This article has been cited by other articles in PMC.
Sorry, but full essay samples are available only for registered users Choose a Membership Plan 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 niches, etc.
Simpson saw interspecies competition as only rarely the cause of extinction of species or larger groups. He thought replacement of one group by another was generally passive. In the history of life it is a striking fact that major changes in the taxonomic groups occupying various ecological positions do not, as a rule, result from direct competition of the groups concerned in each case and the survival of the fittest, as most students would assume a priori.
On the contrary, the usual sequence is for one dominant group to die out, leaving the zone empty, before the other group becomes abundant. A classic example is the history of marine reefs.
Reef communities have been wiped out several times in the past million years, coinciding in four cases with Big Five events. For a species to survive for several million years, as many do, it must be well adapted to the physical and biological stresses normal in its environment.
Tree species, for example, that can withstand, or even benefit from, forest fires have presumably evolved this ability because forest fires are common in their environment. It may well be that most species have evolved ways of surviving anything that their environment can throw at them, as long as the stress occurs frequently enough for natural selection to operate.
This implies, in turn, that likely causes of extinction of successful species are to be found among stresses that are not experienced on time scales short enough for natural selection to act Extinction is evidently selective at certain times and places but the effects tend to be subtle and require careful analysis of large data bases.
Despite of many uncertainties, we can formulate a reasonable statement of the probable role of extinction, containing the following elements.
Survivors are most likely to be those organisms which fortunately pre-adapted to an unexpected stress.
Although the extinction does not make a creative contribution by itself, it may be decisive in sustaining or eliminating such structures. The major extinctions have a profound influence on the future: It is said to be an inevitable outcome.
But there are some who dictates that extinction plays no direct role in evolution, but generally, there is a role but the study carry out very weak.Jul 19, · The past decade has seen a resurgence of interest in extinction, yet research on the topic is still at a reconnaissance level, and our present understanding of its role in evolution is weak.
Despite uncertainties, extinction probably contains three important elements. endangered species, has the role of extinction been con-fronted in modernterms. GeorgeGaylord SimpsononExtinction In TempoandMode(5), Simpson detailed whatheconsid-ered to be the most important determinants of evolution.
Thesewere(chapterII) variability, mutationrate, character ofmutations,generationlength,populationsize, andnatural selection.
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 . The role of mass extinction in evolution At the most basic level, mass extinctions reduce diversity by killing off specific lineages, and with them, any descendent species they might have given rise to.
Extinction, from natural forces, is the role of natural selection. All things being otherwise equal, it's a strong indication that the species was not well adapted to surviving the environmental pressures.