[Taxacom] The Reality (or not) of Species (again!)`

Jim Croft jim.croft at gmail.com
Sun Sep 14 05:48:05 CDT 2008


Curse you Pyle!  (again!)  After months of blessed abstinence from
this abominable topic, I felt that sight was returning...  but alas,
it is obviously not to be... :)

Actually, I do not find the 'are species real' question all that
interesting.  It is about as exciting as pondering if languages are
real.  Real or not, languages and species seem to work.  Examples from
plants, animals, and likely the other kingdoms as well, show that
species are demonstrably not always absolute and a certain amount of
'fuzziness' should be expected rather than a surprise.  What is
interesting is that like languages, species appear 'real enough' to
keep going and remain recognizable (for the most part) - and like
languages they seem to be able to change incrementally at the margins
to the extent that over time they can become unrecognizable to the old
order but still coherent and functional to the new.  That's pretty
damned cool.

Like language, life is not a continuum, has never at any time been a
continuum and will never will be a continuum, even if we accept the
premise of a single common origin (seems reasonable but, as always:
[citation needed]).  We are dealing with a temporal lineage, a chain
of reproductive events as you say, with bits dropping in and dropping
out, making species more remarkable for the things that aren't there
than for the things that are.   The spectrum analogy does not really
work all that well because spectra by definition are continuous.  With
species (and taxa in general?) we have the equivalent of the visible
light spectrum with 99.999...% of the potential colours not there or
removed, apparently by some non random historical mechanism.  Yep,
that's pretty damned cool.

Not sure that, as pretty as the graphic is, this sort of smoky fluid
dynamics is the appropriate model for species and speciation - I think
it overstates the 'turbulence' in the system.  Also the premises of
momentum and directional energy from high pressure to low pressure may
not have comfortable evolutionary equivalents - I guess evolutionary
inertia might be conceivable, especially with climate change, but is
it possible for species to get 'on a speciation roll' and just plough
through the environment?   Turbulence is not chaos and it can be
modeled, with difficulty; with species and speciation there seems to
be a bit more order and predictability in the system (more a laminar
flow?), more than a series of random eddies and patterns in clouds.

Conceptually separating the historical temporal continuity from the
apparent (obvious?) contemporary discontinuity is a good approach.

Is this characterization of alpha vs phylo perspectives of species an
example of an incipient speciation event in itself?   Similarities and
differences vs descent of the shared and derived?  Defined vs
discovered?  Fuzziness vs rectilinear?  The Little Endians of Lilliput
vs the Big Endians of Blefuscu?

 Whatever - it is still a damned egg...  :)   ...and it came *after*
the chicken...

"That is, species boundaries are *defined* by us (not "discovered" by
us), and as such, are not "real" entities in nature."  - I do not like
this sentence; however it is probably not something that can be dealt
with sober.   Species boundaries are *observed* by us (or *perceived*,
or at worst *imagined*).  They are then defined and if the
definition(s) hold(s) up it would be reasonable to conclude that the
species *were* there and we discovered them.  We *discovered the
definition* (or did we define the discovery?).   (I tell you, there is
no surer way to go blind than to contemplate the reality of
species...)

"Species are "real" only in the sense that at any given moment of
time, the derivitives of evolution (i.e., organisms) form a clumpy
pattern, rather
than smooth continuum."   We need to discuss this sentence too.  Not
"only" the word "only", but about whether it is the organisms, the
species or the character is the derivative of evolution.   And at what
point did the Tuatara cease being Sphenodon whatsitsface and become S.
punctatus?   200 million years ago?  50 million?  10?  1?  A
millenium?  A century?  last year?  Last week?   You can bet one thing
- if an ancient Tuatara met a modern one there would be a serious
difference of opinion about eggs...

As I type this I am looking at my pet agaves, aloes, cactus an
euphorbias on the window sill - even with this small extant slice of
life the lineages hint at characters dropping in and out independently
of each other playing variations on a theme - not unlike words
entering and leaving a language.   Yep, pretty damned cool species...
or moderately consistent character aggregations...  or whatever...

now, where did I put  that white cane from last time this topic came up?

jim

On Sun, Sep 14, 2008 at 11:58 AM, Richard Pyle
<deepreef at bishopmuseum.org> wrote:
>
> I've broken this out into another thread, so as not to distract from the
> other (very interesting) discussion started by Bob Mesibov.
>
> Although we've had this discussion many, many times on this list before, I
> have some new ideas about how to articulate my own perspective, so I will
> try again.
>
> As with so many things we argue about, a lot of the aspects of this argument
> boil down to perspectives and semantics.
>
> I think most of us will agree that, as far as we know, most/all life on
> Earth has a common origin.  Working on that premise, then all living things
> today are connected to each other by a *continuous* and *unbroken* chain of
> reproductive events.  Unless we regard all of Life on Earth as a single
> species (not very practical for purposes of communicating about
> biodiversity), then we must draw boundaries between species at points along
> this *unbroken* continuum of reproductive events.
>
> >From the perspective of someone who is primarily interested elucidating
> phylogenies (which, I presume are intended to be congruous with some sort of
> evolutionary history -- though after reading Bob's earlier post re-launching
> the tracking characters thread, I'm not so sure anymore) -- species are
> "real" entities because surrounding us in nature there are seemingly
> unambiguous "sets" of organisms that cluster very tightly together in their
> characteristics, and we do *NOT* see continuous spectra between these sets.
> For example, we cannot find in nature today a continuous spectrum of
> organisms representing intermediates between humans, chimpanzees, and
> orangutans (Please, John -- I imply no phylogenetic affinities here).  The
> "fuzziness" between species, from this perspective, can be thought of
> primarily as a short-live phenomenon that happens only during periods of
> speciation (which are assumed to be very short, relative to periods between
> speciation events). In the example given, this "fuzzy" period lasted only
> during the time that the shared ancestor between humans and chimps (or
> between humans and orangs, or between orangs and chimps) was diverging into
> distinct species, and thereafter the three lineages can be thought of as
> "real" units of nature. From this perspective, it's quite appropriate to
> think of species as "real", which can be authentically represented by nodes
> at the tips of cladograms.
>
> The perspective of someone who operates in the world of alpha taxonomy is
> quite different.  From this perspective, the "non-reality" of species is not
> about comparing humans to chimps (or to orangs, or whales, or palm trees),
> it's about making decisions that seem utterly arbitrary.  People in this
> world are constantly operating in the realm of the "fuzzy" -- dealing with
> boundary effects between "putative" species.  They don't spend their time
> thinking about whether we should treat humans as a different species from
> chimps (...or orangs, or whales, or palm trees....).  They worry about
> things like "how many species of orangutans are there?"  I'm not a primate
> taxonomist, but as I understand it, until recently there was only a single
> species, with two recognized subspecies (one on Borneo, the other on
> Sumatra).  Now (I guess) those are recognized as full species, but some
> maintain that the Bornean species can be further divided into three
> subspecies.  Are there two species of orang? Four? One?  The notion that
> nature has the "correct" answer to this question, and that it's our job as
> taxonomists to continue studying the situation until we "discover" the
> "correct" answer, seems utterly naïve from this perspective.  Rather, from
> this perspective the "correct" answer is the one that best facilitates
> communication among humans.  That is, species boundaries are *defined* by us
> (not "discovered" by us), and as such, are not "real" entities in nature.
> Species are "real" only in the sense that at any given moment of time, the
> derivitives of evolution (i.e., organisms) form a clumpy pattern, rather
> than smooth continuum.  But when you look at it across time, the pattern is
> extremely smooth -- down to the resolution of a single generation against a
> background of billions of years.
>
> So which perspective is correct?  The obvious answer is "both" (or
> "neither", depending on whether you're the glass-half-full type, or the
> glass-half-empty type).  I know what perspective I have, and it reflects the
> nature of the world I live in, and the questions that interest me.
>
> As I tried to express in my previous post, it boils down to the question of
> what proportion of all evolutionary history is characterized by the "fuzzy"
> regions of speciation.  I already said that the "species are real"
> perspective generally assumes that the "fuzzy" zones are proportionally
> small on the grand scale of things.  [The only way you can eliminate the
> "fuzziness" altogether is to maintain that every single speciation event
> begins with an individual offspring that is not conspecific with its
> parent(s).]  But when you talk to people who operate from the other
> perspective, you find that many of them see the "fuzziness" as the dominant
> mode.  In my world, I see plenty of examples where the fuzziness of one
> speciation event has not yet attenuated while another apparent speciation
> event is already beginning.  In such cases, the entire pattern is fuzzy.
> And I can say that about a group of vertebrates -- which are typically MUCH
> "cleaner" in terms of having what we might perceive as "real" species than
> many/most other groups (e.g., plants).
>
> Sorry, Curtis -- I stand by my assertion that the image of the billowing
> smoke is a MUCH closer representation of the "reality" of the contunuum of
> life through the ages than the stick-figure cladograms we see so often.
> Sure, in the broadest/crudest sense, the stick-figures can be characterized
> as "representations of reality". But to those of us coming from the other
> perspective, such a notion is patently, laughably, absurd. Don't get me
> wrong -- cladograms are a GREAT tool for communication, in the same way that
> taxonomic nomenclature is a great tool for communication.  And they're a
> very convenient and intuitive short-hand method for representing hypotheses
> about gross historical patterns of descent.  But the danger, as others have
> already pointed out, is in allowing oneself to believe these stick figures
> represent "reality".
>
> Aloha,
> Rich
>
>
>
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-- 
_________________
Jim Croft
jim.croft at gmail.com

"Words, as is well known, are the great foes of reality."
- Joseph Conrad, author (1857-1924)




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