So new species can't arrise suddenly...

Discussion in 'Biology & Genetics' started by Unconcept, Mar 2, 2012.

  1. Unconcept Registered Senior Member

    New species can't arrise suddenly because the genetic variations occur slowly, but how come I hear biologists say that we have observed macro evolution?

    Also doesn't rapid evolution happen sometimes like the color or size of the beak of the birds changing over only one generation? Could someone explain and give me examples of this?
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  3. arfa brane call me arf Valued Senior Member

    It depends what you think "slowly" means.

    Some organisms are able to vary their genes rapidly. Bacteria do this when they develop resistance to antibiotics, or to any other environmental change. They do this quickly enough that we can observe it, hence: observable macro-evolution.
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  5. spidergoat monosyllabic dictionary Valued Senior Member

    It also depends on what you think "species" means.
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  7. Grumpy Curmudgeon of Lucidity Valued Senior Member


    Evolutionary changes can occur fairly rapidly, given high evolutionary pressure. It involves a lot of death, however. In addition, the genomes of higher animals may contain templates for changes that have already occurred in the past but were supplanted by later additions. These templates can be activated under stressful conditions. Puntuated Equilibrium is a theory that states that for long periods little change occurs because there is no evolutionary pressure to do so, but when conditions change and populations go through bottlenecks of low populations, low populations allow rapid changes over short(relatively)time periods, followed by the newly changed populations coming back to a new equilibrium with the new conditions. Of course, such conditions often lead to extinction as well, most of the species ever to exist are now extinct, but that opens up new niches for others to fill.

  8. origin It keeps getting funnier.... Valued Senior Member

    No. That would be a mutation, not evloution.
  9. wlminex Banned Banned

    Mutation is the primary mechanism by which evolution occurs . . . . constructive mutations survive . . . destructive (or de-constructive) mutations (generally) don't.
  10. James R Just this guy, you know? Staff Member


    Genetic variations potentially occur ever time a cell divides.

    What do you mean by "slowly"?

    Why would macroevolution not follow directly from microevolution?

    How do you distinguish the two?

    Sure. What colour eyes do you have? Are they the same as the eye colour of both your parents?

    It is not uncommon for both parents to have brown eyes and for their child to have blue eyes. That's a change in colour over only one generation, right there.
  11. Grumpy Curmudgeon of Lucidity Valued Senior Member


    Because we have.

    Define "macroevolution". It's a term rarely used by biologists. Assuming you mean an example of one species producing two, non-interfertile species, here you go...


    "The various Ensatina salamanders of the Pacific coast all descended from a common ancestral population. As the species spread southward from Oregon and Washington, subpopulations adapted to their local environments on either side of the San Joaquin Valley. From one population to the next, in a circular pattern, these salamanders are still able to interbreed successfully. However, where the circle closes -- in the black zone on the map in Southern California -- the salamanders no longer interbreed successfully. The variation within a single species has produced differences as large as those between two separate species."

    Examples we see of two lineages in the process of speciation are horse/donkey=mule(infertile), lion/tiger=liger(usually infertile), buffalo/cow=beefalo(still fertile, usually), dog/wolf(still interfertile, but my chihuahua is more likely to be a snack for a grey wolf than a mate). These are all various stages in speciation events covering thousands and hundreds of thousands of years. They are comparable to the various stages of the salamanders above but due to longer life and reproduction timelines evolution is usually much slower in large mammals.

    Evolution is a fact, it has been seen to occur throughout the history of life on Earth. Our picture and understanding of the reasons to explain that fact are only as good as the evidence we have(each fossil is a snapshot of that time in history), but we have enough of these snapshots to show the fact that evolution occurred, in many lineages enough to make a pretty good movie of what occurred and the more snapshots we find the better the quality of that movie. Theories explaining what occurred may change, but what doesn't change is the fact of evolution.

  12. Robittybob1 Banned Banned

    Interesting for the resistance to antibiotics may not be just a selection for the bacteria that have an enzyme that confers resistance.
    Has anyone shown that there is an improvement in the enzyme. Like do the bacteria increasingly get better at deactivating the antibiotic?
    Now that is what I would call evolution. :)
  13. Aqueous Id flat Earth skeptic Valued Senior Member

    It's crazier than that... they will immunize their buddies:
  14. matthew809 Registered Senior Member

    The bacteria does not create new DNA from thin air. The ability for these adaptions are already programmed into it's DNA. Much like a transformer (yes the toy) does not "evolve" every time it changes it's form to adapt to a given situation. Sometimes transformers may combine or trade parts with eachother. Again, this is an example of change, but not macro-evolution.

    I realize it's not a perfect analogy.

    Example: You can selectively breed a dog bigger and bigger each generation, but there is a limit to the size it can get. If macroevolution followed from microevolution, this limitation would not be the case.

    Here's how I distinguish microevolution from macroevolution:

    Microevolution describes change which can be accounted for by the original DNA code of the ancestor.

    Macroevolution describes change which can not be accounted for by the original DNA.

    Note: in order for macroevolution to be proven true, lineage must be established, and a complete understanding of the DNA of the entire lineage must be had.
  15. billvon Valued Senior Member

    Yes, it does. DNA randomly gets longer (and shorter) during reproduction.

    No, they're not. Bacteria are a good example. There is no way they could have possibly had the programming to fight modern synthetic antibiotics - but given enough time they can indeed evolve a resistance to it.

    No, there's not. It could become as big as a blue whale. Even bigger if it was advantageous to do so. Indeed, the blue whale's ancestor (pakicetus) looked a lot like a dog.

    You don't need a complete understanding of the DNA of the entire lineage. You just need an understanding of the lineage, as expressed in fossil remains and molecular clocks within the DNA. (The clocks give you distances to most recent common ancestors.)
  16. AlphaNumeric Fully ionized Moderator

    Utterly false.

    Mutations can involve copy errors and replication errors. For example, a gene sequence can be duplicated, so that rather than say ABCDEFG you end up with ABCDECDEFG, the sequence CDE gets made twice by mistake. Now the first CDE and the second CDE can mutate differently, to say ABCGEBDEFG. Thus new DNA sequences are created.

    This is all pretty basic stuff. A casual read of pop science books on evolution will inform you of this. I haven't studied biology since I was 16 (I'm now 28) so if I'm aware of this stuff it's not exactly hard to find out, all you have to do is bother to listen.
  17. Reiku Banned Banned

    ... oh damn... what's it called... something like ''punctuated equilibrium''...

    Why can't a species arise from this?
  18. Arioch Valued Senior Member

    So is this going to turn into another "why evolution is wrong" threads, spearheaded by people who don't even have a grasp on basic biology let alone genetics? That's where this seems to be headed, and it's a damn shame too because this thread would be such a nice opportunity to get into both basic genetics and punctuated equilibrium rather than swatting down the same old arguments yet again.
  19. James R Just this guy, you know? Staff Member


    No, that's wrong.

    This is wrong, too. All life evolved from a common ancestor, and today we have everything from single-celled bacteria to blue whales.

    But any mutation involves changing the DNA from its "original" state to a new state, so your distinction is quite useless.
  20. wlminex Banned Banned

    James R Quote: "But any mutation involves changing the DNA from its "original" state to a new state, so your distinction is quite useless.

    IMPO: "DNA old state + Casimir Effect(s) = DNA new state"
  21. Arioch Valued Senior Member

    What the hell are "casimir effect(s)"? Is that psuedoscience for "bullshit"?
  22. matthew809 Registered Senior Member

    Originally Posted by matthew809
    "The bacteria does not create new DNA from thin air."

    The length of DNA is not what's important; it's the information in the DNA which matters. This DNA information directs the processes of change which we can observe.

    If DNA gets longer, then you have to ask where did it come from? Did this "extra" DNA spontaneously come into existence, or is it the explicit product of former DNA?

    Does it make sense to think that DNA could randomly(without the direction of existing DNA instruction) get longer or shorter in length, and still function? Do you believe DNA is really that unimportant?
  23. origin It keeps getting funnier.... Valued Senior Member

    Mutations occur - this is a fact.
    A mutated strand of DNA is new DNA (in that it is different than the original). So in essence - yes, bacteria create DNA from 'thin air'.

    Most mutations are most likely repaired by the DNA.
    Many mutations are minor and have no affect on the organism
    Some mutations are harmful or fatal.
    Rarely mutations are beneficial. The benifical mutations increase the likelyhood of survival of the individual which passes on this mutation to future generations. We call this evolution. Seems pretty straight forward to me.

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