Eutely
Jared
multicellular organisms were eutelic once, or did it develop later?
Lorentz
> What's the word for non-eutelic, and is it thought that all
> multicellular organisms were eutelic once, or did it develop later?
I found an article where the authors use the word �noneutelic�.
Here is a link:
http://www.pnas.org/content/98/10/5699.full
I think that �eutelic� and �noneutelic� are antonyms.
The word eutelic refers to the variability in cell number of an
organism in a species. I suspect that the variability of cell number
is itself a continuous variable. Most animals (not plants) grow to a
certain maximum size and stop. Some animals keep increasing cell
number with age without limit. There is no taxon for �eutelic�
animals.
My conjecture is that the earliest multicellular organisms were not
eutelic. The reason that I think so is that multicellular organisms
most probably evolved from colonial organisms. Multicellular colonies
are not eutelic. Any number of cells can belong to this colony. The
regulation of cell number, and the infertility of some cells in the
colony, had to evolve in small steps. Therefore, eutely has to be an
extreme specialization.
First you would have colonies where the number of cells varied.
Then, you would have multicellular organism with a division between
germline cells and somatic cells. As the final step, strict regulation
of cell number.
If you grow a colony of bacteria on a Petri dish, the colony
can assume all sorts of pleasing patterns. However, the number of
cells is not fixed. Most plants do not have even an upper limit to the
number of cells. Our human cells have a limit on division regulated by
the tip of the chromosomea. However, the number is not fixed in human
beings. The number still varies. Only a few multicellular organisms
have strict eutelly.
>From Wikipedia
Eutelic organisms have a fixed number of cells when they reach
maturity, the exact number being constant for any one species.
Development proceeds by cell division until maturity; further growth
occurs via cell enlargement only.
Most eutelic organisms are microscopic: examples include the rotifers,
nematodes, tardigrades and dicyemida.
List of �utelic� animals:
http://www.stanford.edu/~ashishg/robert-williamson-eutelic.html