Evolution: time for some change?

Hmm. I thought that there'd be some objection to that idea. Is there actually any research on the correlation between sudden (ish) environmental change and mutation rates?
 
Sppokz, I think you're sniffing something other than blood if you think epigenetics provides the potential for passing on acquired traits. Particularly in most organisms which separate their reproductive cells and somatic cells very early. All of the cool epigenetic regulation of chromatin can't be involved, which makes it very hard to imagine any meaningfull passing of acquired characters ...

Canute - nothing I know about or I would have mentioned ... maybe paulsamuel knows something?
 
sci

quite possible!:)

blind cave fish

the mexican tetra fish lives in both caves/underground pools and streams/ponds. the former are blind and without pigmentation. eye development starts the usual way..rudimentary lens and optic cup. within 24 hrs however the cells die, cornea/iris does not develop. eyeball sinks and is covered by skin.

now it is known that shit atrophies without use. how is tho that the tetra passes on this degradation to its offspring.

dont plants do this kinda stuff all the time? if they do, how and why are we so special?

(pdf link p15)

there is more...butterfly wing morphology(p17) and geomyoid rodents (p19)

thoughts on this? on evo devo as a whole?
thanks
 
sniff sniff

Originally posted by scilosopher
Most epigenetics says nothing about acquired characters being passed on.
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most? what epigenetics says stuff about acquired characteristics?
 
gee
i decided to skim a bit and....Alternatively, there is the hypothesis that denies that these charactersitics have to evolve gradually from which derives the 'hopeful monster' theory and which is addressed by some 'evo-devo' researchers. (dr paul)
 
Originally posted by spookz
gee
i decided to skim a bit and....Alternatively, there is the hypothesis that denies that these charactersitics have to evolve gradually from which derives the 'hopeful monster' theory and which is addressed by some 'evo-devo' researchers. (dr paul)
Click to expand...

That not what I said, my answer does not conflict with that statement. Again epigenetics only deals with genes that control the function of other genes, epigenetics does not go against Darwinism.
 
:confused: the quote was attributed to paulsamuel.

epigenetics does not go against Darwinism.

why are some making a big stink about it? there is no controversy?

edit: just ignore posts. i respect you guys too much to screw this thread up:)
 
Honestly yes there is no controversy, scientist are just very excited about epigenetics because of new break-throughs in understanding it. Some things in epigenetic goes against the central dogma (like RNA only genes) a major revolution in thought. but epigenetic still obey the laws of heredity.
 
Re: Re: reply

Originally posted by copper
I don't disagree. But you can't say that post-reproductive organsims are as important to the population as those that can reproduce. Your example didn't really address this. I can't think of an example where a non- or post-reproductive organism is as important to the evolution of the population as one that can pass on its genes.
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Man is the only exception. All important things for mankind (except children) man create in post-reproductive period.
 
While the idea of epigenetic inhereitance might be dusty what is understood about it is quite new and cutting edge. Chromatin, imprinting (and it's importance in reproductive cloning), and the like are very interesting active areas of research. Indeed there may be the potential for epigenetic inheritance for all we know on germ plasm and the epigenetic state of certain genes. This could allow fast regulatory change in early developmental programs.

(spookz - I wouldn't claim all since I'm not completely on top of the field. I think there may be some examples from Susan Lindquist with yeast PSI that switching between prion states is favoured during cellular stress (due to titration of chaperones), which then is passed to progeny. I guess that counts as an acquired character, though it does exist in a latent form in the DNA.)
 
very nice sci. excellent attitude. a pox on the other retards

A fascinating example of epigenetic inheritance is available if one looks to the reptile world. While the sex of human offspring is determined genetically, in turtles two mechanisms exist: both a genetic mechanism and an epigenetic mechanism. Turtles are sex-typed at the time of fertilization but can have their sex reversed if the temperature during a specific phase of their development is appropriate to induce the change. Specifically, high temperatures are feminizing and lower temperatures are masculinizing. The temperature of a nest is often dictated by the mother's choice of nesting sites (Sura, 1995)

While the existence of phenotypic plasticity based on epigenetic inheritance does not necessarily point up the inheritance of the manifested phenotype there is a possibility that all people are vested with a wide range of phenotypic possibilities. If this turns out to be the case then one's mother (and quite possibly father) are capable of effecting a child's phenotype based on their biochemical states at the time of conception and based on the mother's biochemical state throughout the pregnancy. (LaMarck’s Redemption: New Evidence of Acquired Characters through Epigenetic Mechanisms)

*now with a little help from my yogi, i plan to bring a horned little devil into the world. ta y'all

edit: fixed refs
 
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It's very strange being a layman sometimes. I would have thought that this was perfectly obviously the case. I'm surprised to find you have to argue for it.
 
Originally posted by scilosopher
While the idea of epigenetic inhereitance might be dusty what is understood about it is quite new and cutting edge.
Click to expand...

maybe it is new and cutting edge in your field, but not in mine.
 
Originally posted by 2inquisitive
paulsamuel, I am not very informed about evolutionary theories, but
what is your take on "Beak of the Finch," the book that won the
1995 Pulitzer Prize by Jonathan Weiner? I have not read the book,
but saw a documentary on TV about Rosemary and Peter Grant's
work a few years ago. I'm sure you are aware of their study of the
quickly changing beak sizes of Darwin's finches to reflect the changing
food supply. Does that represent evolution and natural selection
or something else?
http://www.2think.org/tbotf.shtml
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Beak of the Finch is an excellent book. The Grant's work on the Galapagos finches is less a study than a life-long work. I'm not sure I would use the term 'quickly' for the changing beak sizes, but there were measurable differences between generations in beak size, within a population, before and after a drought. There is no question that these differences are the result of evolution by natural selection.
 
Originally posted by scilosopher
canute, I don't think anyone considers Darwin an expert on mutation. He was pretty much in the dark as to the basis for the generation of diversity ...

paulsamuel, what do you think about the CH Waddington hypothesis about selection for sets of alleles that alter biological function. The current incarnation of the idea is demonstrated in the Rutherford and Lindquist paper on hsp90:

http://www.ncbi.nlm.nih.gov/entrez/...ve&db=PubMed&list_uids=12101404&dopt=Abstract

The mechanism they suggest involves both cryptic variation and the possibility for selecting sets of alleles rather than single alleles. The basic idea is that hsp90 a chaperone (meaning it helps avoid misfolded proteins) masks certain allelic variants that bias a pathway towards a different behaviour. If you have multiple variants that encourage this behavior hsp90 can no longer mask the effect (possibly because the alleles are in a protein complex and mutually stabilize eachother). Therefore a population can harbor many mutations that alone have no effect and through sex rapidly generate the set that gives the improved phenotype.

I guess as a molecular biologist I feel uncomfortable speaking about things so abstractly that one looses site of mechanism and such ...
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I'm not familiar with the work, but I will follow up. It's interesting to see these heat-shock proteins popping up in all kinds of evolutionary studies. I worked on MHC genes for my dissertation and there could be analogous evolutionary forces at work. Since the breadth of evolutionary responses to environmental changes increase with the amount of variation present, this is probably important work (forgive my understatement).

Darwin's knowledge of mutation is less important than his recognition that variation was essential to his theory. The three tenets being 1) charactersitics that are heritable, 2) populational variation in these characteristics, and 3) selection among individuals based on the sum of the characterisitics. I think it is often overlooked that it is individuals that are the target of selection (i.e. the sum of the individual's characters, the phenotype), not individual characters, per se.
 
Originally posted by scilosopher
Fair enough. That more mutations happen under stressfull conditions (ie. when things aren't working out so well), is not that diffidult to imagine as a simple reduction in available energy (as during hunger) could clearly encourage mutation as mutation repair requires energy.

However I do not read any of the nuances you put forward into the passage above. Still you've given rise to the first mechanistic hypothesis as to why mutation may be higher at certain times and it has a natural correlation to when you'd want them. Though in multicellular organisms it isn't clear the timing would work out right (hungry mom has baby with more mutations than normal sounds like it would cause problems as much as evolution).
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I do recall a study in bacteria where replication repair mechanisms are detered or blocked under induced stress conditions, if I'm not mistaken. Also, isn't there some evidence of directed mutation in ADh genes in molluscs, IIRC?
 
Re: sci

Originally posted by spookz
quite possible!:)

blind cave fish

the mexican tetra fish lives in both caves/underground pools and streams/ponds. the former are blind and without pigmentation. eye development starts the usual way..rudimentary lens and optic cup. within 24 hrs however the cells die, cornea/iris does not develop. eyeball sinks and is covered by skin.

now it is known that shit atrophies without use. how is tho that the tetra passes on this degradation to its offspring.

dont plants do this kinda stuff all the time? if they do, how and why are we so special?

(pdf link p15)

there is more...butterfly wing morphology(p17) and geomyoid rodents (p19)

thoughts on this? on evo devo as a whole?
thanks
Click to expand...
this is not an example of Lamarkian inheritence. There are 2 mechanisms that can explain the loss of characters under these circumstances, selection and drift. Please don't misunderstand me. I am not dismissing the inheritence of acquired characterisitics (I'm discontinuing my use of the term 'Lamarkism' because that is not what he was about). Steele has presented some supporting evidence that is controversial, but still scientific in the Kuhnian sense (see Lamark's Signature, 1998 Perseus Books).
 
Originally posted by scilosopher

paulsamuel, what do you think about the CH Waddington hypothesis about selection for sets of alleles that alter biological function. The current incarnation of the idea is demonstrated in the Rutherford and Lindquist paper on hsp90:

http://www.ncbi.nlm.nih.gov/entrez/...ve&db=PubMed&list_uids=12101404&dopt=Abstract
Click to expand...
I don't get the referenced paper from this link, if you could give me the real ref. i.e. journal, date, vol., pg., i'd appreciate it. TIA

never mind, got it on my own on pubmed search of Lindquist and Rutherford, here's the ref FYI
Rutherford SL, Lindquist S.
Hsp90 as a capacitor for morphological evolution.
Nature. 1998 Nov 26;396(6709):336-42.

I'm fortunate enough to be at a university that has Nature on-line and would be happy to forward a pdf to anyone willing to supply an email address.
 
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