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 Posted: Wed Jul 16, 2008 8:32 pm Post subject: Re: Rewriting Darwin: The new non-genetic inheritance |
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On Jul 14, 2:05 am, Tim Tyler <seemy...@googlemail.com> wrote:
[quote]Rewriting Darwin: The new non-genetic inheritance - From New Scientist
http://groups.google.com/group/soc.culture.romanian/msg/ccf8322969990515
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[/quote]
On Jyly 12 Confutius wrote:
[quote]While examples of this "transgenerational epigenetic inheritance" >are only just emerging in mammals, there is long-standing and >widespread evidence for it in plants and fungi.
[/quote]
While examples of this "transgenerational epigenetic inheritance" are
only just
emerging in mammals, there is long-standing and widespread evidence
for it in plants and fungi.
“Transgenerational epigenetic inheritance” and appearance in the
offspring of new heritable characters that parents did not possess
(without changes in genes) is also long-standing and widespread in the
animal Kingdom, both in unicellulars (remember experiments on cortical
inheritance in Paramecium by Sonneborn and coll. in early 60es of the
20th century) and metazoans.
Typical examples of “transgenerational epigenetic inheritance” from
invertebrates are:
Phase transition in locusts.
Acquisition of resistance to cyanobacteria by the crustacean Daphnia
magna, where investigators believe that “experienced mothers transfer
information about their environment to their offspring” (LaMontagne
and McCauley, 2001).
All female, parthenogenetically reproducing Daphnia magna, in response
to environmental stress, produces both male and females, thus starting
sexual reproduction.
In response to the longer photoperiod and higher temperature Aphis
fabae larvae do not develop wings and adaptively switch from oviparous
to viviparous mode of reproduction, etc.
Among described cases of “transgenerational epigenetic inheritance” in
vertebrates are:
Sudden decrease in F1 of the number of armour plates and in general
body morphology of the marine stickleback fish Gasterosteus aculeatus,
when transferred to freshwater ponds (Kristjansson, 2005).
Sudden transgenerational decrease in the size of the offspring of
female zebra finches under conditions of environmental stress, etc.
All the cases of transgenerational epigenetic inheritance described so
far involve no changes in genes. Besides, there is no hint that
epigenetic processes of the kind of gene imprinting and chromosome
remodeling may be involved in the emergence of new characters in cases
of transgenerational developmental placticity. Since the new
characters imply investment of new information the question arises:
Where the epigenetic information for the evolution of the new
characters come from?
The source of the epigenetic information for the appearance of new
characters in best studied cases of transgenerational inheritance is
the central nervous system (see chapter 12 of Epigenetic Principles of
Evolution (pp. 315-339) in http://www.epigeneticscomesofage.com (*in
case the link doesn>t work, please copy/paste
epigeneticscomesofage.com into your browser). |
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