The Persistence of Saltationism

Also, "punctuated equilibrium" isn't the same as "saltation". Optimisation is always non-linear - so when you get an environmental change, adaptation will be rapid at first (if extinction is avoided) and then asymptote to equilibrium. But no "saltation" is required. Saltation may nonetheless, occasionally happen. Elizabeth B Liddle

Who really discovered Punctuated equilibrium? Interesting article; "Scottish Horticulturalist Patrick Matthew Proposed More Accurate Theory of Gradual Evolution Before Charles Darwin Did, Geologist Argues" http://www.sciencedaily.com/releases/2010/11/101109133151.htm Even more interesting; Evolutionary biologist Soren Lovtrup in his paper Macroevolution and Punctuated Equilibria Systematic Zoology Vol. 30, No. 4 (Dec., 1981), pp. 498-500 wrote;

It might be anticipated that Darwin, the unbeatable master of ad hoc hypotheses, would be the first to attempt saving the micromutation theory from falsification by paleontological observations by means of "punctuated equilibria." He was indeed. In the fourth edition of On the Origin of Species (1866) we may read in the chapter on the imperfection of the geological record: "It is a more important consideration, clearly leading to the same result [viz., the unreliability of the fossil record], as lately insisted on by Dr. Falconer, namely, that the periods during which species have been undergoing modification, though very long as measured by years, have probably been short in comparison with the periods during which these same species remained with- out undergoing any change." This statement was preserved in a slightly modified form in the later editions (Peckham, 1959, p. 501). It thus appears that only ignorance can account for the fact that Eldredge and Gould are acknowledged as originators of the theory on punctuated equilibria.

The theory of punctuated equilibrium (PE) had been around for a long time before Gould and Eldredge and even Darwin had known about it. PE was a gradual theory of evolution, it had nothing to do with saltationism. As Soren Lovtrup wrote PE was an utter fraud theory, a completey ad hoc hypothesis set up to defend Darwinism from falsification by paleontological observations;

To the orthodox neo-Darwinian there is only one way out, to provide a plausible explanation of the fact that thepaleontological observations do not show what they ought to. Eldredge and Gould (1972) have tried to save the theory, that is, to ensure agreement between the Darwinian micromutation theory and the fossil record by means of their theory of punctuated equilibria. According to the latter it is suggested that the environment of living organisms does not change con- tinuously as usually envisaged by the Darwinians; rather, it may be constant for millions of years, during which time the living organisms remain as unchanged as the empirical evidence indicates.

This theory is nothing but a shrewd, perhaps, but not very well substantiated attempt to account for the discrepancy between the predictions of the neo-Darwinian theory and empirical reality, as demonstrated by the fossil record.

TheisticEvolutionist

Punctuated equilibrium has nothing to do with saltationism. Saltational evolution has been well documented, it was originally denied by the Neo-Darwinists but has since been accepted by the scientific community. Polyploidy, gene duplication, symbiogenesis and lateral gene transfer have the capacity to bring about relatively large changes that are saltational. Here's some useful references; Gregory, T. R. and Hebert, P. D. N. (1999). The modulation of DNA content: proximate causes and ultimate consequences. Genome Res. 9, 317–324. Serres MH, Kerr AR, McCormack TJ, Riley M. (2009). Evolution by leaps: gene duplication in bacteria. Biology Direct 4: 46. Richard M. Bateman, William A. DiMichele. (2002). Generating and filtering major phenotypic novelties: neoGoldschmidtian saltation revisited. In: Cronk QCB, Bateman RM, Hawkins JA, eds. Developmental genetics and plant evolution. London: Taylor & Francis. pp. 109–159. Guenter Theissen. (2009). Saltational evolution: hopeful monsters are here to stay. Theory in Bioscience. 128, 43-51. TheisticEvolutionist

"Imagine if evolution had included the caveat that saltations—rapid leaps—can occur by unknown mechanisms such that new fossil species can appear fully formed." Ah, it's statements like these that just keep me coming back, I gotta say. Imagine if relativity had included the caveat that accelerating objects can exceed the speed of light if they wish for it hard enough? Imagine if germ theory had included the caveat that sometimes microbes grow hundreds of feet tall and terrify cities with their radioactive breath? Look, the fossil record is not one of saltation merely by virtue of large gaps. That's insane. Continuing from that logic, each saltated organism must have lived for millions of years before reproducing another salatated organism. Otherwise, we have to make the assumption that other organisms existed between the two, and this is unwarranted because those organisms' fossils have not been found. Lenoxus

Collin @ 1

So what is the difference between saltation and punctuated equilibrium?

Saltation refers to major changes, possibly even the formation of a new species, in just one generation. Punctuated equilibria is Gould and Eldredge's theory that the rate of gradual evolutionary change, as revealed in the fossil record, has changed, sometimes quite drastically, from time to time. Seversky

Imagine if evolution had included the caveat that saltations—rapid leaps—can occur by unknown mechanisms such that new fossil species can appear fully formed. This would have destroyed Darwin's premise that species evolve by natural processes and we wouldn’t be talking about him today.

Nonsense, there is no reason why both gradual and saltational changes couldn't exist alongside each other, just like selection and genetic drift. And it's not as if saltation is thought to be commonplace. To quote from the summary of the article you cited:

In my view, gradual changes represent the usual mode of evolution, but are unlikely to be able to explain all key innovations and changes in body plans. Saltational changes involving hopeful monsters are probably very exceptional events, but since they have the potential to establish profound novelties sometimes facilitating adaptive radiations, they are of quite some importance, even if they would occur in any evolutionary lineage less than once in a million years.

Seversky

So what is the difference between saltation and punctuated equilibrium? My understanding is that saltation just means that new and complex forms just appear suddenly. Is there a proposed mechanism? Collin