From The Scientist: Evidence for punctuated equilibrium lies in the genetic sequences of many organisms, according to a study in this week’s Science. Researchers report that about a third of reconstructed phylogenetic trees of animals, plants, and fungi reveal periods of rapid molecular evolution.
‘We’ve never really known to what extent punctuated equilibrium is a general phenomenon in speciation,’ said Douglas Erwin of the National Museum of Natural History in Washington, D.C., who was not involved in the study. Since its introduction by Stephen Jay Gould and Niles Eldredge in the 1970s, the theory of punctuated equilibrium – that evolution usually proceeds slowly but is punctuated by short bursts of rapid evolution associated with speciation – has been extremely contentious among paleontologists and evolutionary biologists.
While most studies of punctuated equilibrium have come from analyses of the fossil record, Mark Pagel and his colleagues at the University of Reading, UK, instead examined phylogenetic trees generated from genetic sequences of closely related organisms. [Paleontology, Evolution, Palaeontology, Biology, Tree, Phylogeny, Sequence]
Continued at “Genetic evidence for punctuated equilibrium”
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Based on the jounal Science paper “Large Punctuational Contribution of Speciation to Evolutionary Divergence at the Molecular Level” (Abstract)
John Latter / Jorolat
Evolution Research
http://evomech3.blogspot.com/
Punctuated equilibrium seems to be a part of Neo-Darwinism. It is a mixture of Natural selection and mutation(By Darwin and Hugo De Vries repectively).
In the full article, it is stated that speciation often occurs in isolation. i would like to question the fact. According to the Hardy-Weinberg’s equilibrium, speciation occurs in a area where migration, natural selection and genetic recombination are present. In isolation exept for natural selection, (that too at a later stage), none of the above processes are active, thus making speciation in such conditions rare. Anmyways, such a speciation will be more of adaptive radiation(Like Darwin’s finches) or the development of one species into another, like in the case of Porto-Santo rabbits.
Punctuated equilibrium seems to be a mix of Darwinism and mutation proposed by Hugo De Vries. The reason given for speciation was isolation(most of teh time).This is also called adaptive radiation(For eg: Darwin’s finches in the Galapagos islands). But I would like to mention a few points which question this statement. The Hardy-Weinberg equilibrium states that evolution does NOT occur when there is no migration, genetic drift or natural selection. In isolation, these would be present. Thus the previous species would just change into new ones, which happened in the case of Porto Santo rabbits.This sort of evolution is however rare. Major evolutionary changes have occured only when the environmental conditions change and there is scope for genetic recombination.
From,
Dr. Osophil Amalano Gastre