Species Speciation And The Gen
SPECIES, SPECIATION AND THE GENESIS KIND
By David N. Menton
St.Louis, MO 1987
In his “table talks”, Martin Luther spoke of the Greek scholar Cicero’s proof of the existence of God: “The best argument that there is a God – and it often moved me deeply – is this one that he proves from generation of species; a cow always bears a cow, a horse always bears a horse, etc. No cow gives birth to a horse, no horse gives birth to a cow, no goldfinch produces a siskin. Therefore it is necessary to conclude that there is something that directs everything thus.” (Luthers Works, No.5440, Fortress Press, Philadelphia)
As obvious as this principle of “like begets like” is in terms of human experience, a central tenet of darwinism is that in the course of time, things are very different.
Evolutionism seeks to account for the origin of ALL species, past and present, from some single hypothetical primordial life form by means of random change and natural selection. Many think that Darwin solved the problem of the origin of new species with the publication of his book ‘Origin of Species,’ in fact, Darwin didn’t even deal with the subject, much less explain it.
This failure to address what was seemingly the central question of his study stemmed from the fact that Darwin, like many of the other English “transformation|ists” of his time, did not really recognize the species as a discrete and real category of organisms. Rather, he extrapolated the continuous, but limited, variation he saw among pigeons, finches, dogs etc. to a vast and seamless continuum without limits among all organisms. Thus Darwin could say in the first edition of his Origin of Species: “I see no difficulty in a race of bears being rendered, by natural selection, more and more aquatic in their habitats, with larger and larger mouths, till a creature was produced as monstrous as a whale.”
Wisely, this outrageous statement was deleted from all subsequent editions of his book.
THE CONCEPT OF SPECIES AND THE GROWTH OF EVOLUTIONISM:
There were essentially two schools of biology in the 19th century which we might call the “typological” or German school, and the “populational” or British school. Most of the great German (and French) biologists of this time viewed the species as a true type in nature and thus considered the classification of living organisms to be hierarchal. Many of the British biologists, on the other hand, focused on the variation among individuals within a species and viewed the species as nothing more than a statistical average of the population.
This in turn led many to conclude that the entire system of classification of organisms was merely an arbitrary pattern imposed on what was in reality a continuum. It is not surprising then that the concept of the evolution of all living organisms, one from another, by continuous gradual change and natural selection flowed from the British School, while German and French naturalists were among Darwin’s strongest critics.
WHAT IS A SPECIES:
The first problem, in discussing the origin of species is to define just what a species is. Complicating the definition of a species is the use in scientific literature of terms such as: neospecies, sibling species, incipient species, subspecies and semispecies. Until nearly the later half of this century, a species was considered to be any systematic unit classified as a species by a competent systematist.
More often than not, morphology rather than ability to interbreed, was considered the primary determinant of a species. As a result of this approach, 10 potentially interbreeding varieties of Red Foxes were divided into ten separate “species” on the basis of color and geographical distribution. The Red Foxes are now considered to represent one species, Vulpes fulva, comprising 12 “subspecies.” Subspecies then is simply another name for varieties that may have morphological differences as a result of their geographical separation, but still can interbreed. Species showing great morphological variation, thus having many subspecies, are said to be polytypic.
Small rodents are among the most polytypic mammals; the southern pocket gopher, Thomomys umbrinus, for example, has 214 subspecies! Homo sapiens, on the other hand, is considered to be a monotypic species as there is great reluctance, for obvious social reasons, to consider the various races of men to be subspecies (unless they are extinct and can’t fight back like Homo sapiens, neanderthalensis).
The modern definition of a species proper tends to ignore morphological differences or similarities and focus almost entirely on whether or not a population interbreeds.
The evolutionist Francisco Ayala has defined a species as “groups of interbreeding natural populations that are reproductively isolated from other such groups.” By this widely accepted definition, two organisms could be morphologically and physiologically indistinguishable, and even capable of being cross bred in the laboratory producing fertile offspring, and yet be considered two different “species” by reason of their failure to interbreed in nature.
Such populations are referred to as “sibling species.” By this definition of species there are over 6000 species of fruit flies (Drosophila) in Hawaii alone! Many of these fruit flies are morphologically indistinguishable and many do interbreed in the laboratory to produce offspring of varying degrees of fertility.
Regrettably, the term species is not always used consistently today. The nearly 150 varieties of strikingly distinctive dog breeds recognized by the American Kennel Club are all considered to be members of the same species Canis familiaris because they all can cross breed, yet the grey wolf (Canis lupus) and the coyote (Canis latrans), themselves polytypic species, are considered to be different species though they are known to interbreed with dogs. Creationists have long felt a need for a classification that would include in one consistent category all organisms that interbreed under any conditions as well as obviously related animals that are currently reproductively isolated.
SPECIES AND THE BIBLICAL “KIND”:
The Old Testament of the Bible employs the Hebrew word min 21 times to speak of the “kinds” of animals.
In Genesis the created min were said to reproduce each after its own kind thus suggesting strict reproductive limits. It is not clear exactly where in our present system of classification we would draw the line for a min.
All birds (the class Aves) are clearly not one min, because in the 14th chapter of Deuteronomy we find min applied respectively to the raven, the ostrich, the nighthawk, the sea gull, the hawk, the little owl, the great owl, the water hen, the pelican, the vulture, the cormorant, the stork, and the heron.
On the other hand, the species classification as used today is perhaps generally more limited than the Old Testament min. It would seem appropriate to include all dogs, wolves, coyotes, jackals and dingos as a single kind or min, for example, though this group includes several different species.
In like manner, all true cattle of the genus Bos would represent one kind since they can interbreed. This would combine seven species of cattle: B. taurus (Texas longhorns, Herefords, and shorthorns), B. indicus (the zebu), B. grunniens (the yak and grunting ox), B. Gaurus (the gaur), B. frontalis (the gayal), B. banteng (the banteng) and B. sauveli (the kouprey) as all are known to hybridize. B. taurus and B. indicus, for example, have been crossed to produce the breed Santa Gertrudis, but is this a new species or an example of evolution in action?
Even the African buffalo Syncerus caffer, the American bison (Bison bison) and the European bison (Bison bonasus) can be crossed with one another, and with true cattle, suggesting that all of these animals, though representing different genus and species, could be considered to be of the cattle kind or min. All varieties of horses, asses and zebras can cross breed and in like manner could be considered a horse kind.
THE RELATIONSHIP BETWEEN EVOLUTION, NATURAL SELECTION AND SPECIATION:
Many evolutionists sight subspecies and sibling species as examples of “microevolution” implying that macro-evolution, like the presumed origin of birds from reptiles, is merely “micro-evolution” writ large, though there is no known evidence for this.
It remains a fact that no one has ever observed a species evolve into another distinctively different organism of a higher taxanomic group.
It is true, however, that new “species” have been produced in the life time of human observers, if by species we mean only hybridization, reproductive isolation or limited fecundity. In 1881, for example, Judge J.L. Logan of California crossed a raspberry, Rubus idaeus, with a blackberry, R. allegheniensis, to produce the loganberry, R. loganobaccus.
The loganberry breeds true with no
tendency to revert back to either parent and is one of many examples of a true modern hybrid in plants. Hybridization among animals is much more restricted than in plants in part because of their more specialized mode of sexual reproduction.
Outrageous animal hybrid rumors are popular, such as the scruffy dog “George” which appeared on the front page of the Denver Post, and whose owners claimed was a cross between a Pekingese dog and an Angora cat! Needless to say, this was never confirmed. It has been said that it is possible to cross almost any boney fish (teleost) with another but this is in reality only parthenogenesis, where an egg is induced to divide and produce a haploid organism (one set of chromosomes) without the sperm contributing anything to the offspring.
In classical darwinism it was speculated that new organisms would evolve by a process of random change and “survival of the fittest,” but this was a circular argument which merely stated that those organisms which survive are fit and that fitness is defined as the ability to survive.
This unsatisfactory
tautology was replaced by the neodarwinian view which proposed that it was not merely survival but differential reproduction that makes natural selection and thus evolution work. It seems hopeless, however, to even attempt to explain the origin or every individual protein, structure and trait of an organism’s phenotype or behavior in terms of differential reproduction.
Indeed, in recent
years, some have proposed that evolution occurs by a purely random process in which natural selection plays no key role at all! This has resulted from the observation that most of the genetic divergence between species observable at the molecular level appears to be nonselective and thus nondarwinian. Modern molecular biology has shown that only a small fraction of the total DNA of any organism consists of unique sequences or genes, the rest is repetitive sequences (repeated tens of thousands to millions of times).
In addition, it
has been found that the DNA and messenger RNA of many genes is interrupted with “spacer” sequences called introns, which have no known function. These introns must be cut out and the RNA molecule spliced before it is transcribed into useful proteins. The connective tissue molecule collagen, the single most abundant protein in nature, is known to have 50 such introns! The emerging complexity of molecular biology and the architecture of the chromosome has not really begun to be assimilated into evolutionary thought.
It has long been hoped that genetics would provide an understanding of the actual genetic substrate on which evolution works but this has not been the case. Attempts to explain evolution by “macromutations” have failed as have the attempts to equate evolution with mere changes in the gene frequencies in populations (population genetics). The evolutionist and population geneticist, Richard Lewontin stated in his book ‘The Genetic Basis of Evolutionary Change’ (1974), that: “It is an irony of evolutionary genetics that, although it is a fusion of Mendelism and Darwinism, it has made no direct contribution to what Darwin obviously saw as the fundamental problem: the origin of species>” (p. 159)
The influential evolutionist, Ernst Mayer, seems to agree with this assessment. In reviewing M.J.D. White’s book ‘Modes of Speciation,’ Mayer commented: “One of White’s rather startling, but I think legitimate findings is how little population genetics has contributed to our understanding of speciation.” (Syst. Zool. 27:478, 1978)
POSTULATED MECHANISMS OF SPECIATION:
Speciation is defined as the production of new, reproductively isolated individuals or populations but even in this very limited sense, there is no agreement on what the mechanism of speciation is. Some have even suggested that there may be as many different mechanisms for speciation as there are species!
The reason for this is simple; although evolutionists are dead certain that speciation has occurred and is now occurring, they can not actually observe it in an unambiguous way. Ernst Mayer has pointed out that this failure to observe speciation has led to limitless speculation: “Speciation, except for polyploidy and some other chromosomal processes is too slow to be observed directly. Therefore, the method of speciation research must consist of an attempt to reconstruct the historical precedents, derive from this reconstruction certain deductive generalizations, and test their validity by proper comparative methods.” “There are nearly always several possible scenarios, and it is not surprising that different authors may differ in the choice of their explanations. Owing to the slowness of the speciation process, it is not possible to study the same individual or population ‘just before’ and ‘just after’ speciation. By necessity there is some arbitrariness in the sequence of events one postulates to have occurred.” (in: Mechanisms of Speciation, pp 1-19)
Ernst Mayer has proposed the widely accepted view that speciation must involve the geographic isolation of a small “founder” population which for some reason might show greater variability than its larger parent population. The bird Tanysiptera galathea, for example, shows little geographical variation on the mainland of New Guinea, but populations on the small islands off the coast are so different they were considered separate species. Other evolutionists are equally certain that speciation can occur without isolation from the main population.
Speciation has been classically attributed to natural selection among the multiple alleles of a species, but this does not really produce anything new as nothing can be selected that does not already exist in the gene pool of the species. Other possible candidates for speciation are major chromosome rearrangements such as translocations, fusions, deletions, inversions and gene duplications. The problem is there is perhaps no way of knowing what genetic events have played a role in initiating a new species.The geneticist and speciation expert M.J.D. White has pointed out that: “Speciation can only be detected post factum, when subsequent genetic changes that have had nothing to do with the original dichotomy may have accumulated. Moreover, to a considerable extent we do not know what we are looking for.” (in Mechanisms of Speciation pp 75-103)
The population biologist Alan Templeton makes the same point: “It is virtually impossible to sort out which differences are actually associated with the process of speciation and which are consequences of evolution subsequent to the speciation process. Hybridization experiments have shown this to be a real problem: Many species differences – morphological, karyotypic, isozyme, etc.- contribute little or nothing to reproductive isolation.” (in; Mechanism of Speciation pp 105-121) With the development of enzyme electrophoresis, a technique that can
simultaneously map out several proteins of an organism, it was hoped that we might actually observe the genetic changes which are the basis of speciation.
Unfortunately, there appears to be little if any direct involvement of the enzyme genes in speciation. Some species that are almost indistinguishable may have quite different proteins (isoenzymes) and very different species may have very similar proteins.Some sibling species of fruit flies can differ at over half of all of their gene loci while the proteins of man and the Rhesus monkey are 99% identical!
Even substantial differences in the arrangement and number of chromosomes may occur among animals of the same species! For example, the mole rat Spalax ehrenbergi, comprises four morphologically indistinguishable populations which differ in chromosome number (52, 54, 58, and 60 chromosomes). They prefer mating with individuals with the same chromosome number but they are still all the same species and there are only 2 allelic substitutions per 100 gene loci.
THE FOSSIL RECORD AND SPECIATION:
It is now a generally accepted fact that species appear suddenly in the fossil record without known ancestors and often disappear just as suddenly from the record.
The fossil record lends no support to the idea that speciation has had anything whatever to do with evolution. Most known fossil species appear to be highly stable entities that remain unchanged, by evolutionary assumptions, for tens of millions of years. Nearly half of the marine bivalve mollusk species in the well represented fossils of the Cenozoic Era are identical in structure to living forms.
Of those not having living
representatives, most are believed by evolutionists to have become extinct rather than having evolved into some other species. The following fossil species comprise at least 50% living species: marine gastropods younger than 3.5 million years old (myo), benthic foraminifera younger than 15 myo, plaktonic foraminifera younger than 10 myo, fresh water fish and terrestrial mammals younger than 7 myo and nearly ALL species of beetles younger than 2 myo.
For plants, fossil species which comprise at least 50% living species include: seed bearing vascular plants younger than 4 myo, marine diatoms younger than 12 myo, bryophytes younger than 10 myo and nearly ALL Miocene and Pliocene species are alive today! These data suggest that for all species of plants and animals, there has been little measurable change in nearly ten billion generations! We may conclude that evolution by “speciation” occurs only in a semantic sense and tells us nothing whatever about how we have come to have lions and horses and chickens and cows and giraffes and dinosaurs etc. etc.
SUGGESTED READING:
Lewontin, R.C., The Genetic Basis of Evolutionary Change, 1974, Columbia
University Press.
Mechanisms of Speciation, Progress in Clinical and Biological Research, 1982,
Alan R. Liss, Inc. New York.
Marsh, Frank L., Variation and Fixity in Nature, 1976, Pacific Press Publishing
Association, Moutain View, CA.
Lester, Lane P. and Bohlin, Raymond G., The Natural limits to Biological
Change, 1984, Zondervan Publishing House, Grand Rapids, MI