John A Davison and the discrete nature and stability of species

Yesterday, Dr. John A. Davison posted a comment presenting his view that:

"Intelligent design is not a matter for debate. It is a mandatory assumption without which nothing in either ontogeny or phylogeny can ever make sense."

As I have declared elsewhere, on reading the writings of John A. Davison I have learned that the role of sexual reproduction is to prevent evolution. I have learned also that the origin of reproduction among living organisms was, in Dr. Davison's words "an independent occurrence..."

Recently, Dr. John A. Davison wrote a brief Essay for ISCID:

Julian Huxley’s Confession (30 Oct. 2005, PDF)

Abstract: The history of any science often reveals aspects of that science that have escaped attention in the intervening years. As someone so wisely put it - ”The one thing we learn from history is that we don’t learn from history.” I present, in this brief essay, one particularly revealing demonstration of that phenomenon, one that is especially significant to the current status of the Darwinian hypothesis.

From the Full Text:

"Where did he [Julian Huxley] get the notion that evolution was finished? This I feel I was able to do [to discover] from a paper by the anti-Darwinian paleontologist Robert Broom. Huxley and Broom had corresponded on the subject as revealed by Broom:

"It is important to remember that Darwin wholeheartedly subscribed to Lyell’s Uniformitarian Doctrine; namely, that the forces we now see shaping the world are the same forces that have operated in the past. While that is what most geologists still accept there is no a priori justification for extending that concept to the living world.... And a few zoologists are beginning to recognize that evolution is slowing down, if not quite stopped. In a letter I had from Professor Julian Huxley only a few months ago he says, ‘I have often thought about your idea of the fading out of evolutionary potency, and though I cannot pretend to agree with some of the philosophical corollaries which you draw from it, I more and more believe that it is of great importance as a fact.’” [Broom, R. (1933) Evolution - Is there intelligence behind it? South African Journal of Science, 30: 1-19]."

I [Dr. Davison] was disappointed to discover that the only reference Huxley made to Broom was in a footnote on page 568: “A small minority of biologists, such as Broom (1933), still feel impelled to invoke ‘spiritual agencies’ to account for progressive evolution, but their number is decreasing as the implications of modern selection theories are grasped.” [Huxley, J. (1942) “Evolution: The Modern Synthesis.” Harper, New York and London.]

[Dr. Davison notes:] The reference to “spiritual agencies” by Broom was his suggestion that there had been a Plan, a word he capitalized.

The reason I [Dr. Davison] have presented this brief essay is to demonstrate that, even from within the Darwinian establishment, grave doubts have surfaced concerning its basic tenets from one of their most prominent spokespersons. I am not surprised Huxley is rarely referenced these days.

Davison's recent comments:

Referring to ontogeny and phylogeny:

"Neither in the one nor in the other is there room for chance." Leo Berg, Nomogenesis, page 134.

When Schindewolf published his "Basic Questions in Paleontology" in 1950, it was perfectly acceptable to say as he did such things as, when comparing the skulls of marsupial and placental saber-toothed cats:

"The similarities of form are present even in such details as the structure of the flange on the lower jaw, DESIGNED TO GUIDE AND PROTECT THE UPPER CANINES." [page 261 in the 1993 English translation. (my [Dr. Davison's] emphasis)].

Dr. Davison affirms:

"I really don't know what else to say except that I enjoy immensely being a part of an intellectual revolution in progress.

It is quite exhilarating."

Let's see other of the vital statements by Dr. Davison:

"Sexual reproduction tends to prevent rather than promote chromosome restructuring."

This provides a reasonable explanation for the stability of fossil species as Julian Huxley realized at the end of his Synthesis.

"Huxley’s conviction that evolution is no longer going on has been completely ignored by the neoDarwinians."

As seen above, Dr. Davison discovered that Broom and Huxley had corresponded on this matter as early as 1933.

"Leo Berg insisted that chance played no role in either ontogeny or phylogeny" [Berg, L. (1969) Nomogenesis; Evolution Determined by Law. M.I.T. Press, Cambridge. (Original Russian edition 1922.)]

We also read in http://www.uvm.edu/~jdavison/davison-manifesto.html

"A sufficient factual body now exists to warrant serious consideration to the proposal that there has been, as Robert Broom had suggested, a teleological origin (plan) for biological information" [and, I must add, its expression].

John A. Davison also declares that there is a

"discrete nature and stability of the vast majority of all species, both recent and fossil," "they were produced by instantaneous all-or-none devices (chromosome restructurings) which, by definition, can have no intermediate states."

http://www.iscid.org/boards/ubb-get_topic-f-6-t-000520.html

http://www.uvm.edu/~jdavison/dpaper.html

"I accept the physiological definition of species. Two forms that can produce a viable hybrid will be considered separate species if that hybrid proves to be sterile."

"... in nature, sexual reproduction seems incapable of proceeding beyond the subspecies. I am unaware of a single instance of the production of a new species through the known agency of sexual reproduction."

http://www.iscid.org/ubbcgi/ultimatebb.cgi?ubb=get_topic;f=6;t=000481

"Sexual reproduction [is] a highly conservative device... a virtual standstill... a function which serves to prevent rather than promote progressive change."

"The capacity of the sexual reproductive mode [is] to fine-tune the genetic makeup."

http://www.uvm.edu/~jdavison/evolution.html

"Sexual reproduction has one great advantage in its capacity to produce virtually unlimited variation within a narrow range. The sexual mode then could be very useful in adapting the organism to minor environmental changes."

"Sexual reproduction is incapable of producing progressive evolutionary change."

http://www.uvm.edu/~jdavison/dpaper.html

"Needless to say, the realization of this prospectus will have a profound effect on the way in which man regards his position in the universe."

http://www.iscid.org/boards/ubb-get_topic-f-6-t-000520.html

"The Darwinians might simply say that the sexual model could also produce chromosome and gene homozygosity through the inbreeding associated with small or insular populations. It is precisely here that their hypothesis fails. For example, the biota of the Galapagos Islands closely resembles that of neighboring Ecuador. Darwin's celebrated finches have all been placed in the genus (or subgenus) Geospiza. Since they are all extremely similar, it is not surprising to learn that they produce spontaneous fertile and genetically fit hybrids" [Grant PR, Grant BR. Genetics and the origin of bird species. Proc Natl Acad Sci U S A. 1997 Jul 22;94(15):7768-75.].

"[Then, Dr. Davison compares dogs, declaring that] in addition to size, great variations in [canine] coat quality, color and temperament have been produced. All of these differences are due to the action of Mendelian genes segregating and recombining in sexual reproduction, with the result that dogs are still able to hybridize freely with wolves. The hybrids are of course fertile which is to say that they are not really [different] species-hybrids at all."

"Thus, by a physiological criterion they [finches] are one species and, as with dogs and goldfish, no significant evolution has really taken place. They too reproduce sexually."

"The standard Darwinian response is that evolution takes too long to be observable, an assumption which renders that proposal untestable."

http://www.uvm.edu/~jdavison/dpaper.html

"The [evolutionarily conceived] horse series shows an increase in size coupled with a decrease in digits. However, this series is not linear so the intermediate organisms cannot be arranged in any certain fashion. Furthermore, they differ from one another in so many independent factors that they must be relegated to separate genera. What we actually observe is the appearance of discrete phenotypes with no evidence of what might be described as missing links. This is exactly what one sees when one observes extant related organisms."

"There are limits to the developments possible, and these limits follow a law (the Law of the Reversion to the Average)."

"I know from my experience that I can develop a plum half an inch long or one two and a half inches long, with every possible length in between, but I am willing to admit that it is hopeless to try to get a plum the size of a pea, or one as big as a grapefruit" [Taken from: Burbank, L. (1939) Partner of Nature. D. Appleton-Century Co., New York; Burbank, L., 1931 The Harvest Of The Years. Houghton Mifflin Co., Boston, New York.]

"The ratio of five to one in the lengths of his plums corresponds to a mass ratio of 125 to 1 (five cubed), which agrees favorably with what man has been able to achieve with dogs (Great Danes versus some of the miniature breeds) or, for example, with the size of the fruits of tomato varieties. Burbank admits the futility of exceeding the limits he indicates and the prospect of speciation apparently never crosses his mind."

http://www.iscid.org/papers/Davison_IsEvolutionFinished_022204.pdf

"Mendelism is of course the genetics associated with sexual reproduction... Luther Burbank and William Bateson each independently questioned the capacity of sexual reproduction to support evolutionary change... These were not mere coincidences but reasoned conclusions reached after a careful consideration of all the facts which were then available.

None of this can be accommodated within the Darwinian model. We owe these men [Burbank, Bateson, etc...] a great debt... i.e. sexual forms are incapable of progressive change. The obvious inference is that sexual reproduction is the "Blind Alley" of evolution."

"Note Bateson's use of the expression blind alley." "Bateson had the insight to recognize and the courage to admit." "Just as William Bateson indicated even before 1900, I too find it amazing how long the Darwinian view has prevailed in the face of an enormous and continually growing body of information with which it cannot possibly be reconciled."

http://www.uvm.edu/~jdavison/dpaper.html

"Subspecies are actually, therefore, neither incipient species nor models for the origin of species. They are more or less diversified blind alleys within the species"

"The male-determining (Y) chromosomes lack, both quantitatively and qualitatively, the semblance one would expect had the four genera [man, chimpanzee, gorilla and orangutan] evolved through sexual reproduction. Other differences include alterations in chromosome ends or telomeres as well as variations in the position of nucleolar organizers..." [Davison on a critical review of: Yunis JJ, Prakash O. The origin of man: a chromosomal pictorial legacy. Science. 1982 Mar 19;215(4539):1525-30.]

http://www.uvm.edu/~jdavison/davison-manifesto.htm

"It has yet to be demonstrated that any creature reproducing by obligatory sexual means is capable of evolution beyond the generic level. Since 1984 no response to that challenge has been forthcoming and so I repeat the proposition. I hope the present paper will serve to stimulate a lively response from the community of evolutionists."

http://www.uvm.edu/~jdavison/evolution.html

"It has yet to be demonstrated that any diploid organism, reproducing by obligatory sexual means, is capable of exceeding the subspecies level..." "I place the burden of proof on the Darwinians by challenging them to present karyotypic, genetic, taxonomic, fossil, or any other kind of evidence indicating that true species, genera, families, or any of the higher taxonomic categories have ever been produced or can now be produced through the agency of sexual reproduction. I, in general agreement with [Michael J.D.] White, can find nothing in support of that proposition." [Davison on commenting, White, M.J.D. (1973) Animal Cytology and Evolution. Comstock Publ. Co., Ithaca, New York; and Davison, JA (1984) J. Theor.Biol. 111: 725-735.]

http://www.uvm.edu/~jdavison/davison-manifesto.html

"I agree with Michael J.D. White... there is no compelling evidence that point (base pair) mutations have ever played a role in evolution beyond the production of varieties or subspecies. Quite the contrary, all expermental attempts with selection for such mutations has met with not only failure but with a decrease in general fitness... The time is long past due to consider some alternatives to the Darwinian model" [Posted by nosivad (Member # 767) on 14. April 2004, 07:34]

http://www.iscid.org/boards/ubb-get_topic-f-6-t-000488-p-5.html

"Like differentiation, ecological succession and growth, phylogeny has been, in my opinion, a self-limiting process in which sexual reproduction has served to terminate and stabilize the creative sequence. This view demands only the original actions of an incomprehensibly intelligent creator" [Posted by nosivad (Member # 767) on 20. April 2004, 08:01]

http://www.iscid.org/boards/ubb-get_topic-f-6-t-000488-p-6.html

"Why might some insist that evolution is still in progress? I propose it is in large part due to the acceptance of authority. For centuries, Aristotelian physics was accepted because it made intuitive sense that the heavier an object was, the faster it would fall... Darwin and Wallace unhesitatingly accepted the authority of Lyell and his doctrine of Uniformitarianism."

"Is sexual reproduction incapable of supporting evolutionary change?" [a question raised by Dr. Davison, who then proceeds to answer it by his studies on the evidence.]

The Russian cytologist N.N. Vorontsov was one of the first to call attention to the independence in sex determination: i.e., "an independent occurrence of the XX-XY system in Melandrium as well as in many Insects and Mammals, whereas the ZW-ZZ system evolved independently in Trichoptera, Lepidoptera, Serpentes and in Aves [Birds]. Against the background of these facts it is unclear whether the male species of different groups are homologous to each other or not; they appear to be nonhomologous." [Vorontsov, N. N., 1973 The Evolution Of The Sex Chromosomes. In: Cytotaxonomy and Vertebrate Evolution, edit. A. B. Chiarelli and E. Capanna. p. 646. Academic Press, New York. See page 646]

http://www.uvm.edu/~jdavison/evolution.html

"Notice specially Vorontsov's indication:

"Males seem to be nonhomologous, a conclusion that would, by definition, demand that they were independently produced and accordingly could not be involved in a macroevolutionary continuum."

http://www.uvm.edu/~jdavison/davison-manifesto.htm

"Vorontsov says:

"Just as the transition from isogamy to anisogamy and to oogamy took place independently of each other in the various phyla of plants so the formation of mechanisms of the cytogenetical sex determination with differentiated heterochromosomes follows the same pattern in various kingdoms and phyla and results in an independent occurrence of the XX-XY system [Mammals]" and "the ZW-ZZ system [Birds]."

http://www.uvm.edu/~jdavison/evolution.html

"In addition to the devices mentioned by Vorontsov, other independent mechanisms include, "In the social insects, the female is diploid, the male haploid, a situation that also occurs in certain rotifers. In addition to these chromosomal mechanisms, the temperature during sensitive embryonic stages can serve to determine the sex as in some turtles and crocodilians. Sex reversal is common in certain animals as well as other forms of sex determination such as the age of the eggs when fertilized. This huge and varied literature has been reviewed by Bull [Bull, J.J. (1983) Evolution of Sex Determining Mechanisms. Benjamin Cummings, Menlo Park.] This is hardly the sort of situation one would anticipate if sexual reproduction were a requirement for evolutionary change."

"Any theory of evolution must recognize and incorporate nonhomology when that becomes evident. It is to the credit of Vorontsov that he did so when describing the various sex determining systems which have evolved. They have indeed evolved independently and accordingly are by definition nonhomologous. Another example of nonhomology which correlates beautifully with the various sex determining devices which have evolved is demonstrated by the origins of the germ cells in contemporary vertebrates."

http://www.uvm.edu/~jdavison/dpaper.html

"Not only are the cytological mechanisms of sex determination often nonhomologous but the expression of the sexual phenotype may also be nonhomologous. For example, both Drosophila and all mammals have a heteromorphic (different form) XY male - XX female system. However, sexual differentiation is mediated at the local cellular level in Drosophila but by means of hormones in all mammals. It is obvious that the two systems are in no sense related but independent."

"One of the hitherto most baffling features of vertebrate ontogeny is offered by the origin of those cells (oogonia and spermatogonia) destined to become the eggs and sperm."

"I regard this conclusion as inescapable."

http://www.uvm.edu/~jdavison/davison-manifesto.htm

"All known mammals have male heterogamety with the familiar XY male and XX female. By contrast, all birds are the opposite with ZW females and ZZ males." And a similar dichotomy "within the amphibia with most urodeles (newts and salamanders) like birds and all anurans (frogs and toads) except Xenopus like mammals. In reptiles examples of both kinds occur as well as temperature determination of sex in certain turtles and crocodilians."

"Among the arthropods similar differences prevail. Diptera generally have heterogametic males while Lepidoptera are like birds and urodeles with heterogametic females. In the social insects a haplo-diplo (male-female) system operates. In certain parasitic forms even the size of the host can determine the sex of the parasite. The literature is well reviewed in Bull's (Bull 1983, ref. given above) book significantly titled "Evolution of Sex Determining Mechanisms".

"The vertebrate gonad develops from portions of the urogenital ridge, a bipartite structure consisting of an outer cortex and inner medulla. The gonadal cortex develops into the ovary, the medulla into the testis. Oddly the vertebrate gonad is a sterile organ completely incapable of functioning as a germinal epithelium. During embryonic development the gonad receives, by a process of invasion, presumptive germ cells from extra-gonadal sources. Gonads failing to receive these cells remain sterile, while those receiving presumptive germ cells differentiate with the sex of the host organ not that of the donor cells. Thus the gonad proper is clearly a part of what Weismann called the somatoplasm."

"The important point to make here is that the sources as well as the means of induction and modes of reaching the gonad vary in nonhomologous fashion from vertebrate group to group in a manner which remarkably parallels the equally nonhomologous modes of sex determination."

"In mammals, including man, the presumptive germ cells are first seen in the region of the allantois corresponding roughly to the position of the urinary bladder in the adult. From here they migrate anteriorly and laterally to enter the embryonic gonad. In birds the future germ cells originate outside the embryonic axis in the extra-embryonic endoderm consisting of the so-called germinal crescent anterior and lateral to the head. From here they enter the vitelline circulation and after a period in the circulatory system invade the gonad after first passing through the walls of the venous circulation."

http://www.uvm.edu/~jdavison/evolution.html

It is in the amphibia that the most dramatic differences are manifest in the origin of the germ cells. From their monograph Nieuwkoop and Sutasurya write (see below):

"When comparing PGC formation in the urodeles with that in the anurans, one is unavoidably led to the conclusion that not only do the PGCs originate from two different sites in the two groups, but that there are moreover two fundamentally different mechanisms at work... In the anurans all the PGCs originate from the endodermal moiety of the egg in the vicinity of the vegetal pole, whereas in the urodeles they arise from the animal 'ectodermal' moiety, more particularly the presumptive lateral plate mesoderm in the ventral to ventro-lateral equatorial region. In the anurans all the descriptive and experimental evidence pleads in favor of the predetermined nature of the PGCs, based on the presence of a germ-cell-specific sytoplasmic component, the germinal plasm, which is present in the embryo from the very beginning of development. In constrast, in the urodeles the PGCs develop strictly epigenetically from common, totipotent cells of the animal moiety under the inductive influence of the ventral yolk endoderm" [Nieuwkoop, P.D. & Sutasurya, L.A. (1979) Primordial Germ Cells in the Chordates. Cambridge Univ. Press, Cambridge.]

"Note the clear correlations between nonhomologous modes of sex determination and equally nonhomologous methods and sources for germ cell formation. As I have indicated elsewhere any theory of evolution must include in its postulates these fundamental differences (Davison 1984, see above). As well as I can determine the neo-Lamarckians, the neo-Darwinians, and the Creationists all fail even to acknowledge the existence of this experimental and descriptive literature, not to mention its significance for their particular views. In that respect the Creationists are missing an opportunity for their case since nonhomology means separate origin, which prima facie might be interpreted to mean special creation."

http://www.uvm.edu/~jdavison/evolution.html

"First, since the definitive sex cells of the various vertebrate groups cannot be homologized, they cannot be considered as ancestral cell lineages. Rather they are secondary or derived lineages correlated in their origins with the equally independent and nonhomologous invention of sexual reproduction."

"The actual facts are as follows. In birds the cells destined to become the germ cells first appear in the extra-embryonic endoderm (germinal crescent) anterior to the head of the developing embryo. Incidentally, this region has no homologue in the hatched bird as the extra-embryonic endoderm is, by definition, resorbed as nutrient for the developing chick. From there the presumptive germ cells enter the circulatory system and, after a period of time in the bloodstream, penetrate the walls of the venous circulation and invade the gonad where they differentiate into the definitive gametes. In mammals the presumptive germ cells first appear in the endoderm of the allantois, a structure destined to become the urinary bladder of the adult. From here they migrate in amoeboid fashion anteriorly and laterally to reach the gonad where they complete their differentiation. Thus, there is no way that the reproductive cells of mammals can be homologized with those of birds as they originate from opposite ends of the embryonic axis and reach the gonads by completely different means."

"Similarly, the eggs and sperm of the Anura (frogs and toads) arise in an entirely different way than do those of the Urodela (salamanders and newts). Staining methods reveal that in frogs, the cells destined to become the germ cells result from the presence of preformed granules near the vegetal pole of the unfertilized egg, a region destined to become part of the endoderm. From there they move first dorsally and then laterally to enter the embryonic gonads which are mesodermal structures. In salamanders the presumptive germ cells first appear in the mesoderm as a result of the inductive action of the underlying endoderm on the lateral plate mesoderm. From there they migrate medially to invade the embryonic gonads."

"Thus the germ cells of the Anura and the Urodela do not even arise from the same germ layer! In short, there is not a scintilla of evidence to support the notion of germ cell continuity. The details of these differences have been discussed elsewhere (Davison 1984). Also, the vertebrate gonad is a sterile organ unable to produce germ cells from its own epithelium (Nieuwkoop and Sutasurya 1979). Instead, the testis or ovary receives its complement of eggs or sperm by a process of invasion from extragonadal sources early in development. Since the sources and modes of invasion are not homologous from group to group, the continuity of the germ plasm is a myth."

http://www.arn.org/boards/ubb-get_topic-f-13-t-000857-p-2.html

"Note that these nonhomologies correlate favorably with the nonhomologous devices that serve to determine the sex differences…"

"Repeating the simple facts again: "There is no way that the reproductive cells of mammals can be homologized with those of birds. Similarly, the eggs and sperm of frogs arise in an entirely different way than do those of salamanders and accordingly cannot be assumed to exhibit homology. In short, there is not a scintilla of evidence to support the notion of the continuity of the germ plasm" [between the different real species.]

"These nonhomologies correlate beautifully with the equally nonhomologous devices that determine the sexes."

"This remarkable conclusion is of course totally incompatible with the neo-Darwinian concept of the evolutionary process."

"Understanding the nature of sexual reproduction and the manner in which eggs and sperm are produced:

"In all diploid animals and plants the chromosomes occur in pairs. One member of each pair comes from one parent, the other from the other parent. Thus, each egg or sperm must have only one of each kind of chromosome, a condition known as haploidy. The process by which this reduction takes place is known as meiosis or chromosome reduction... If one were to imagine the simplest way that chromosome reduction could take place it might be as follows. The chromosomes would align in pairs and a single division would take the chromosome number from diploid to haploid. Not a single living creature undergoes meiosis in this way. Instead, each chromosome is duplicated taking the chromosome number from diploid to tetraploid. Then while they are in alignment (synapsis) a very important step occurs. Breaks occur in some of the chromosomes and exchanges occur between the original pairs of chromosomes a phenomenon known as crossing over. Following this event, the chromosomes undergo the first meiotic division returning the chromosome number from tetraploid to diploid... The two originally identical chromosomes (known as sister strands) always remain together. Note that this first meiotic division is a perfectly valid form of diploid reproduction... meiosis involves two steps."

http://www.uvm.edu/~jdavison/dpaper.html

Some References:

Davison JA. A Prescribed Evolutionary Hypothesis. Riv Biol. 2005 Jan-Apr;98(1):155-65. Review.

Davison, John A. An Evolutionary Manifesto: A New Hypothesis For Organic Change (2003). PCID Journal.

Davison, John A. Evolution as a Self-limiting Process (1998). Rivista di Biologia (Biology Forum), 91:2 199-220.

Davison, John A. The Blind Alley: Its Significance for Evolutionary Theory (1993). Rivista di Biologia (Biology Forum), 86:101-110.

Davison, John A. The Case for Instant Evolution (2004). ISCID Brainstorms.

Davison, John A. Is Evolution Finished? (2004). ISCID Brainstorms. In PubMed.

Davison, JA (1984) Semi-meiosis as an Evolutionary Mechanism. J. Theor.Biol. 111: 725-735.

Davison JA (2004) ISCID Brainstorms and other boards: http://www.iscid.org/boards/ubb-get_topic-f-6-t-000488-p-5.html ,

http://www.iscid.org/boards/ubb-get_topic-f-6-t-000488-p-6.html ,

http://www.arn.org/boards/ubb-get_topic-f-13-t-000857-p-2.html ,

http://www.arn.org/boards/ubb-get_topic-f-13-t-000716-p-5.html ,

http://www.arn.org/boards/ubb-get_topic-f-1-t-001152.html

The Non-Darwinian Mechanism of Sexual Reproduction (Research guidelines provided by John A. Davison)

Appendix:

Other Species-Specific Sexual Issues.

Bookbinder LH, Cheng A, Bleil JD. Tissue- and species-specific expression of sp56, a mouse sperm fertilization protein. Science. 1995 Jul 7;269(5220):86-9.
[From the Scripps Research Institute, San Diego, California]

"Sperm-egg recognition and binding in mammals is largely species-specific"
"sp56 expression is restricted to mouse spermatids and the presence or absence of sp56 on sperm from different species accounts for species specificity of sperm-egg recognition in mice."
"Suggesting that molecular recognition between the sperm head plasma membrane and the Zona Pelludica (ZP) surface involves different molecules in different species… Mouse and hamster sperm, which bind to the ZP of mouse eggs, contained sp56. However, sp56 was not detected in guinea pig.sperm or human sperm, which do not bind to mouse egg ZP… If sp56 mediates sperm-egg recognition in mouse, its presence or absence accounts for the species specificity of that event."

It was performed immunological and biochemical identification of sp56 and also the identification of its transcript.

Some Appendix References:

1-) Schmell ED, Gulyas BJ. Mammalian sperm-egg recognition and binding in vitro. I. Specificity of sperm interactions with live and fixed eggs in homologous and heterologous inseminations of hamster, mouse, and guinea pig oocytes. Biol Reprod. 1980 Dec;23(5):1075-85.

2-) Moller CC, Bleil JD, Kinloch RA, Wassarman PM. Structural and functional relationships between mouse and hamster zona pellucida glycoproteins. Dev Biol. 1990 Feb;137(2):276-86.
" Like mouse ZP2, hZP2 undergoes limited proteolysis following artificial activation of hamster eggs in vitro. Results of in vitro assays employing intact eggs and isolated zonae pellucidae demonstrate that hamster eggs possess a ZP2-proteinase which has a substrate specificity similar to that of the mouse enzyme."

3-) Inoue M, Wolf DP. Sperm binding characteristics of the murine zona pellucida. Biol Reprod. 1975 Oct;13(3):340-6 [see also, Inoue M, Wolf DP. Fertilization-associated changes in the murine zona pellucida: a time sequence study. Biol Reprod. 1975 Dec;13(5):546-51.]

4-) Bedford JM, Cross NL. Normal penetration of rabbit spermatozoa through a trypsin- and acrosin-resistant zona pellucida. J Reprod Fertil. 1978 Nov;54(2):385-92 [see also, Moore HD, Bedford JM. An in vivo analysis of factors influencing the fertilization of hamster eggs. Biol Reprod. 1978 Nov;19(4):879-85; Moore HD, Bedford JM. Ultrastructure of the equatorial segment of hamster spermatozoa during penetration of oocytes. J Ultrastruct Res. 1978 Feb;62(2):110-7; Bedford JM, Anat. Rec. 188:477, 1978]

5) Lambert H. Role of sperm-surface glycoproteins in gamete recognition in two mouse species. J Reprod Fertil. 1984 Jan;70(1):281-4.

6) Cheng A, Le T, Palacios M, Bookbinder LH, Wassarman PM, Suzuki F, Bleil JD. Sperm-egg recognition in the mouse: characterization of sp56, a sperm protein having specific affinity for ZP3. J Cell Biol. 1994 May;125(4):867-78.
"Immunohistochemical and immunoblotting studies, using monoclonal antibodies, demonstrated that sp56 is a peripheral membrane protein located on the outer surface of the sperm head plasma membrane, precisely where sperm bind ZP3." "Collectively, these results suggest that sp56 may be the sperm protein responsible for sperm-egg recognition in the mouse."

7) Suzuki-Toyota F, Maekawa M, Cheng A, Bleil JD. Immuno-colloidal gold labeled surface replica, and its application to detect sp56, the egg recognition and binding protein, on the mouse spermatozoon. J Electron Microsc (Tokyo). 1995 Jun;44(3):135-9.

8) Bleil JD, Wassarman PM. Identification of a ZP3-binding protein on acrosome-intact mouse sperm by photoaffinity crosslinking. Proc Natl Acad Sci U S A. 1990 Jul;87(14):5563-7.
"These and other findings suggest that this protein may be a "ZP3-binding protein" that, together with the sperm receptor, supports species-specific binding of mouse sperm to unfertilized eggs."

9) Bleil JD, Wassarman PM. Mammalian sperm-egg interaction: identification of a glycoprotein in mouse egg zonae pellucidae possessing receptor activity for sperm. Cell. 1980 Jul;20(3):873-82.

10) Wassarman PM. Sperm receptors and fertilization in mammals. Mt Sinai J Med. 2002 May;69(3):148-55.
"During fertilization in mammals, sperm must first bind in a species-specific manner to the egg s thick extracellular coat, the zona pellucida."

11) Wassarman PM, Litscher ES. Towards the molecular basis of sperm and egg interaction during mammalian fertilization. Cells Tissues Organs. 2001;168(1-2):36-45.
"mammalian fertilization is a carbohydrate-mediated event. It is possible that changes in the structure of these oligosaccharides (e.g., composition, sequence, linkages, modifications, etc.) could account for species-specific binding of sperm to eggs."

12) Wassarman PM. Fertilization in animals. Dev Genet. 1999;25(2):83-6.
"species-specific binding of sperm to eggs"

13) Litscher ES, Wassarman PM. Recombinant hamster sperm receptors that exhibit species-specific binding to sperm. Zygote. 1996 Aug;4(3):229-36.
"Unlike hamster egg hZP3, which binds to both mouse and hamster sperm, EC-hZP3 and CHO-hZP3 exhibits species-specific binding to hamster sperm and induce hamster sperm, but not mouse sperm, to undergo the acrosome reaction in vitro... recombinant forms of mammalian sperm receptors may be useful in assessing the molecular basis of species-specific fertilisation in mammals."

14) Wassarman PM. Profile of a mammalian sperm receptor. Development. 1990 Jan;108(1):1-17.
"Complementary molecules on the surface of eggs and sperm are responsible for species-specific interactions between gametes during fertilization in both plants and animals... ZP3 gene expression is an example of oocyte-specific and, therefore, sex-specific gene expression during mammalian development... unique nature, highly restricted expression, and multiple roles of ZP3..."

15) Kinloch RA, Wassarman PM. Profile of a mammalian sperm receptor gene. New Biol. 1989 Dec;1(3):232-8.
"ZP3 regulates the initial species-specific interactions between male and female mouse gametes."

16) Wassarman PM. The biology and chemistry of fertilization. Science. 1987 Jan 30;235(4788):553-60.
"In both mammals and nonmammals, the pathway that leads to fusion of an egg with a single sperm consists of many steps that occur in a compulsory order. These steps include species-specific cellular recognition."

17) Wassarman PM, Bleil JD, Florman HM, Greve JM, Roller RJ, Salzmann GS. Nature of the mouse egg's receptor for sperm. Adv Exp Med Biol. 1986;207:55-77.
"sperm must bind to the outer margin of the zona pellucida. Such binding is mediated in a relatively species-specific manner by "sperm receptors" in the zona pellucida"

18) Keichline LD, Wassarman PM. Developmental study of the structure of sea urchin embryo and sperm chromatin using micrococcal nuclease. Biochim Biophys Acta. 1977 Mar 2;475(1):139-51.
"…the oligomers are nearly exact multiples of the respective monomers. These results are discussed in relation to those studies which have shown that the histone complement of the sea urchin embryo and sperm changes during development."