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Re: [OriginsTalk]

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  • weresmith3@cs.com
    BELIEF is thinking in the absence of available data. Lowell,you point out something though. What would a transitional giraffe look like-the Okapi? Nature
    Message 1 of 7 , Mar 1, 2002
      BELIEF is thinking in the absence of available data.
      Lowell,you point out something though.
      What would a transitional giraffe look like-the Okapi?
      Nature experiments and occaisionally will come up with some thing that fills another niche.
      If an species cannot fill an available niche it goes extinct.
      Sadly,we are watching one such species who is failing to adapt and will likely go extinct--the giant panda.

      GUY
    • Chris Ashcraft
      The Panda is not going extinct because it can not adapt to a niche, but rather because it already has and now can evolve no further. Its habitat is dwindling
      Message 2 of 7 , Mar 2, 2002
        The Panda is not going extinct because it can not adapt to a niche, but rather because it already
        has and now can evolve no further. Its habitat is dwindling but the process of adapting to some
        extent leads to an evolutionary dead-end for the organism. The variability it was created with
        diminishes upon selection. This has been adequately demonstrated by breeders for generations.

        Selection creates a pure-breed. The organism originally possesses variability which upon
        selection, for or against, is reduced. The ability to produce offspring with variable forms is
        tremendous at the beginning of the breeding history, but if selection is maintained eventually the
        population is only able to produce progeny which are identical to the parents.

        At our present state of knowledge, genetic recombination remains theoretically limitless in its
        ability to produce evolutionary variability, and selection may simply be able to remove the
        variants from the population quicker than they are generated. But it is clear that offspring
        variability created during meiosis diminishes upon selection, and eventually the organism only
        reproduces in a pure-breed manner.

        --- weresmith3@... wrote:

        > If an species cannot fill an available niche it goes extinct.
        > Sadly,we are watching one such species who is failing to adapt and will
        > likely go extinct--the giant panda.

        =====
        Chris Ashcraft
        Creation Science Resource
        http://nwcreation.net

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      • Gordon Swift
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        Message 3 of 7 , Mar 3, 2002
          > -----Original Message-----
          > From: Chris Ashcraft [mailto:ashcraft@...]

          The variability it was created with diminishes
          > upon selection. This has been adequately demonstrated by
          > breeders for generations.

          But it is clear that offspring variability created
          > during meiosis diminishes upon selection, and eventually the
          > organism only reproduces in a pure-breed manner.
          >

          ---------------------------

          References?

          I'd like to see some peer reviewed references showing that subsequent
          generations of organisms show a trend of decreasing genetic variability.




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        • David Kristján Simpson
          Hello Gordon, Actually this was a problem Darwin confronted in On the Origin of Species and he did not have the benefit of Mendelian genetics as an
          Message 4 of 7 , Mar 3, 2002
            Hello Gordon,


            Actually this was a problem Darwin confronted in "On the Origin of Species"
            and he did not have the benefit of Mendelian genetics as an explanatory
            tool.

            This primitive belief, still followed by some animal breeders, is called
            Blending Inheritance.

            Perhaps there is some confusion with the statistical use of Regression to
            the Mean.

            One studies this in Population Genetics.

            Punctuated Equilibrium relies on its ramifications.


            David Kristján Simpson


            ----- Original Message -----
            From: "Gordon Swift" <sison13@...>
            To: <OriginsTalk@yahoogroups.com>
            Sent: Sun 03 March 2002 17:53
            Subject: RE: [OriginsTalk] Limits to Evolution


            >
            >
            > > -----Original Message-----
            > > From: Chris Ashcraft [mailto:ashcraft@...]
            >
            > The variability it was created with diminishes
            > > upon selection. This has been adequately demonstrated by
            > > breeders for generations.
            >
            > But it is clear that offspring variability created
            > > during meiosis diminishes upon selection, and eventually the
            > > organism only reproduces in a pure-breed manner.
            > >
            >
            > ---------------------------
            >
            > References?
            >
            > I'd like to see some peer reviewed references showing that subsequent
            > generations of organisms show a trend of decreasing genetic variability.
            >
            >
            >
            >
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          • Chris Ashcraft
            A pure-breed is an organisms with limited genetic variability. That is what you pay for when you buy a registered animal or plant line. You are buying a
            Message 5 of 7 , Mar 9, 2002
              A pure-breed is an organisms with limited genetic variability. That is what you pay for when you
              buy a registered animal or plant line. You are buying a guarantee that the traits, which have been
              selected, will not segregate out in subsequent generations. The registration is verification that
              its genotype is free from related variability, and the offspring from its lineage will possess a
              known phenotype for the characteristics in question.

              A pure-breed is genetically homozygous, or an individual from which alternative alleles for the
              genes in question will no longer be distributed to offspring. Selection for specific
              characteristics eliminates alleles that produce other varieties. Natural selection in this respect
              works in the exact same way as artificial breeding. Following a period of selection, the organisms
              ability to produce a spread of traits could be lost forever excepting the creation of more alleles
              through crossovers or mutation.

              To generate a homozygote for any characteristic; breed two organisms possessing the desired trait,
              and one of their children will likely be pure-bred for a related gene. Simply look for a family
              whose entire progeny possess the trait, and at least one of their parents were homozygote. If its
              a detectable gene, then isolate tissue from the offspring and if all possess the gene, the parent
              is a homozygote and from that organism a pure blood-line begins. If you know the parents are
              heterozygote, or each have only one copy of the gene, then it is expected for 25% of their
              offspring to be homozygote(AA, Aa, aA, aa). If you subsequently select the homozygote and mate it
              with another heterozygote; 75% of the offspring will be homozygote(Aa, aa, aa, aa).

              Although few characteristics can be reduced to a single pair of alleles, it is absolutely clear
              that selection (inbreeding selected features) will generate and then multiply genetic homozygotes
              for the related genes within the population. If selection persists, these homozygotes will rapidly
              become predominant in the population, and the group as a whole will become more limited
              genetically as a result of the selection. That's how evolution works. Nature selects from a pool
              of alleles, and the resulting homozygotes are genetically pure bred for the features which gave
              the organisms the specific adaptation.

              Evolution through meiotic recombination or classic genetics is largely a one-way street, and
              unless freak mutations rescue organisms, which are already adapted pure breeds like the Panda,
              they will certainly go extinct if their environment diminishes. Unfortunately, the evolutionists
              must forget that offspring variability is created by meiotic recombination, and drastically
              reduced by selection in this way. They must instead insist that a continuous stream of mutations
              were responsible for adaptations like the finches.

              Selection removes genes from the population, and eventually eliminates the organisms ability to
              produce progeny which differ. The galapagos finch varieties are the result of genetic
              recombination just like all the domestic breeds, and now just exist as several naturally pure-bred
              species. Evolution occur because nature chooses (inbreeds) particulars characteristics from
              existing variability, and following an extended selective breeding the entire population becomes
              homozygous. They are more fit for the specific conditions, but less able to change as a result.

              Constructing a homozygote:
              http://lifesci.rutgers.edu/~mcguire/genetics2000/constructing_a__homozygote.htm

              Inbreeding and linebreeding
              http://bowlingsite.mcf.com/Genetics/Inbreeding.html

              Segregation of Identical Homozygotes - Slide
              http://www.kursus.kvl.dk/shares/vetgen/_Popgen/genetics/4/4/sld009.htm


              --- Gordon Swift <sison13@...> wrote:
              > References?
              >
              > I'd like to see some peer reviewed references showing that subsequent
              > generations of organisms show a trend of decreasing genetic variability.



              =====
              Chris Ashcraft
              Creation Science Resource
              http://nwcreation.net

              __________________________________________________
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            • Steve Hallam
              ... It is true that mutation is important for evolution. Fortunately, the effects of mutation on the rapidity of evolution are well established. HIV for
              Message 6 of 7 , Mar 10, 2002
                > Evolution through meiotic recombination or classic
                > genetics is largely a one-way street, and
                > unless freak mutations rescue organisms, which are
                > already adapted pure breeds like the Panda,
                > they will certainly go extinct if their environment
                > diminishes. Unfortunately, the evolutionists
                > must forget that offspring variability is created by
                > meiotic recombination, and drastically
                > reduced by selection in this way. They must instead
                > insist that a continuous stream of mutations
                > were responsible for adaptations like the finches.


                It is true that mutation is important for evolution.
                Fortunately, the effects of mutation on the rapidity
                of evolution are well established. HIV for example
                has a high rate of mutation making it especially
                effective at resisting man made chemical attacks. It
                is important to remember that some mutations are
                beneficial. Mutations are like experiments with
                nature selecting those that work. We don't need magic
                to explain the earth's biodiversity especially when
                have such well established natural explanations. So
                much for the limits to evolution.









                --- Chris Ashcraft <ashcraft@...> wrote:
                > A pure-breed is an organisms with limited genetic
                > variability. That is what you pay for when you
                > buy a registered animal or plant line. You are
                > buying a guarantee that the traits, which have been
                > selected, will not segregate out in subsequent
                > generations. The registration is verification that
                > its genotype is free from related variability, and
                > the offspring from its lineage will possess a
                > known phenotype for the characteristics in question.
                >
                >
                > A pure-breed is genetically homozygous, or an
                > individual from which alternative alleles for the
                > genes in question will no longer be distributed to
                > offspring. Selection for specific
                > characteristics eliminates alleles that produce
                > other varieties. Natural selection in this respect
                > works in the exact same way as artificial breeding.
                > Following a period of selection, the organisms
                > ability to produce a spread of traits could be lost
                > forever excepting the creation of more alleles
                > through crossovers or mutation.
                >
                > To generate a homozygote for any characteristic;
                > breed two organisms possessing the desired trait,
                > and one of their children will likely be pure-bred
                > for a related gene. Simply look for a family
                > whose entire progeny possess the trait, and at least
                > one of their parents were homozygote. If its
                > a detectable gene, then isolate tissue from the
                > offspring and if all possess the gene, the parent
                > is a homozygote and from that organism a pure
                > blood-line begins. If you know the parents are
                > heterozygote, or each have only one copy of the
                > gene, then it is expected for 25% of their
                > offspring to be homozygote(AA, Aa, aA, aa). If you
                > subsequently select the homozygote and mate it
                > with another heterozygote; 75% of the offspring will
                > be homozygote(Aa, aa, aa, aa).
                >
                > Although few characteristics can be reduced to a
                > single pair of alleles, it is absolutely clear
                > that selection (inbreeding selected features) will
                > generate and then multiply genetic homozygotes
                > for the related genes within the population. If
                > selection persists, these homozygotes will rapidly
                > become predominant in the population, and the group
                > as a whole will become more limited
                > genetically as a result of the selection. That's how
                > evolution works. Nature selects from a pool
                > of alleles, and the resulting homozygotes are
                > genetically pure bred for the features which gave
                > the organisms the specific adaptation.
                >
                > Evolution through meiotic recombination or classic
                > genetics is largely a one-way street, and
                > unless freak mutations rescue organisms, which are
                > already adapted pure breeds like the Panda,
                > they will certainly go extinct if their environment
                > diminishes. Unfortunately, the evolutionists
                > must forget that offspring variability is created by
                > meiotic recombination, and drastically
                > reduced by selection in this way. They must instead
                > insist that a continuous stream of mutations
                > were responsible for adaptations like the finches.
                >
                > Selection removes genes from the population, and
                > eventually eliminates the organisms ability to
                > produce progeny which differ. The galapagos finch
                > varieties are the result of genetic
                > recombination just like all the domestic breeds, and
                > now just exist as several naturally pure-bred
                > species. Evolution occur because nature chooses
                > (inbreeds) particulars characteristics from
                > existing variability, and following an extended
                > selective breeding the entire population becomes
                > homozygous. They are more fit for the specific
                > conditions, but less able to change as a result.
                >
                > Constructing a homozygote:
                >
                http://lifesci.rutgers.edu/~mcguire/genetics2000/constructing_a__homozygote.htm
                >
                > Inbreeding and linebreeding
                > http://bowlingsite.mcf.com/Genetics/Inbreeding.html
                >
                > Segregation of Identical Homozygotes - Slide
                >
                http://www.kursus.kvl.dk/shares/vetgen/_Popgen/genetics/4/4/sld009.htm
                >
                >
                > --- Gordon Swift <sison13@...> wrote:
                > > References?
                > >
                > > I'd like to see some peer reviewed references
                > showing that subsequent
                > > generations of organisms show a trend of
                > decreasing genetic variability.
                >
                >
                >
                > =====
                > Chris Ashcraft
                > Creation Science Resource
                > http://nwcreation.net
                >
                > __________________________________________________
                > Do You Yahoo!?
                > Try FREE Yahoo! Mail - the world's greatest free
                > email!
                > http://mail.yahoo.com/
                >


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              • Gordon Swift
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                Message 7 of 7 , Mar 13, 2002
                  > -----Original Message-----
                  > From: Chris Ashcraft [mailto:ashcraft@...]

                  >
                  > Constructing a homozygote:
                  > http://lifesci.rutgers.edu/~mcguire/genetics2000/constructing_
                  a__homozygote.htm

                  Inbreeding and linebreeding
                  http://bowlingsite.mcf.com/Genetics/Inbreeding.html

                  Segregation of Identical Homozygotes - Slide
                  http://www.kursus.kvl.dk/shares/vetgen/_Popgen/genetics/4/4/sld009.htm


                  ---------------------

                  Did you read those sites? You claim that natural selection in
                  populations decreases genetic variability, then as evidence you supply
                  websites about intentional inbreeding.

                  To get this overwith, I'm going to show how you are actually partially
                  right. Selection, especially sudden, intense selection, can decrease
                  the diversity of a population. Intense selection means that the
                  surviving offspring will come from a relatively low number of parents,
                  thus the subsequent generations will be more closely related than
                  before.

                  But, we also have mechanisms for increasing genetic diversity like
                  crossing over, mutation, polyploid speciation, genetic drift, species
                  radiating into new niches, etc. To ignore these is a guaranteed
                  misinterpretation the dynamics of natural populations. After all, how
                  the heck is a polyploid speciation a decrease in genetic diversity?




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