Quotes from William Bateson on a second level of genetic information of importance for speciation

"Though some degree of sterility on crossing is only one of the diverse properties which may be associated with Specific difference [differentiation of species], the relation of such sterility to Mendelian phenomena must be a subject of careful enquiry. ...The sterility of certain crosses is merely an indication that they cannot divide up the [parental] characters among their gametes. If the parental characters, however dissimilar, can be split up [segregated], the gametes can be formed, and the inability to form gametes may mean that the process of resolution [separation of characters] cannot be carried out. ...

Has a given organism a fixed number of unit-characters? Can we rightly conceive of the whole organism as composed of such unit characters, or is there some residue -- a basis -- upon which the unit characters are imposed?... We are thus brought to face the further question of the bearing of Mendelian facts on the nature of species. The conception of Species, however we may formulate it, can hardly be supposed to attach to allelomorphic or analytical varieties [characters associated with conventional Mendelian genes]. We may be driven to conceive "Species" as a phenomenon belonging to that "residue"... ."

"Cytological appearances: sterility

...the relation of Mendelian observations to the facts of cell division. Nevertheless it should be remarked that all that has been observed by cytologists is consistent with the results of experimental genetics. The recognition of a definite differentiation among the chromosomes (see especially Sutton [1902; Biol. Bull. 4, 24]) is probably an important advance, though until we can positively recognize characters in the zygote as associated with some visible cytological elements we must be cautious in forming positive conclusions as to the relation of cytological appearances to the phenomena of heredity.

Such an observation has however been lately made by E. B. Wilson ([1906; J. Exp. Zoology 3, no 1]) who has found evidence of a visible dimorphism among the sperm cells of certain insects, and has shown that this dimorphism corresponds with differences existing between the somatic cells of the males and females of these species. ...

There is still no positive proof that segregation occurs at the reduction division, but all the facts known point to that conclusion. Indeed we can scarcely doubt that this is the critical moment. Investigations of sterile forms (Guyer [Chicago 1990 dissertation]; Gregory [1905. Proc. Camb. Phil. Soc. 13, 148]) show that it is often at this division that abnormality begins.

Nevertheless I am not yet convinced that segregation is exclusively confined to that division ... in the somatic cell divisions similar processes may be concerned. That segregation precisely similar to that which occurs among gametes may take place in somatic divisions is indeed proved by the existence of bud-sports. The appearance of a glabrous Nectarine on a Peach tree or of a white flower on a red-flowered plant is unquestionably due to segregation, and it is interesting to observe that the characters which segregate in these "sports" are often those which we know to segregate in gametogenesis. Such facts raise the fundamental question whether in the normal process of somatic differentiation, segregations of a similar nature may not occur ... . [includes phenomena now known as "loss of heterozygosity" or "gain of homozygosity" due to gene conversion (non-reciprocal recombination)]

The Relation of Mendelian Segregation to Specific [Species] Distinctions.

Mendelian segregation proves the unity of characters. Is it a sound deduction that specific differences [differences fundamental to the differentiation of species] come into existence by the addition or elimination of such character units? ... It is scarcely necessary to insist that plenty of the characters which are now known to segregate would be far more than sufficient to constitute specific differences in the eyes of most systematists ... . But this is not enough. We must eventually go further; and ... we must ask whether the results of ... investigation will show

first that certain kinds of differences segregate and that certain other kinds to not segregate; and
secondly whether we shall then recognize that it is to the non-segregating that the conception of species attaches with greater propriety. ...

We may indeed, as I have said elsewhere ([Reports to the Evolution Committee. 1902]), be driven to conceive specific difference as a property of the residue or basis upon which the allelomorphic characters are implanted; but it is not easy to suppose that the features, breadth of leaves, and length of flowering stem -- named by de Vries as non-splitting [segregating] characters in Lychnis -- are of this fundamental nature. ...

[dated] August 1906."

William and Beatrice with his collaborator and sister-in-law Florence Durham

William, Beatrice and his collaborator and sister-in-law Florence Durham.
First International Congress of Genetics 1906

[For one way of looking at implanting on a base or residue, see the figures of Goldschmidt (1917) as reproduced by Richmond and Dietrich (2002; Genetics 477-482.]

"Possible Limits to Recombination.

It will probably occur to many that there are limits to these possibilities of transference [of conventional genetic characters], and so undoubtedly there are. The detection of these limits is one of the more important tasks still awaiting us. Though on this head [under this heading] little can yet be asserted with confidence, it is likely that such limitations are constituted in two distinct ways:

First, from all we know of the capacities of animals and plants we must anticipate that some characters are incompatible in the same individual. For example, in cattle the highest milk-production is not to be found in the breeds which make the best beef. Meat-production and milk-production are to some extent alternative and can only be combined by compromising one quality or the other. That such an alternative distribution is merely the result of allelomorphism seems on the whole unlikely, though certainly not impossible. ... (Page 79: It will be enough to regard those factors which prevent others from manifesting their effects as higher, and the concealed factors as lower. In accordance with this suggestion, the terms epistatic and hypostatic may conveniently be introduced.).
Then again we must surely expect that these transferable characters [conventional genic characters] are attached to, implanted upon, some basal organization, and the attributes or powers which collectively form that residue may perhaps be distinguishable from the transferable [conventional genetic] qualities. The detection of the limits thus set upon the interchangeability of characters would be a discovery of high importance and would have a most direct bearing on the problem of the ultimate nature of Species."[page 73]

(Full text of 1914 Address proposing genetic information as a 'phenomenon of arrangement', which we can now interpret as a sequence of bases in DNA.) (Click Here)

"...Left with the conviction that some part of the chain of reasoning is missing. ... [Genetic] analysis has revealed hosts of transferable characters [genes]. Their combinations suffice to supply an abundance of [pheno]types which might pass for new species, and certainly would be so classed if they were met with in nature. Yet critically tested [by hybridizing], we find that they are not distinct species and we have not reason to suppose that any accumulation of characters of the same order [transferable characters amenable to conventional genetic analysis] would cumulate in the production of distinct species. ... Specific difference [that which is responsible for speciation] therefore must be regarded as probably attached to the base upon which these transferables are implanted, of which we know absolutely nothing at all."

Bateson frequently refers to the work of Michael F. Guyer (1874-1959; see Guyer webpage (Click Here)). Bungener and Buscaglia (2003; Hist. Phil. Life. Sci 25, 27-50) reveal that there is material in Guyer's 1900 thesis that is not in the 1902 paper. In particular, they note from page 51 of the thesis that Guyer:

>"was convinced of the role of cytoplasm in the hereditary transmission. In his opinion, the cytoplasm brought a 'general substratum' providing the general characteristics of the species on which were superimposed the specific characters of the individual conveyed by the chromatin."

This idea of individual characters (i.e. those due to Mendelian genes) being superimposed upon a cytoplasmic substratum where species characteristics were located, may be a clue to (a) why Bateson was convinced of the existence of a non-genic hereditary element involved in speciation, and (b) why Bateson thought this might not necessarily be chromosomally located.

An interest of the following interchange between Bateson and his critic C. R. Crowther, is the "sword and scabbard" analogy, which can now be extrapolated to the stereospecific pairing between DNA bases in homologous chromosomes. Crowther points out that the requirements for cooperation, which, if it failed, would produce a inviable hybrid, should be less stringent than the requirements for meoitic pairing ("conjugation"), which, if it failed, would produce a sterile hybrid. Crowther imagines that the latter failure, due to differences between the homologs, would be the result of: "a gradual modification, spread over a length of time, and involving many chromosomes".

Letter to Nature (1922) 109, 777.

"No one can have read without interest Dr. Bateson's admirable address on evolution published in Nature of April 29. While Dr. Bateson's reputation is justly high and his views necessarily command respect, it must be admitted that some of his arguments are very difficult to follow. When, for example, he says that "the conclusion that species are a product of a summation of variations, ignored the chief attribute of species, that the product of their crosses is frequently sterile in greater or less degree," I am frankly puzzled. The proposition is certainly not self-evident.

If a sword and its scabbard are bent in different directions, it will happen sooner or later that the sword cannot be inserted, and the result will be the same whether the bending be effected by a single blow, or whether it be, in Dr. Bateson's words, "a product of a summation of variations". Is this illustration inapt? The sword and its scabbard are the homologous chromosomes. These presumably have to cooperate to produce the somatic cell of the hybrid, and their cooperation might be expected to require a certain resemblance, but for the production of sexual cells they must do more, they must conjugate [chromosomes must pair]; and for conjugation it is surely reasonable to suppose that a much more intimate resemblance would be needed.

We might, therefore, expect, on purely theoretical grounds, that as species and genera gradually diverged, it would be increasingly difficult to breed a hybrid between them; but that, even while a hybrid could still be produced [e.g. a mule], a fertile hybrid would be difficult or impossible, since the cells of the germ-track would fail to surmount the meiotic reduction stage, when the homologous chromosomes conjugate. This is exactly what happens: the cells [of the hybrid] go to pieces in the meiotic phase.

It would even seem that the argument is exactly contrary to Dr. Bateson's statement of it: it seems easier to imagine sterility arising from a gradual modification, spread over a length of time, and involving many chromosomes, than from the half-monstrous variations chiefly studied by Dr. Bateson and his school, variations which appear to affect only a few chromomeres, and those by loss along.

Now I certainly cannot pretend to much or special knowledge, either in genetics or cytology. But I would ask Dr. Bateson in all humility whether there is any difficulty involved in this simple solution of his problem. Very likely there is, but he does not indicate it."

C. R. Crowther. 2 Mutley Park Villas, Plymouth.

Reply: "Interspecific Sterility" Nature 110, 76

"...My address ... I directed once more the attention of naturalists to the fact that we still await the production of an indubitably sterile hybrid from completely fertile parents which have arisen under critical observation from a single common origin. So far as our knowledge goes, all the domesticated races -- for example, of dogs, of pigeons, of fowls among animals; and of cabbages, of peas, of Primula sinensis, and many more among plants -- when inter-crossed among themselves never produce this sterility in their mongrels, though the races are often distinct enough to pass as species [using anatomical criteria]. But if we begin crossing natural species, even those which on our reckoning must be very closely allied, we constantly find either that they will not interbreed, or that, if they can be crossed, the result is more or less sterile. ...

... Mr. Crowther (Nature June 17th, p. 777) mistakes my meaning. It is, as he says, not difficult to "imagine" interspecific sterility produced by a gradual (or sudden) modification. That [type of] sterility [between members of different species] may quite reasonably be supposed to be due to the inability of certain chromosomes to conjugate, and Mr. Crowther's simile of the sword and the scabbard may serve to depict the sort of thing we might expect to happen. But the difficulty is that we have never seen it happen to swords and scabbards which we know to have belonged originally to each other. On the contrary, they seem always to fit each other [no hybrid sterility], whatever diversities [genic differences] they may have acquired [i.e. hereditary differences sufficient to cause initial phenotypic differences are insufficient to separate sword from scabbard]."

W. Bateson. July 2, 1922.

From William Bateson FRS, Naturalist. His Essays and Addresses. Cambridge University Press, 1928. p. 406-408.

"If we now have to recognize that the transferable [genic] characters do not culminate in specific distinctions [cause the origin of species], the acknowledgement will not come from us alone. The old belief of systematists that real species differ from each other in some way not attainable by summation of varietal [genic] characters is no longer contestable, and we know now upon what to concentrate.

It is no occasion for dismay. We have not to go back very far. We do not understand specific differences [speciation], nor can we account for the adaptive mechanisms. Was it to be expected that we should? Biology is scarcely a century old, and its intensive study is of yesterday. There is plenty of time ahead.

The identification of the transferable characters and their linkages has led to a further discovery of the greatest ... brilliancy, which must have consequences as yet unestimable. Morgan and his colleagues have ... proved that some, probably all, of this group of characters are determined by elements transmitted in or attached to the chromosomes....

[However] We have determined the transferable [genic] characters as one group, and we no longer confound them with the essential elements conferring specificity [speciation]. Segregation [of genic characters] is of course often seen in species crosses, but as to the behaviour of these critical elements [those conferring species specificity] we know as yet very little."

"In 1922 I had the honour of delivering the Leidy Memorial Lecture at Philadelphia. The substance of that address is embodied in the following paper. I was reluctant to publish it immediately for several reasons. The evidence to which I appealed had not been fully tested. Some also might be disposed to set aside the phenomena adduced, on the ground that they are exceptional and of small immediate significance pending the determination of broader principles.

Experience has meanwhile provided confirmation where it was required, and several of the classes of segregation which might formerly be held peculiar or anomolous, have been demonstrated in such abundance that no survey of genetical physiology can disregard them. In so far, moreover, as I was concerned with principle, I wished for opportunities of hearing the criticism of other geneticists holding different opinions; but after such debates I have learned nothing which appears to dispose of the views to which I inclined.

The growth of genetical science has been surprisingly rapid. To those who have not forgotten the period of stagnation which so long continued, such an activity can only be a source of satisfaction, as implying zeal both in observation and in invention. We do well, however, to remember that that long spell of dullness from which we were so lately emancipated, ensued as the direct consequence of a too facile acquiescence in impermanent doctrines. Curiosity was too easily allayed. We are in no such danger yet, but the following pages may at least serve as reminder that, even as regards the outline of genetical principles, finality has not been obtained.

... Having in view the various facts and considerations here enumerated, I think we shall do genetical science no disservice if we postpone acceptance of the chromosome theory in its many extensions and implications. Let us distinguish fact from hypothesis. It has been proved that, especially in animals, certain transferable [genic] characters have a direct association with particular chromosomes. Though made in a restricted field this is a very extraordinary and most encouraging advance.

Nevertheless, the hope that it may be safely extended into a comprehensive theory of heredity seems to me ill-founded, and I can scarcely suppose that on a wide survey of genetical facts, especially those so commonly witnessed among plants, such an expectation would be entertained. For the phenomena to which the simple chromosome theory is inapplicable, save by the invocation of a train of subordinate hypotheses, have been there met with continually, as even our brief experience of some fifteen years has abundantly demonstrated.

Through all this work, with ever increasing certainty, the conviction has grown that the problem of heredity and variation is intimately connected with that of somatic differentiation, and that in an analysis of the interrelations of the two manifestations of cellular diversity lies the best prospect of success. Pending that analysis, the chromosome theory, though providing much that is certainly true and of immense value, has fallen short of the essential discovery."

For sporadic sterility Mendelian (3:1) ratios are followed. For non-sporadic sterility, all (or most) offspring are sterile.

Thus, sporadic sterility referred to genes, whereas non-sporadic sterility referred to the "base" or "residue" upon which the genes were considered to be implanted. It is proposed by the author of these pages that the residue can be equated with the "accent" of DNA - the percentage (G + C) in DNA. For more, please see:

This page was established circa 2000 and last edited 12 January 2014 by Donald Forsdyke