this case.
When I used it in the line above, I meant "intrinsic to the biology of the
organism".  I would wager a lot of money that I could take any two
individuals of the two speies from anywhere within their respective ranges,
and they would be just as likely to produce viable offspring as any two
individuals from an established hybrid zone.

Of course, we don't know for sure -- because as far as I know, nobody has
done the experiment.

But what we REALLY don't know, and likely will not know for a long time, is
whether the reason the bulk populations are so consistently different is the
result of some sort of selection pressure keeping them that way, or is a
result of dynamic propensity to disperse over appropriate time scales (i.e.,
the hybrid zones are so narrow only because they came into existence only
relatively recently).

> It is all about finding (describing) patterns in nature - 
> patterns which "really are out there" (and need not have been if things
were different)
I've never, ever claimed that there are no patterns in nature.  If there
were no patterns, there would be nothing for taxonomists to do.  My only
contention is that evolution does not consistently produce sets of organims
that fit nicely into boxes we like to call "species" (by any definition of a
"species", BSC or otherwise).  The argument is about the degree of
inconsistency (which, following your human-height example, essentially
translates into the shape of the bell-curve). 

As I said in my last post, my own view of the shape of the average
bell-curve between species has gradually become broader (=less distinct)
over the years, as I accumulate more observations of natural populations.


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