Kenneth B. Cumming, Ph.D.
IMPACT
No. 215, May 1991

Notice that the definitions of species as used above hinge on theirexplanatory power for evolutionary phenomena. If speciation were real, butsubject to finite limits of variation, then microevolution very well mightbe confirmed without the collateral concept of macroevolution beingestablished at all. A creationist view allows for some speciation because ofthe wide range of definitions, but does not support higher taxonation.

Essentialism
A variety of terms have been used in the past to describe species for thelimited view of variation: immutable, [3] constancy, [4] essences, [5] fixity, [6] types, [7] and kinds. [8] The underlying idea is that organisms are grouped bylimited expressions, such that gaps exist between fundamental groups.Today's young earth creationist is not a strict essentialist, in thatvariation is expected and thoroughly acknowledged. On the other hand, gapsbetween groups are said to be common, and seldom, if ever, bridged. Mayr [9]reviews the contrast of thoughts: "Essentialism with its emphasis ondiscontinuity, constancy, and typical values ("typology"), dominated thethinking of the western world to a degree that is still not yet fullyappreciated by the historians of ideas. Darwin, one of the first thinkers toreject essentialism (at least in part), was not at all understood by thecontemporary philosophers (all of whom were essentialists), and his conceptof evolution through natural selection was therefore found unacceptable.Genuine change, according to essentialism, is possible only through thesaltation of new essences."

Overview
Speciation, like its parent concept, evolution, is said to be a fact, eventhough few beginning-to-end examples can be given for it. Bush [10] states:"Furthermore, speciation is usually a rare event, seldom, if ever, observedfrom start to finish. Our current concepts of speciation are thereforeprimarily based on post hoc reconstructions of past events, or derived fromtheoretical population genetic models usually based on classical Mendelian genetics, with all the inherent weaknesses and speculative nature of theseapproaches. The post hoc approach is, at best, subjective, and it is thusnot surprising that recent advances in molecular biology call into questioncertain widely held conclusions of the naturalists and populationgeneticists (Crick, 1979)."

This is not to deny that speciation occurs. Much evidence implies thatisolating processes are establishing unique populations all the time.Indeed, in the case of ploidy, a new isolated species (depending on thedefinitions) can occur in one generation. However, if speciation (primarilyreproductive isolation) is the process of microevolution, and, in turnmacroevolution, as some proponents hold, then we are once again in theprecarious position of declaring that the fact of speciation leads directlyto the fact of macroevolution, without knowing very well how either takesplace, or the causative relation between the two.

Modes of Speciation
Mayr [11] lists twelve potential modes of speciation, not all of which havebeen observed (reworded below by author).

Potential Modes of Speciation

	Transformation of single species
		1.	Single species transformation by mutations, etc.
		2.	Single species transformation by genetic input from a second species
		3.	Fusion of two species by hybridization into a single species
	Multiplication of species by unique events
		1.	Asexual species mutating into a new species
		2.	Macrogenesis or hopeful-monster production
		3.	Chromosomal aberrations leading to new species
		4.	Chromosomal set multiplication within a species
		5.	Chromosomal set combining between species
	Multiplication of species by population events
		1.	New species formed within single populations—sympatry
		2.	New species formed at hybrid zones—semigeographic
		3.	New species formed by geographically isolated populations
		4.	New species formed by extinction within the range of the species

The first three modes only involve the change of starting species totallyinto following species without branching. The next five modes involvespeciation events that are peculiar in mechanics. The last four modesinvolve populations which are said to give rise gradually to more than onenew species through branching. Mayr gives no detailed examples of each ofthese modes at this citation, but does offer some general conclusions:First, speciation has come to mean principally the multiplication ofspecies; therefore, phyletic speciation (single species transformation) isnot of particular interest to evolutionists. Fusion of species is a retrograde process for evolution, and simply may be the breeding ofsubspecies that were incompletely identified.

Asexual species formation is complicated by the very definition of species,which is assigned, most generally, to reproductively isolated populations.Since vegetative processes are involved, every individual is reproductivelyisolated from all others at the outset. Commonly, such organisms are said tobelong to a collective species.

Macrogenesis is not known from real data, but is rather an hypotheticalconstruct. Many monsters have been born, but none are known to have givenrise to new species lines.

Chromosomal alterations, either in structure or number, are common. Indeed,the only direct evidence for speciation is found in the formation of polyploid organisms. Multiple sets of chromosomes make them unable to crosswith the parent species; hence they become new species, even though theymight look and behave very much like the parental lines.

Most speciation is said to be associated with gradual population changesunder the influence of geographical differences. The mechanisms for suchspeciation is hotly disputed, even though the population data seem toindicate definite levels of divergence or subspecies formation. Mayrconcludes, on page 513: "The widespread occurrence of geographic speciationis no longer seriously questioned by anyone."

Once again, we come to a dissettling conclusion regarding the process ofspeciation. Transformation within single species is not of highestimportance to evolution; unique speciation events are not a major source ofevolutionary change; and population events, like evolution as a whole, aresaid to be difficult to observe. Hard evidence (start to finish) forspeciation as a major process in evolution is obviously lacking.

Mayr, on page 48 comments: "Speciation is a slow historical process and,except in the case of polyploidy, it can never be observed directly by anindividual observer.... The method [of construction] most suitable forour purpose consists in the reconstruction of an essentially continuousseries by arranging fixed stages in the correct chronological sequence.... Stating our aim more specifically, it should be possible, speciation beinga slow process, to find natural populations in all stages of 'becomingspecies.'"

Summary
The wide variety of definitions for the term species today permits one toconclude that some new species are being formed from old species. Thus,speciation supporting microevolution (horizontal change), is an acknowledgedphenomenon. However, the critical category of speciation that wouldestablish macroevolution (vertical change) is said to be difficult todocument as a totally observed event. Although much literature has beenwritten to illustrate the concept, most of it is inferential. Even in thesewritings, a credible extrapolation of these transformations to establishhigher taxonation above the species level is very suspect.

Today's creationist interpretation of speciation would be given in anessentialist perspective claiming that even though the ancient "fixity of species" dogma is disproved by speciation events, there are also practicallimits to so-called "phyletic" change. These limits are seen in the historicand current documentation of discontinuities between types. This subjectwill be the theme of an upcoming article on "specialization."

[2] J. A. Endler, "Conceptual and Other Problems in Speciation," in D. Otle and J. A. Endler, Speciation and Its Consequences, (Sunderland, Massachusetts, Sinauer, 1989), pp. 625-648. Return to Text

[3] D. Kohn, "Theories to Work By: Rejected Theories, Reproduction, and Darwin's Path to Natural Selection" in W. Coleman and C. Limoges, Studies in History of Biology (Baltimore, Maryland, The Johns Hopkins University Press, 1980), p. 69. Return to Text

[4] J. Phillips, Life on the Earth (New York, Arno Press, 1980), pp. 191, 194 [Originally prepared in 1860]. Return to Text

[5] E. Mayr, "The Nature of the Darwinian Revolution," Science, 166 (1972): pp. 981-989. Return to Text

[6] M. Denton, Evolution: A Theory in Crisis (London, England, Burnett Books, 1985), pp. 17-367 [particularly p. 19].Return to Text

[7] C. Lyell, Principles of Geology (New York, D. Appleton and Co., 1853 Ninth Ed.), pp. 578-590 [particularly p. 579]. Return to Text

[8] H. Morris, Ed., Scientific Creationism (El Cajon, California, Master Books, 1984, Eleventh Ed.), pp. 51-54. Return to Text

[9] E. Mayr, The Growth of Biological Thought (Cambridge, Massachusetts, The Belknap Press, 1982), p. 38. Return to Text

[10] G. Bush, "What Do We Really Know About Speciation?" in R. Milkman, Perspectives on Evolution (Sunderland, Massachusetts, Sinauer, 1989), pp. 119-128 [particularly pp. 119, 120]. Return to Text

[11] E. Mayr, Animal Species and Evolution (Cambridge, Massachusetts, The Belknap Press, 1979), pp. 428, 488, 513. Return to Text