Re: Evolution & Identity of the ID designer

From: bivalve (
Date: Tue Dec 03 2002 - 12:51:29 EST

  • Next message: Adrian Teo: "RE: Evolution & Identity of the ID designer"

    >Until, and unless, a firm theory is proposed and real data supports
    >it (For example, scientists induce circumstances which give rise to
    >an evolutionary new species) then it mostly a matter of philosophy
    >and conviction.<

    Humans have been producing new species for thousands of years via
    domestication and artifical selection. Speciation is also frequently
    observed in progress in nature. Deliberate production of new species
    in the lab has also been achieved many times; most recently:

    Duncan Greig, Edward J. Louis, Rhona H. Borts, Michael Travisano.
    2002. Hybrid Speciation in Experimental Populations of Yeast.
    Science, Volume 298, Number 5599, Issue of 29 Nov 2002, pp. 1773-1775.

    Abstract: Most models of speciation require gradual change and
    geographic or ecological isolation for new species to arise.
    Homoploid hybrid speciation occurred readily between Saccharomyces
    cerevisiae and Saccharomyces paradoxus. Hybrids had high
    self-fertility (about 82%), low fertility when backcrossed to either
    parental species (about 7.5%), and vigorous growth under different
    thermal environments that favored one or the other of the parental
    species. Extensive karyotypic changes (tetrasomy) were observed in
    the hybrids, although genic incompatibilities accounted for 50% of
    the variation in self-fertility.

    In other words, by hybridizing two species of yeast, they obtained
    new kinds of yeasts that were able to reproduce within the new
    strain, but had limited reproductive compatibility with either
    parent. Creation of a new species in this manner is almost
    instantaneous and thus it makes up most of the unambiguous examples
    of the full creation of new species. A more gradual isolation of two
    populations makes it much harder to draw a firm line as a point at
    which new species exist. We can see this process in progress, e.g.
    with the hawthorn fruit flies that are evolving into apple flies
    instead (they mate on the fruit, so a strictly hawthorn fly and a
    strictly apple fly wil never get together), but it is difficult to
    say when we can recognize it as two species.

    Again, this does not prove universal common descent, but it does show
    that organisms indeed change over time.

         Dr. David Campbell
         Old Seashells
         University of Alabama
         Biodiversity & Systematics
         Dept. Biological Sciences
         Box 870345
         Tuscaloosa, AL 35487 USA

    That is Uncle Joe, taken in the masonic regalia of a Grand Exalted
    Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at
    Droitgate Spa

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