Saltation (biology)

In biology, saltation (from Latin, "saltus", "leap") is a sudden change from one generation to the next, that is large, or very large, in comparison with the usual variation of an organism. The term is used for occasionally hypothesized, nongradual changes (especially single-step speciation) that are atypical of, or violate, standard concepts involved in neo-Darwinian evolution. The unorthodox emphasis on saltation as a means of evolutionary change is called saltationism.

Saltation defies the orthodoxy of evolutionary theory, but there are some prominent proponents, including Carl Woese. Polyploidy (most common in plants but not unknown in animals) can be seen as a type of saltation. Polyploidy meets the basic criteria of saltation in that a significant change (in gene numbers) results in speciation in just one generation.

It is a popular misconception that punctuated equilibrium is a saltationist theory, often mistaken for Richard Goldschmidt's hypothesis of "Hopeful Monsters." [cite book|last=Gould|first=Stephen Jay|authorlink=Stephen Jay Gould|title=The Structure of Evolutionary Theory|publisher=Harvard University Press|pages=pp. 1006-1021|chapter=Punctuated Equilibrium's Threefold History|chapterurl=http://www.stephenjaygould.org/library/gould_structure.html|accessdate=2008-05-05 |quote= [T] he urban legend rests on the false belief that ... punctuated equilibrium became a saltational theory wedded to Goldschmidt's hopeful monsters as a mechanism. I have labored to refute this nonsensical charge from the day I first heard it.] However, punctuated equilibrium refers instead to a pattern of evolution where most speciation occurs relatively rapidly from a geological perspective (tens of thousands of years instead of millions of years), but through neo-Darwinian evolution, not by saltations.

In The Blind Watchmaker, Richard Dawkins equates Creationism to saltation.

In popular culture, a form of saltation appears to have emerged from misconceptions over currently accepted theories of evolution (the X-men and its various spin-offs being the most egregious examples).

ee also

* Catastrophism
* Phyletic gradualism
* Rapid modes of evolution

Notes and references