RE: Definition of "Species"

From: Woodward Norm Civ WRALC/TIEDM (Norm.Woodward@robins.af.mil)
Date: Tue Feb 19 2002 - 17:17:06 EST

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    But, all in all, you have confirmed my contention: that though they cannot
    provide a general definition of "species" or "speciation," evolutionists
    know it when they see it.

    Yet they are quick to hang creationists out to dry when such an approach is
    used to define "kinds."

    * I have not seen the new varieties of bacteria called species.

    But have you seen the their creation cited as a proof of "the theory of
    evolution"? If new species are not being created, then how is the theory
    being confirmed?

    >A horse and donkey can be crossed to produce a mule, but the mule is almost
    always sterile.

    Had anyone suggested that the caballus and the asinus were not of different
    species?

    I am aware of the problems of interspecies breeding. I am just amazed how
    speciation claims seem to be made based on, it would appear, rather
    subjective classification.

    BTW, has any reputable biologists (lately) crossed politically correct
    barriers, and implied that human populations of different races may be of
    different species? Surely, when considering, at least historically,
    morphological differences and geographic and social barriers prohibiting
    "intermarriage," and the various definitions of "species" which you have
    proposed, this conclusion must be the "elephant in the parlor," that
    everyone sees, but no one will mention.

    Of course, I would not subscribe to such a concept, but, then again, I am
    not sure I agree with several of your suggested definitions of "species."

    (I hope I have not offended anyone's sensitivities, but sometimes to
    discredit a concept, you have to extend it its illogical conclusion.)

    Norm Woodward
    Warner Robins

    -----Original Message-----
    From: bivalve [mailto:bivalve@mail.davidson.alumlink.com]
    Sent: Tuesday, February 19, 2002 2:53 PM
    To: asa@calvin.edu
    Subject: Definition of "Species"

    >>... the common complaint that "kinds" in the OT is rather
    vague at best, not aligning well with modern classification
    categories.<<

    I think that this principally tells us not to claim that the Bible
    provides a limit on the possible extent of evolution in its
    use of "kind" or similar terms, as there is no definition of
    kind. In contrast, Huse cites Gish as declaring that kinds
    are roughly equivalent to a family.

    >But I have found that the prime unit of evolution theory,
    "species," as in "Origin of the....," is often more than a little
    flexible, especially when defending evolution. I mean,
    kids, and gullible adults, are told that new resistant
    "species" of bacteria are appearing every day, this "proving"
    evolution. <

    I have not seen the new varieties of bacteria called
    species. The application of the term species to bacteria is
    indeed problematic. There is a separate nomenclatural
    code for bacteria, independent of the codes for plants and
    for animals. If you were to try to define species as
    reflecting a certain level of genetic differentiation, the
    so-called species of bacteria would probably come out
    more equivalent to family-level variability in animals.
    Morphologically, there are only a limited number of features
    available for distinguishing bacterial species, and this
    typically requires being able to grow and study colonies. If
    it does not like petri dishes, then identifying a species is
    difficult. Another problem is that bacteria are promiscuous
    in swapping genes. A stray bit of DNA is relatively easily
    taken up by a bacterium. Does this count as
    interbreeding?

    >But, the dictionary definition of species, "
    category...comprising related organisms or populations
    potentially capable of interbreeding...," fails when
    categorizing asexual organisms. The temptation to equate
    "strains" and "species" seem a little too hard to resist, or
    justify. <

    The definition of species is highly debated in biology, and
    its application to asexual organisms is especially
    problematic. On the other hand, there is some consensus
    on recognizing species. A study on an Australian
    aboriginal community that relied extensively on shellfish
    found that the correlation between what they had separate
    names for and what malacologists recognize as distinct
    species was very good. Species seem to be real entities,
    but how to define them?

    Several species definitions are currently in use by
    biologists. Although a general underlying idea is genetic
    continuity, the details differ. Perhaps the most widely used
    is the morphological species concept. Things that look
    different are presumed to be different species. What
    constitutes a valid difference may be problematic.
    However, in many cases, direct testing of reproductive
    compatibility is not an option. Extinct organisms do not
    interbreed even with members of the same species
    anymore. In other cases, it is theoretically possible but not
    feasible. Attempting to get every plausible pair of varieties
    to reproduce would require a lot of time and money.

    The biological species concept is what your dictionary was
    aiming at. Organisms that are reproductively compatible
    are considered conspecific. However, this leaves open the
    question of just how compatible is enough? For example,
    in the leopard frogs, it is possible to fertilize eggs of a
    female from one region with sperm from a male from
    another region. However, the female from one region will
    not respond to the croak of a male from another region,
    and so in nature the two would never get together. The
    Baltimore Oriole and the Bullock's Oriole were
    synonymized as one species when occasional
    hybridization was observed. However, longer-term studies
    revealed that the offspring seemed to not do as well as
    pure-blooded individuals, and more recent molecular
    studies have even indicated that they are not each other's
    closest relative. A horse and donkey can be crossed to
    produce a mule, but the mule is almost always sterile. An
    indirect way to look at this is to look for distinctive genetic
    markers in a population. If it is freely interbreeding with
    other populations, we expect to see genetic markers
    shared between the populations. If each population has
    distinct genetic features, then it looks as though DNA is not
    being shared and the groups might be separate species.
    However, the amount of interbreeding that is necessary to
    produce sharing in genetic markers (and conversely, the
    amount of interbreeding that can occur while genetic
    differences are amintained) seems variable.

    Another concept is the phylogenetic species concept. It
    seeks to identify species as evolutionarily distinct entities.
    Proponents of this view tend to claim that it is better
    because it is phylogenetic and have not done much to deal
    with the problem of testing whether one has correctly
    recognized evolutionarily distinct entities.

    For asexually reproducing organisms within predominantly
    sexually reproducing groups, individuals with a common
    genetic origin are generally considered conspecific.
    Several kinds of animals, including many lizards, some
    amphibians and fishes, and assorted invertebrates, can
    produce asexually reproducing partheneogenetic
    individuals through hybridization between two species.
    This offspring is reproductively isolated from either parent,
    and so seems to qualify as a new species. Its offspring
    are genetically identical to it, except for mutations, and so
    seem reasonably identified as conspecific. Other
    individuals produced by the same cross (i.e., a male of
    species a and female of species b) are morphologically
    and physiologically similar, and so are also considered
    conspecific. In plants it becomes more complex because
    the hybrid often is capable of reproducing sexually with
    other hybrids (including its own asexually produced
    offspring), and some plants can self-fertilize as well.
    However, the hybrid cannot reproduce with either parent,
    although in some cases yet another hybrid can be
    produced.

    >But I have found scientists like to put a spin on the
    definition concerning larger critters. I had a heated
    discussion a year ago about some new species of fish
    supposedly found in Canada. Trying to stifle this
    evolutionist's enthusiasm concerning this new proof of
    "speciation," I inquired whether this fish could mate with a
    member of the species from which it "evolved." I was told
    that, for what ever reason, these critters like to stay with
    "their own kind." So I suggested trying artificial
    insemination. "Oh my goodness, no! Why would anyone
    want to do THAT?" was basically the response.<

    This gets back to the question of the level of separation
    necessary to recognize species. There are fish, shells,
    crustaceans, etc. living on either side of Panama that look
    very similar, yet the chance of two getting together from
    either side in nature is nearly nil. They have been
    separated for at least about 2 million years (depending on
    how shallow a connection they were willing to cross).
    Some are considered separate species, but some are
    considered to still represent the same species. If two
    individuals theoretically could interbreed, but there is an
    uncrossable barrier between them, are they conspecific? If
    they theoretically could interbreed, but refuse to do so
    because behavioral cues are missing, are they
    conspecific? A well-studied example similar to your fish
    comes from some fruit flies. They originally lived on
    hawthorn berries as larvae, and mating takes place on the
    berry. Some have now taken to living on apples instead.
    Apples ripen at a slightly different time and take longer to
    rot away, so there are a number of changes in habits to
    make, in addition to the key factor of looking for mates on
    apples instead of on hawthorn berries. At least one
    genetic change has been observed as well, and there is a
    strong tendency for apple-reared young to mate on apples
    and hawthorn-reared young to mate on hawthorns. Are
    they two species yet? A more extreme situation develops if
    artificial insemination theoretically would work, but
    reproduction is physically impossible. For example, if all
    dogs except chihuahuas and Great Danes were
    eliminated, no Greathuahuas would be produced naturally.
    (As is, the varieties of dogs are considered conspecific
    because there are so many intermediates.) For practical
    purposes, they would be separate species. A different sort
    of example comes from mice in isolated valleys in Italy.
    They all look like ordinary mice, but many populations have
    chromosomal rearrangements. If a mouse from one valley
    with one chromosomal configuration mates with a mouse
    from another valley with a different chromosomal
    configuration, the offspring will probably be infertile
    because the chromosomal mismatch prevents gamete
    production. Are these separate species?

    >What amazes me is, at other sites, of course,
    evolutionists tend to try to come off with a rather "fearing
    neither man or God" persona, but when it comes to proving
    speciation, they seem to claim that if interbreeding is not
    achieved through soft music, and a candle-lit dinner, then
    the results are unwarranted, illegal, and possibly, invalid.<

    The general tendency has been to restrict the definition of
    species, so that a lack of interbreeding simply through
    behavioral differences is recognized as a species-level
    difference. A good example of this can be found by
    comparing older and newer field guides to birds. Many of
    the old forms now split into two or more species look
    similar throughout their range but produce distinctive
    songs in different parts of their ranges. Females expecting
    one song usually won't respond to the other song.

    Except in the case of hybridization producing reproductive
    isolation in a single step, speciation will generally be a
    process rather than an abrupt event. We see populations
    at several different stages of the process, so it is difficult to
    draw a precise line as to which ones have truly split and
    which ones are not quite there yet.

        Dr. David Campbell
        Old Seashells
        46860 Hilton Dr #1113
        Lexington Park MD 20653 USA
        bivalve@mail.davidson.alumlink.com

    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 Droigate Spa

    ---------- Original Message ----------------------------------
    From: Woodward Norm Civ WRALC/TIEDM
    <Norm.Woodward@robins.af.mil>
    Date: Tue, 19 Feb 2002 12:30:31 -0500

    >Adrian Teo did an admirable job of trying to defend us
    OECs, but this is a
    >hard room to please...
    >
    >But one item that he seemed to be taken to task is the
    common complaint that
    >"kinds" in the OT is rather vague at best, not aligning well
    with modern
    >classification categories.
    >
    >But I have found that the prime unit of evolution theory,
    "species," as in
    >"Origin of the....," is often more than a little flexible,
    especially when
    >defending evolution.
    >
    >I mean, kids, and gullible adults, are told that new
    resistant "species" of
    >bacteria are appearing every day, this "proving" evolution.
    But, the
    >dictionary definition of species, " category...comprising
    related organisms
    >or populations potentially capable of interbreeding...," fails
    when
    >categorizing asexual organisms. The temptation to
    equate "strains" and
    >"species" seem a little too hard to resist, or justify.
    >
    >But I have found scientists like to put a spin on the
    definition concerning
    >larger critters. I had a heated discussion a year ago
    about some new
    >species of fish supposedly found in Canada. Trying to
    stifle this
    >evolutionist's enthusiasm concerning this new proof of
    "speciation," I
    >inquired whether this fish could mate with a member of
    the species from
    >which it "evolved." I was told that, for what ever reason,
    these critters
    >like to stay with "their own kind." So I suggested trying
    artificial
    >insemination. "Oh my goodness, no! Why would anyone
    want to do THAT?" was
    >basically the response.
    >
    >And I hear this rationale over and over...such as claims
    that many breeds of
    >dog is of a different "species." When they say that a
    Chihuahua can no
    >longer interbreed with a Great Dane, I ask has it been
    tried using
    >artificial insemination, with the Great Dane carrying the
    litter, of course.
    >The answer was the same as above.
    >
    >What amazes me is, at other sites, of course,
    evolutionists tend to try to
    >come off with a rather "fearing neither man or God"
    persona, but when it
    >comes to proving speciation, they seem to claim that if
    interbreeding is not
    >achieved through soft music, and a candle-lit dinner, then
    the results are
    >unwarranted, illegal, and possibly, invalid.
    >
    >I would like any comments about this observation.
    >
    >Norm Woodward
    >Warner Robins Georgia
    >
    >
    >
                    



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