largest organism

Ian A. York iayork at panix.com
Thu Feb 27 20:45:22 EST 1997


In article <33119033.2F2D at wfu.edu>,  <taguebw at wfu.edu> wrote:
>
>No, probably not blue whale. But a fungus. If I remember, it is both 
>bigger in length and larger in mass. I can't point you to any ref's 

This is completely off-topic, but I since I saved my post on this from
another newsgroup (a long and rather dull story as to why it was on-topic
there) I'll repost it here.  

Subject: Last fungus stuff
Date: Sat, 3 Feb 1996 11:09:54 -0500 (EST)

OK, you're probably sick and tired of this by now, but here's the final
installment.  Turns out that I wasn't as far afield as I thought -
although the original article didn't discuss the implications and
definitions of individuality, an accompanying editorial comment did.  But
rather than quote that directly, here's what Stephen Jay Gould had to say
about it.  This is from his essay A Humungus Fungus Among Us, on p. 335 of
_Dinosaur in a Haystack (Random House, New York, 1995; ISBN
0-517-70393-9); the essay originally appeared in Natural History Magazine.
This is a very superficial overview of the essay, of course - buy the book
now! 


     (The first three pages or so describe the Nature article and explain
the work.)
     But this elegant demonstration that the Michigan mat formed from 
a single source only opens the more interesting and portentous issue of 
defining individuality - *the* central question, as we shall see, for 
applying Darwinian theory to nature.  The Michigan Aillaria mat grew 
vegetatively from a single source, but does such a thirty-acre spread 
qualify as an individual under our usual vernacular definitions?  Clive 
Brasier addressed this question in a commentary ... in the April 2 issue 
of Nature [1992]:

          The suggestion of Smith et al. that [the Michigan mat] deserves 
     recognition as one of the largest living organisms, rivalling the
     blue whale or the giant redwood, deserves closer scrutiny.  The blue 
     whale and redwood exhibit relatively determinate growth within a
     defined boundary, whereas fungal mycelia do not. 

     In other words ...Pieces [of the fungus] may break off and become
physically separated from the main mass; but a whale's flipper, if broken
off, is dead meat, not a miniwhale. 

     So, although [the Michigan mat's] reputation as a champion genotype 
     may yet be secure, its staus as a champion organism depends on one's
     interpretation of the rules. 

     [Gould discusses some definitions of individuality]
     Botanists, more often than zoologists, encounter this problem of 
apparent parts that look like individuals {though a colony of coral 
anmals raises exactly the same issue).  Botanists have therefore devised 
a special terminology to treat these ambiguous cases of parts that look 
like entire organisms of vernacular usage, but act as organs of a larger 
totality by the genetic definition.  ...
     The vernacular and genetic definitions are driven even further apart 
when we recognize that even the chief criterion of connectedness can fail 
when we advocate the genetic criterion.  [Gould discusses parthogenic 
aphids, citing a 1977 article by Dan Janzen entitled "What are 
dandelions and aphids?"  American Naturalist 111:586-589, which notes 
that all the 'offspring' of the aphids in the parthogenic period are 
genticall identical to the 'parent' and therefore complicate the 
'individual' definition.]
    ...Why, Janzen argues, should we not label the aphid bodies as parts, 
and the entire clone as a sinle E1, or "evolutionary individual"?  This 
redefinition yields some startling consequences ...
    [Gould takes a couple of pages to discuss some of the implications, 
and some of the other possible approaches.]
    ...Thus, individuality extends beyond Armillaria mats and aphid 
clones to encompass different levels of biological organization - so 
different that we have usually called them parts or collectivities under 
the parochial assumption that only organisms can be units of seleection.  
... All these levels produce legitimate Darwinian individuals - and this 
hierarchical definition gives us the large, inclusive, and proper 
biological meaning of the term _individual_.  
     ...Nature is not an intrinsic harmony of clearly defined units.  
Nature exists in multiple levels, interacting with fuzziness at the ir 
borders.  We cannot even formulate an unambiguous definition of 
"individual" at the single level of organic bodies - as Armillaria mats 
and aphid clones clearly demonstrate....
-- 
      Ian York   (iayork at panix.com)  <http://www.panix.com/~iayork/>
      "-but as he was a York, I am rather inclined to suppose him a
       very respectable Man." -Jane Austen, The History of England



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