[Taxacom] Robust argument

Richard Zander Richard.Zander at mobot.org
Tue Jun 30 09:25:29 CDT 2009


There is also fellow traveler information that accompanies the genome.
Think of the environment to which a particular organism is adapted as an
extra chromosome floating outside the genome but affecting major aspects
of the organism's existence. Stabilizing selection not only keeps a
species in relative stasis morphologically for major periods of time,
but also necessarily keeps the environment the same. A host, for
instance, is a kind of environment for a parasite; a pond (through
geological time) is much the same for a water bug. 

Given this partnership of environment and genome, one should not look
only to the genome for all possible information on evolution through
time of a species.

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Richard H. Zander 
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Missouri Botanical Garden
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-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of
Don.Colless at csiro.au
Sent: Tuesday, June 30, 2009 12:00 AM
To: mesibov at southcom.com.au
Cc: taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] Robust argument

Willi Hennig's term "holomorph" could be extended to include genomic
characters; or perhaps we could use "hologenome".

Donald H. Colless
CSIRO Div of Entomology
GPO Box 1700
Canberra 2601
don.colless at csiro.au
tuz li munz est miens envirun

________________________________________
From: taxacom-bounces at mailman.nhm.ku.edu
[taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Bob Mesibov
[mesibov at southcom.com.au]
Sent: 28 June 2009 15:25
To: michael.heads at yahoo.com
Cc: taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] Robust argument

I couldn't agree more that the word 'genome' needs relaxing so that it
isn't restricted to genes and gene inheritance, or alternatively that we
use a word with a broader meaning, so that inheritance isn't restricted
to genetic inheritance. There probably is such a word in the biological
literature already. Anyone know it?

IMHO this is what Richard Pyle and others have done on TAXACOM a number
of times, i.e. argued that genes are the only things passed down the
evolutionary tree, therefore everything we can infer about organismal
history is somehow inherent in the genome, and if we could only read the
genome properly we'd have the whole evolutionary story.

All three clauses are untrue. This kind of reasoning had a chemical
analogy in the 19th and early 20th century: organisms are only made of
atoms and molecules, there's no vital force; therefore everything we can
infer about how organisms work is inherent in atoms and molecules, and
if we could only completely understand the chemistry we'd have the whole
organismal story. Anyone still think that way?

Genes are not the only things passed down the evolutionary tree. Michael
Heads and I have mentioned location. You can look as deep as you like
into the genome, but you won't find the 'endemicity address' that
locates a plant species on top of some mountain on Madagascar. That
address is inherited. It's passed on to the next generation of seedlings
by the current generation of seeding plants. Fuzziness in location as an
inherited character is equivalent to variation in any gene-inherited
character.

There are other non-genetic ways in which evolution is directed. Many
are contained with the word 'co-evolution' - of parasites and their
hosts, and of other tightly associated taxa. Think of a beetle which
feeds on a particular plant, concentrates a particular metabolite from
that plant, stores it in a special structure, then uses the material to
defend its eggs against egg predators. You can find genetic traces of
this separately in the beetle genome, the host plant genome and the
predator genome. You think you can reconstruct this bit of evolutionary
history from those genetic traces?




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