Evolution: time for some change?

Discussion in 'Biology & Genetics' started by spuriousmonkey, Oct 6, 2003.

  1. spookz Banned Banned

    Messages:
    6,390
    bah
    even though i know next to nothing about this stuff, i sniff blood!

    Please Register or Log in to view the hidden image!

     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. Canute Registered Senior Member

    Messages:
    1,923
    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?
     
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. scilosopher Registered Senior Member

    Messages:
    435
    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?
     
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. spookz Banned Banned

    Messages:
    6,390
    sci

    quite possible!

    Please Register or Log in to view the hidden image!



    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
     
  8. spookz Banned Banned

    Messages:
    6,390
    sniff sniff

    most? what epigenetics says stuff about acquired characteristics?
     
  9. spookz Banned Banned

    Messages:
    6,390
    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)
     
  10. ElectricFetus Sanity going, going, gone Valued Senior Member

    Messages:
    18,206
    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.
     
  11. spookz Banned Banned

    Messages:
    6,390

    Please Register or Log in to view the hidden image!

    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

    Please Register or Log in to view the hidden image!

     
  12. ElectricFetus Sanity going, going, gone Valued Senior Member

    Messages:
    18,206
    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.
     
  13. Gagarin Registered Member

    Messages:
    29
    Re: Re: reply

    Man is the only exception. All important things for mankind (except children) man create in post-reproductive period.
     
  14. spuriousmonkey Banned Banned

    Messages:
    24,066
    since when is epigenetics a new idea?

    it was a reaction to preformatism. It's a dusty part of history.
     
  15. scilosopher Registered Senior Member

    Messages:
    435
    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.)
     
  16. spookz Banned Banned

    Messages:
    6,390
    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
     
    Last edited: Dec 11, 2003
  17. Canute Registered Senior Member

    Messages:
    1,923
    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.
     
  18. spuriousmonkey Banned Banned

    Messages:
    24,066
    maybe it is new and cutting edge in your field, but not in mine.
     
  19. paulsamuel Registered Senior Member

    Messages:
    882
    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.
     
  20. paulsamuel Registered Senior Member

    Messages:
    882
    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.
     
  21. paulsamuel Registered Senior Member

    Messages:
    882
    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?
     
  22. paulsamuel Registered Senior Member

    Messages:
    882
    Re: sci

    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).
     
  23. paulsamuel Registered Senior Member

    Messages:
    882
    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.
     

Share This Page