Innovation and Speciation:punctuated eqilibrium (Evolution)

by David Turell , Tuesday, June 20, 2017, 00:20 (2712 days ago) @ David Turell

This article supports the theory that the gaps in evolution are real:

https://cosmosmagazine.com/biology/new-modelling-backs-controversial-evolution-hypothesis

"Gould and Eldredge sought to explain so-called gaps in the palaeontological record – missing fossils assumed to represent transitional phases between ancient species and the modern ones into which they evolved – by suggesting they were an illusion.

"Evolution, they proposed, wasn’t a gradual process, marked by the slow accumulation of new characteristics. Rather, they said, “the history of evolution is not one of stately unfolding, but a story of homeostatic equilibria, disturbed only ‘rarely’ … by rapid and episodic events of speciation.”

"Two important principles underpinned their explanation, which they dubbed the theory of punctuated equilibria.

"The first was that once a species evolved, it tended to stay pretty much the same from thereon in until extinction ended its run. The second was that when part of a species became isolated from the rest and thus fell under new selection pressure, if it was going to evolve into something new it would do so very quickly (at least, on a geological scale).

***

"However, Landis and Schraiber, publishing on the preprint site bioRxiv, push the argument back in favour of speciation as a comparatively rapid, rather than gradual, process.
The title of their paper serves also as its bold conclusion: Punctuated evolution shaped modern vertebrate diversity.

"The pair constructed a mathematical model based on random probability distribution and fed in datasets derived from the morphological characteristics of about 50 clades (genetically-related groups of animals) covering mammals, birds, reptiles, fish and amphibians.

"The results fitted best within a framework of punctuated development, with long periods of stasis – averaging around 10 million years – between “jump processes” of “pulsed evolution” lasting as little as 100 generations.

"All of the data used concerned modern species. Landis and Schraiber suggest that future work integrating their work with the paleontological evolutionary research kick-started by Gould and Eldredge will throw up more detailed evidence about how rapid spurts of evolution and speciation are related."

Abstract of paper:

"The relative importance of different modes of evolution in shaping phenotypic diversity remains a hotly debated question. Fossil data suggest that stasis may be a common mode of evolution, while modern data suggest very fast rates of evolution. One way to reconcile these observations is to imagine that evolution is punctuated, rather than gradual, on geological time scales. To test this hypothesis, we developed a novel maximum likelihood framework for fitting L´evy processes to comparative morphological data. This class of stochastic processes includes both a gradual and punctuated component. We found that a plurality of modern vertebrate clades examined are best fit by punctuated processes over models of gradual change, gradual stasis, and adaptive radiation. When we compare our results to theoretical expectations of the rate and speed of regime shifts for models that detail fitness landscape dynamics, we find that our quantitative results are broadly compatible with both microevolutionary models and with observations from the fossil record."

http://biorxiv.org/content/biorxiv/early/2017/06/18/151175.full.pdf

Comment: The gaps are not entirely proven but supported. The gaps mean your fanciful cell communities must do advanced planning to coordinate all the anatomic and physiologic changes required. The whale series is the best example of the necessity for advanced anatomic planning to make the changes needed. Multiple exact mutations must occur all at once. They must all work with each other.