The Role Od Extinction in Evolution

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The Role of Extinction in Evolution

In contrast to the opposite phenomenon, speciation. This is surprising in view of the special importance Darwin attached to extinction, and because the number of species extinctions in the history of life is almost the same as the number of originations; present-day biodiversity is the result of a trivial surplus of originations, cumulated over millions of years. For an evolutionary biologist to ignore extinction is probably as foolhardy as for a demographer to ignore mortality.

According to Charles Darwin's view of extinction and its role;

-extinctions of species have occurred gradually and continuously throughout the history of life. - Sudden disappearances of many species (mass extinctions), did not actually occur. The sudden disappearances of the species from the fossil record were due only to unrecognized gaps in the temporal record. - species extinction is usually, sometimes, caused by the failure of competition between the species. - the extinction of species is closely tied to the process of natural selection and; a major component of progressive evolution. -an inevitable outcome.

Darwin listed the fundamental components of the evolutionary process: -reproduction
-inheritance
-variability
-struggle for life
-natural selection
…with its "consequences" divergence of character and the extinction of less improved forms.

As George Gaylord Simpson's perception, he stands contrary on Darwin's.

Simpson detailed what he considered to be the most important determinants of evolution. These were; variability, mutation rate, character of mutations, generation length, population size, and natural selection.

But missing from this chapter is any indication that extinction plays an important role in evolution. To be sure, chapter II includes occasional mention of specific extinctions, but not as significant drivers of evolution. Simpson noted that major extinctions provide opportunities (space, ecological...
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