I find it refreshing to find articles which disagree with the prevailing scientific dogma, such as Darwinism, which puts emphasis on selection as the main (or, apart from neutral evolution, only) driving force of evolution. Woodley’s article is such a case.

Woodley, M.A. [2007], On the possible operation of natural laws in ecosystems. Rivista di Biologia-Biology Forum 100: 475-486, suggests that natural Platonic laws may operate in ecosystems. He bases this claim on two kinds of law-like behaviour observed in nature: 1) adaptations towards specialization which can be looked at as typological lineage degeneration away from “ideal” archetypes, in which specialization makes species more sensitive to environmental perturbations; 2) occurrence of convergently evolved forms which suggest a limited number of niches or possible organismal body plans (Platonic moulds).

Ad 1) 19th century biologists like Haeckel (who was a Darwinist) and others after him have indeed distinguished successive phases of initial explosive diversification, specialization and degeneration leading to extinction in various fossil lineages (’Epacme’, ‘Acme’ and ‘Peracme’ of Ernst Haeckel [1866]. But extinction of animal groups is not a lawful phase of an evolutionary cycle, because the ancestors of extant forms have never passed through it (Rensch, B. [1954], Neuere Probleme der Abstammungslehre. Die Transspezifische Evolution. Ferdinand Enke Verlag, Stuttgart; Rensch, B. [1959], Evolution above the species level. Columbia University Press. N.Y.).

If Woodley were right, we would expect that species in high diversity regions, such as the tropics, where evolution is more advanced (Rohde, K. [1992], Latitudinal gradients in species diversity: the search for the primary cause. Oikos 65: 514-527) should have narrower niches (e.g., latitudinal ranges, habitats, etc.) than species in low diversity regions (at higher latitudes). However, a recent meta-analysis of the latitude niche breadth hypothesis and computer simulations failed to find support for it. Likewise, Rapoport’s rule, according to which latitudinal ranges are generally wider at high latitudes, does not generally apply to animals and plants.

Also, Kaufman’s work (Kaufman, S.A. [1993]. The origins of order. Self-organization and selection in evolution. Oxford University Press, New York Oxford) and some other recent studies suggest that evolution is not driven exclusively by natural selection, but that many characters evolve not because but in spite of selection: “spontaneous order is everywhere present’ and ‘many conceivable useful phenotypes do not exist’. He uses rugged fitness landscapes to illustrate the process of evolution. However, peaks in rugged fitness landscapes (which might at first glance be considered to be equivalent to archetypes) are not constant, and it is therefore doubtful that the peaks in such fitness landscapes correspond to Platonic archetypes.

Ad 2) In his discussion of the second point (limited number of available niches suggested by convergences), Woodley proceeds from Hutchinson’s niche definition as a species’ place in a multidimensional hyperspace and concludes that “in the absence of species distributions, the niche can have no substance, thus indicating that ‘vacant niche’ is simply a non-descriptive term at best”. But Hutchinson himself used the term “vacant niche”, and there is indeed no reason, even in the context of Hutchinson’s definition, why one shoud not refer to the possibility of the existence of more places in multidimensional hyperspace than are actually apparent (or “filled”) at at a particular point in time. One might prefer the term “potential” or “virtual” niches, but the term “vacant niche” has the advantage that it draws attention to the possibility that more species can be accommodated without the necessity of compressing already filled ones. As pointed out by Rohde, K. [2005], Nonequilibrium Ecology. Cambridge University Press, Cambridge: “A vacant or empty niche, thus, is simply a concise way of saying that more species could exist in a habitat, as suggested by comparative studies.” - On the other hand, Woodley admits the existence of vacant niches in the Platonian context: “The existence of a vacant niche when considered in the above light is also significant, as it indicates that abstract form, wholly separate from its biological realization, can exist within an ecological context. Species are attracted to and can evolve to fill niche vacancies, and in doing so can acquire a range of forms that would at least be in part predictable from a study of the vacancy.” Nevertheless, the number of niches must be limited, because onvergence and orthoselection occur in evolution and must be the result of the limited number of ‘Platonic moulds’. “However it is not the quality of the environment that is necessarily provoking the adaptation, it is indeed the degree of competition which forces a species to specialize.”

Generally, according to Woodley, whereas the prevailing Darwinian view assumes that evolution is primarily driven by contingencies, the typological view holds that evolution in ecosystems is essentially deterministic and orthogenetic. Importantly also, Woodley believes that convergent forms occur because they are useful for the ecosystem.

Empirical evidence does not support the view that evolution has filled all possible niches. There has been an accumulation of taxa in the course of evolution to the Recent, and there is no evidence that this accumulation was accompanied by a corresponding compression of niches. ” Examining species diversity of various groups in ecosystems as diverse as marine benthos, insects of fern, or parasites of marine and freshwater fishes, the conclusion must be that ” considering the vast differences in diversity of similar habitats or hosts ” only a small proportion of potential niches is occupied, which makes it unlikely that interspecific competition is of such overriding importance as often assumed (see the recent discussion in Rohde 2005).

I conclude that ‘natural laws’ are indeed likely to exist in nature which force evolution into certain ‘moulds’, although it is doubtful that these moulds are constant and correspond to Plato’s archetypes. There is no substantial evidence which supports the view that adaptive radiation generally is a lawful process of lineage degeneration, from less to more specialized forms. There is much evidence in support of the view that niche space is largely empty; the term ‘vacant niche’ is appropriate and useful for drawing attention to this. Interspecific competition is probably not as important as often assumed. - Woodley’s claim that “convergent forms occur because they are useful for the ecosystem” is not supported by any evidence and it seems indeed highly unlikely that this suggestion can even in principle be supported by empirical evidence.

See also

http://blog.une.edu.au/klausrohde/2007/01/31/vacant-niches/

and

http://blog.une.edu.au/klausrohde/2007/02/24/effective-evolutionary-time/

and

Food Web Theory Suggests Ecology May Be Governed By General Rules

http://www.sciencedaily.com/releases/2000/03/000309074625.htm

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