Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Evolution question

  1. Jul 21, 2010 #1
    I have been reading Charles Darwins Book "The Beginning Of Species" and it has got me thinking. Would it be possible to breed a NEW species of Mammal within a life time?
    i was thinking about using mice because their breeding cycle is quite short.

    Does anyone have any knowledge of anyone trying this with Mammals?

    The Reason that i got to thinking about this is that i breed dogs and in every litter i see large variations let alone the massive variations that are possible after a few generations.

    I was thinking large variations would be achievable quite quickly if the environment was changed dramatically. Of course the changes would only take place if the mice survived and reproduced with the environment change.
  2. jcsd
  3. Jul 21, 2010 #2
    It seems unlikely, even with the short breeding cycle of mice that this could be achieved in a normal human lifetime. We have been breeding dogs for several thousand years and they are still the same species.

    Changing the environment rapidly will have absolutely no effect on the range of variations. The environment does not determine the variations the exieting gene pool does. the environment selects from that pool based upon fitness for that pool. (Obviously the environment has an influence in terms of factors such as radiation that promote mutations, but I don't believe this is what you were thinking of.)
  4. Jul 21, 2010 #3
    I understand that it is understood that evolution takes place over millions of years
    but i read where somewhere in europe there was a famine in the 1950's i think around the time of the war. The babies that were in the womb and born at that time were a large percentage smaller than the babies that were born either before or after that time. (which is an adaption for the lack of food right?) The interesting thing is that the women that were born small during that time also have low birth weight babies themselves and i heard it is now happening to the women in the third generation after the famine....

    I'm not a expert in the field of genetics or evolution but that sounds like an adaption to the environment to me...
  5. Jul 21, 2010 #4


    User Avatar

    Staff: Mentor

    Please post the peer reviewed studies on this. I've read the opposite, that human size goes up and down depending on the food available.

    It's not an evolutionaty adaptation that poor nutrition results in lower weight babies.
  6. Jul 21, 2010 #5


    User Avatar
    Gold Member

    His story is true, but it's an example of epigenetics. It's about gene expression, not a change in the genes.

    So all your dogs could have the same genes (they don't, I'm sure) and each of them will express a different set.

    In other words, you don't express all your genes, and different people who share genes with you may not express them the same ones you do.
  7. Jul 21, 2010 #6
    Yes Epigenetics...just thinking out loudly... if it is possible to have such great change within one generation through the change of dietary intake. What would be possible over ten or fifty generations. I realize that this change was done without changing any genes, but what i am wondering is... if the environment continually changes, in one direction, would that force a mutation to show itself quicker than if there was with no change in the environment?
  8. Jul 22, 2010 #7
    Last edited by a moderator: May 4, 2017
  9. Jul 23, 2010 #8
    Thanks Physics dude.

    So it has happened in nature recently....
    Is there anyone doing experiments at the moment with mammals?
  10. Jul 23, 2010 #9


    User Avatar
    Gold Member

    I'm not sure, but I doubt it. I think mutation is pretty chaotic, if not random. After the mutation, the environment (including the organisms own body) then "decides" which mutations live.
  11. Jul 23, 2010 #10
    For a start, you have to decide what counts as a new species. There are different definitions depending on whose point of view you take. It is perfectly possible to create a "new" species almost within a generation if you have access to genetic material that permits you to produce lines that are mutually sterile. By some definitions, all you need do is produce lines that do not readily mate. Some breeds of dogs are for practical purposes mutually sterile, in spite of people who claim that there is just one species of domestic dog.

    And what do you make of ring species? They are a bit of a logical problem, don't you think?

    In taxonomy, to define certain taxa, other than in terms of human logical constructs, sometimes is such a vexed problem that to argue the point is hardly worth the trouble. Usually what people think in terms of amounts to essentialism, and nature is no friend of essentialists. It is better to stop and consider carefully what your operative objectives are, and if you cannot define usefully them in objective terms, then you probably are in the toils of an arbitrary semantic construct rather than an any empirical reality of nature?

    The distinctions between particular taxa might well meet particular logical criteria, but without being worth serious interest.
  12. Jul 24, 2010 #11
    Lets take the extreme: you want to engineer a novel species of mammal so unique that the issues raised by Jon Richfield don't apply: that would require technology that is not available right now. You would need to model an organism on the genetic level and see that it WORKS, that it can live, and reproduce, and you would need to do so either from the ground-up, or through serious recombination of existing genomes.

    You would have to control how and when the genes you want are expressed as well, which... is tough. Lets say you want to make an egg-laying marsupial-like mammal with feathers and fur, and flightless wings. You can't just crossbreed a Platypus, Bat, Bird, and Kangaroo. You would need a complete understanding of the genomes of each source, and how the expression of those genes leads to the traits you want to have in your species. That would require computer power that is still a dream, viruses or other means to put together this chimeric thing in a single genome through many stages... so... no.

    Consider Taxonomy as Jon says... of three pufferfish: one is without a toxin, another carries toxin in its ovaries and a few other organs, and a third has that same toxin throughout its flesh. They look nearly identical, and this distinction was only brought to light as a result of the 2007 "monkfish" fiasco in Chicago.
  13. Jul 25, 2010 #12
    This whole speciation thing is a very tricky, not to say treacherous subject. It becomes doubly so when we combine disciplines and evidence from various sources in attempting to determine the biology of the past in the study of palaeontology. Note that it is easy to confuse estimates of the average "longevity" of species in the fossil record, in which durations of tens of millions of years (unusually) all the way down to less than 1 million years occur, with the amount of time it takes for a new species to emerge.
    Quite commonly species appear and disappear in the fossil record too abruptly for us to put a time on it. They simply appear (sometimes as a single fragmentary fossil) and disappear (no fossil, fragmentary or otherwise!) Remember too, that the degree of distinction that we would require to recognise fossils as being of different species is of altogether a different order from what we can tell from the evidence of our eyes in looking at living species. There are plenty of species about us to day, that we would regard as single species if we knew them only as fossils. It would take an alert palaeontologist with good material, preferably plenty of good material, to tell a lion from a tiger. Modern taxonomists are under no such constraints, and even the laity can tell them apart. If we could see the species in real life that have contributed the fossils that our palaeontologists have recognised, we probably would double or quadruple the number of species. Palaeontologists are limited to using very constrained evidence in assigning species to fossils.
    One implication is that only comparatively radical physical differences show up distinctions between species in fossil material. This means that when we recognise fossil species, they certainly will have taken a long time to emerge as distinct. Even so, their emergence in the fossil record generally looks very abrupt to us.
    Now, when we speak of a new species forming or emerging, the operative period of time it takes is not the duration of the species in the fossil record, but the amount of time it takes for the transition, and I hope I have made it plain that the transition period is in comparison so short that we usually lose it when the fossil record blinks.
    When on the other hand, we speak of living species, we usually are thinking of comparatively tiny changes that are sufficient to create differences in appearance, physiology, or behaviour, by which we may tell them apart, or that discourages them from interbreeding. Often a single gene, or a small set of genetic differences is sufficient to cause this, and such a change might happen in a few generations. For many species that means just a few years.
    This is not to say that speciation is a trivial concept, or a trivial process, nor yet of trivial importance, but I do want to emphasise that we have to be very careful in our thinking on the subject.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook