Re: Sociobacteriology

On Sat, 27 Oct 2007 18:43:26 -0700, *Hemidactylus*
<ecphoric@xxxxxxxxxxx> wrote:

On Oct 27, 9:20 pm, r norman <r_s_norman@xxxxxxxxxxxx> wrote:
On Sat, 27 Oct 2007 20:55:41 -0400, "Perplexed in Peoria"





<jimmene...@xxxxxxxxxxxxx> wrote:

"hersheyh" <hershe...@xxxxxxxxx> wrote:
On Oct 26, 11:54 pm, Mujin <umwin...@xxxxxxxxxxxxxxxxxxx> wrote:
"Perplexed in Peoria" <jimmene...@xxxxxxxxxxxxx> wrote:

[Mujin:] Is segregation of the germ line necessary?

Yes. Crucial. It is the thing that insures that the metazoan cell
has absolutely no interests (evolutionarily speaking) that are
divergent from those of the collective. Not so for human and
bacterial societies. They are built on the (relatively weak)
principle of reciprocity. But true multicellular organisms (animals,
anyways) are built on the (relatively strong) principle of one-for-all
(with all-for-one being dispensible).

I think this is probably the clearest and most succinct explanation for the
necessity of germ line segregation in metazoan organisms that I have seen.

Except, of course, that one must remember that eucaryotic "sex" (that
is, a cycle of meiosis to generate 'gametes' and fusion of 'gametes'
to regenerate a 'diploid' cell -- remembering that for some organisms,
the haploid state which is not 'temporary' but reproduces, even
producing organisms, mitotically) exists in non-multicellular
eucaryotes as well as many metazoans. That is, the requisite
requirement for germ line segregation in metazoans existed well
*before* multicellularity, either clonal or metazoan. And many
metazoans (most notably plants, but also some animals) have
secondarily reduced or eliminated reproduction via a "germ line" and
reproduce clonally either permanently (bdelloid rotifers) or
facultatively. That is, multicellularity is clearly separable from
any specific method of reproduction.

AFAIK, there are no truly multicellular haploid asexuals. You are
right to emphasize sex, rather than strictly germ-line segregation, as
an important factor. Sex typically means that an individual is not
particularly similar genetically to its sibsand hardly similar at all to
second cousins. Therefore, if a cell is capable of both sexual and
asexual reproduction, each individual in an asexual clone has every
genetic incentive to act altruistically toward clone-mates and to
compete against sexually produced cousins. This is true both for
metazoa and cellular slime molds. But in a bacterial colony or in
a stand of aspen, your clone-mates are also your competitors,
so there is no particular incentive for altruism. Only the usual
economic incentives for reciprocal cooperation - incentives which
are there whether you are related or not (and even conspecific or not).

[snip stuff about infectuous cancers]

In the case of metazoans,
differentiation is much more extreme, and thus cooperation is
enforced. In heterogenous bacterial communities, different species
sometimes perform different functions which permit the survival of
the whole community, and even in homogenous communities there are
examples of differentiation (such as the cyanobacteria I mentioned
earlier).

But, once again, this is the limited kind of cooperation that arises
from reciprocity rather than truly shared interests. It can
accomplish some collective virtuousity, but nothing like what a
multicellular organism can do.

Well, you must be emphasizing the *organism* part of the phrase. But,
as I mentioned, sometimes the word "organism" can be tricky. There
are multicellular entities that are temporary and not "organisms" in
the general anthropocentric meaning of the word. Nature is simply
stranger than you (or I) think.

It is indeed. But there are some additional criteria which should be
applied to restrict the word 'organism' beyond just being a collection
of smaller-scale living entities. I've mentioned shared genetic interests
and germ-line segregation. But there is also a time scale issue. Any
collective whose lifespan is less than that of its members doesn't qualify.
Nor, I think, does a collective which actively absorbs and recruits
outsiders during its lifespan. Ideally, an organism is a collective whose
members are related clonally, operating in an environment in which it
ecologically competes against organisms which are not clonally related.

Human societies don't qualify. Nor do many colonial organisms. But
ant and bee colonies come fairly close. I'm of two minds about stands
of aspen. The individual trees grow tall to compete for sunlight. But
in the interior of an aspen stand, those trees are competing against
clone-mates. Do they compete just because they are too stupid to
realize that they are competing against themselves? Or are they smarter
than we realize (Orgel's law).

Liverworts are multicellular haploid organisms that can reproduce
asexually as well as sexually. Some asexually reproducing lizards
are, I believe polyploid. I don't see where the ploidy plays into
asexual reproduction.

There are many asexually reproducing organisms whose components
outlive themselves. That is how vegetative reproduction or budding
occurs. You still readily recognize an individual Hydra, for example.
I think you get into serious trouble if you try to pin down your
definitions precisely. Biology has far too many weird cases.

I named myself for one of these weird cases. The species of gecko
known as *Hemidactylus garnoti* is asexually reproducing (ie-
parthenogenic). I used to keep some in captivity and yes without
mating they laid eggs. They aren't as easy to catch as anoles. They
lick their eyes and make funny squeaky noises.

I about fell over with laughter when I noticed a local commercial pet
store selling Cuban anoles and Cuban tree frogs for more than 5
dollars. They even had a warning about the nasty skin secretions of
the tree frogs. I can walk outside on any given warm summer day and
catch enough anoles to quit my day job. I have no idea why someone
would want a Cuban treefrog as a pet. They make better food items for
garter and ribbon snakes. I fed Cuban tree frogs to my ribbon snake
several times. It was a sight to behold, but not for the squeamish.
Cuban tree frogs make strange cat meow noises when the snake is
stretching its jaws over its body. But I would guess that a ravenous
Cuban tree frog would eat a smaller snake, so its fair.

I was wondered about that name; whether your fingers got cut off
halfway down or something. But I was too lazy to google it.
Otherwise I would just have assumed you were a car insurance salesman.

Feeding snakes is a serious problem for biology departments. There
are strict laws about the care and handling of vertebrate animals and
keeping mice and rats (or chickens and rabbits if your snakes are
large enough) to for use as live food is something that is difficult
to get approved by the Animal Care and Use Committee.


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Relevant Pages

  • Re: Sociobacteriology
    ... necessity of germ line segregation in metazoan organisms that I have seen. ... any specific method of reproduction. ... The individual trees grow tall to compete for sunlight. ... I fed Cuban tree frogs to my ribbon snake ...
    (talk.origins)
  • Re: Sociobacteriology
    ... necessity of germ line segregation in metazoan organisms that I have seen. ... any specific method of reproduction. ... there are no truly multicellular haploid asexuals. ... The individual trees grow tall to compete for sunlight. ...
    (talk.origins)
  • Re: Sociobacteriology
    ... necessity of germ line segregation in metazoan organisms that I have seen. ... any specific method of reproduction. ... asexual reproduction, each individual in an asexual clone has every ... The individual trees grow tall to compete for sunlight. ...
    (talk.origins)
  • Re: Sociobacteriology
    ... necessity of germ line segregation in metazoan organisms that I have seen. ... any specific method of reproduction. ... I fed Cuban tree frogs to my ribbon snake ... Feeding snakes is a serious problem for biology departments. ...
    (talk.origins)
  • Re: talk.origins faq Hitler claim part 3
    ... Organisms do not ... life uniformly and consistently has is reproduction. ... a designer and the purpose the designer had in mind for each design. ... about natural selection in these posts. ...
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