Moment of Extinction

In the early nineteenth century, Georges Cuvier 's observations of fossil bones convinced him that they did not originate in extant animals.

Moment of extinction

His work was able to convince many scientists on the reality of extinction. The rate at which extinctions occurred prior to humans, independent of mass extinctions, is called the "background" or "normal" rate of extinction. A rule of thumb is that one species in every million goes extinct per year Wilson A typical species becomes extinct within 10 million years of its first appearance, although some species survive virtually unchanged for hundreds of millions of years.

Just as extinctions reduce biodiversity by removing species form the earth, new species are created by the process of speciation, thus increasing biodiversity. Biodiversity refers to the diversity of species, as well as the variability of communities and ecosystems and the genetic variability within species CBC In the past, species diversity recovered from even mass extinction events, although it took millions of years.

It is estimated that ten million years or more have been required to attain prior levels of species diversity after a mass extinction event CBC Until recently, it had been universally accepted that the extinction of a species meant the end of its time on Earth. However, recent technological advances have encouraged the hypothesis that through the process of cloning, extinct species may be "brought back to life.

In order for such a program to succeed, a sufficient number of individuals would need to be cloned in the case of sexually reproducing organisms to create a viable population size. The cloning of an extinct species has not yet been attempted, due to technological limitations, as well as ethical and philosophical questions.

There are a variety of causes that can contribute directly or indirectly to the extinction of a species or group of species. In general, species become extinct when are no longer able to survive in changing conditions or against superior competition. Any species that is unable to survive or reproduce in its environment, and unable to move to a new environment where it can do so, dies out and becomes extinct.

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Extinction of a species may come suddenly when an otherwise healthy species is wiped out completely, as when toxic pollution renders its entire habitat unlivable; or may occur gradually over thousands or millions of years, such as when a species gradually loses out competition for food to newer, better adapted competitors. It has been estimated that around three species of birds die out every year due to competition.

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Genetic and demographic phenomena affect the extinction of species. Regarding the possibility of extinction, small populations that represent an entire species are much more vulnerable to these types of effects.

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Natural selection acts to propagate beneficial genetic traits and eliminate weaknesses. However, it is sometimes possible for a deleterious mutation to be spread throughout a population through the effect of genetic drift. A diverse or "deep" gene pool gives a population a higher chance of surviving an adverse change in conditions. Effects that cause or reward a loss in genetic diversity can increase the chances of extinction of a species.

Population bottlenecks can dramatically reduce genetic diversity by severely limiting the number of reproducing individuals and make inbreeding more frequent. The founder effect can cause rapid, individual-based speciation and is the most dramatic example of a population bottleneck. The degradation of a species' habitat may alter the fitness landscape to such an extent that the species is no longer able to survive and becomes extinct. This may occur by direct effects, such as the environment becoming toxic, or indirectly, by limiting a species' ability to compete effectively for diminished resources or against new competitor species.

Major climate changes, such as ice ages or asteroid impacts, and subsequent habitat degradation have been cited as major factors in many major extinctions in the past. Habitat degradation through toxicity can kill off a species very rapidly, by killing all living members through contamination or sterilizing them. It can also occur over longer periods at lower toxicity levels by affecting life span, reproductive capacity, or competitiveness. Habitat degradation can also take the form of a physical destruction of niche habitats.

The widespread destruction of tropical rainforests and replacement with open pastureland is widely cited as an example of this; elimination of the dense forest eliminated the infrastructure needed by many species to survive. For example, a fern that depends on dense shade to make a suitable environment can no longer survive with no forest to house it. Vital resources, including water and food, can also be limited during habitat degradation, causing some species to become extinct. William Eckman rated it it was ok Jan 14, Starks rated it liked it Jan 25, Evan rated it liked it Jan 17, Taa rated it it was ok Dec 04, Jorra added it Oct 12, Darren White marked it as to-read Oct 16, Matt marked it as to-read Dec 08, Sarah Bronte Connor marked it as to-read Sep 01, Degreef Kristof marked it as to-read Sep 06, James Kenyon marked it as to-read May 09, Alexis Mangandi marked it as to-read Mar 02, Nikky B marked it as to-read Apr 17, Aza Marael marked it as to-read Apr 25, Pattie marked it as to-read Feb 06, Erin M marked it as to-read Feb 07, Jolene marked it as to-read Apr 12, Marcella Monteiro marked it as to-read Jul 08, Chino marked it as to-read Sep 01, Evan marked it as to-read Jan 21, Anita Mcconnell marked it as to-read Jan 23, Douglas Sines is currently reading it Jan 24, Jo Williams marked it as to-read May 19, James marked it as to-read Sep 03, Ida marked it as to-read Sep 18, Serena added it Mar 04, There are no discussion topics on this book yet.

Paul Hardy makes corporate videos for a living, and relaxes by writing novels when no one's watching. Books by Paul R. Trivia About Moment of extinction. No trivia or quizzes yet. Like Lamarck, Lyell acknowledged that extinction could occur, noting the total extinction of the dodo and the extirpation of indigenous horses to the British Isles. Instead of the catastrophic floods inferred by Cuvier, Lyell demonstrated that patterns of saltwater and freshwater deposits , like those seen in the Paris basin , could be formed by a slow rise and fall of sea levels.

For Darwin, extinction was a constant side effect of competition. The current understanding of extinction is a synthesis of the cataclysmic extinction events proposed by Cuvier, and the background extinction events proposed by Lyell and Darwin. Extinction is an important research topic in the field of zoology , and biology in general, and has also become an area of concern outside the scientific community. A number of organizations, such as the Worldwide Fund for Nature , have been created with the goal of preserving species from extinction.

Governments have attempted, through enacting laws, to avoid habitat destruction, agricultural over-harvesting, and pollution. While many human-caused extinctions have been accidental, humans have also engaged in the deliberate destruction of some species, such as dangerous viruses , and the total destruction of other problematic species has been suggested. Other species were deliberately driven to extinction, or nearly so, due to poaching or because they were "undesirable", or to push for other human agendas. One example was the near extinction of the American bison , which was nearly wiped out by mass hunts sanctioned by the United States government, to force the removal of Native Americans , many of whom relied on the bison for food.

Biologist Bruce Walsh of the University of Arizona states three reasons for scientific interest in the preservation of species: In modern times, commercial and industrial interests often have to contend with the effects of production on plant and animal life. However, some technologies with minimal, or no, proven harmful effects on Homo sapiens can be devastating to wildlife for example, DDT. Governments sometimes see the loss of native species as a loss to ecotourism , [76] and can enact laws with severe punishment against the trade in native species in an effort to prevent extinction in the wild.

Nature preserves are created by governments as a means to provide continuing habitats to species crowded by human expansion. The Convention on Biological Diversity has resulted in international Biodiversity Action Plan programmes, which attempt to provide comprehensive guidelines for government biodiversity conservation.

Advocacy groups, such as The Wildlands Project [77] and the Alliance for Zero Extinctions, [78] work to educate the public and pressure governments into action.

People who live close to nature can be dependent on the survival of all the species in their environment, leaving them highly exposed to extinction risks. However, people prioritize day-to-day survival over species conservation; with human overpopulation in tropical developing countries , there has been enormous pressure on forests due to subsistence agriculture , including slash-and-burn agricultural techniques that can reduce endangered species's habitats.

Antinatalist philosopher David Benatar concludes that any popular concern about non-human species extinction usually arises out of concern about how the loss of a species will impact human wants and needs, that "we shall live in a world impoverished by the loss of one aspect of faunal diversity, that we shall no longer be able to behold or use that species of animal.

The poliovirus is now confined to small parts of the world due to extermination efforts. Dracunculus medinensis , a parasitic worm which causes the disease dracunculiasis , is now close to eradication thanks to efforts led by the Carter Center. Treponema pallidum pertenue , a bacterium which causes the disease yaws , is in the process of being eradicated. Biologist Olivia Judson has advocated the deliberate extinction of certain disease-carrying mosquito species. In a September 25, article in The New York Times , she advocated "specicide" of thirty mosquito species by introducing a genetic element which can insert itself into another crucial gene, to create recessive " knockout genes ".

She further argues that since species become extinct "all the time" the disappearance of a few more will not destroy the ecosystem: Removing one species sometimes causes shifts in the populations of other species—but different need not mean worse. Although trials are ongoing, she writes that if they fail: Wilson has advocated the eradication of several species of mosquito, including malaria vector Anopheles gambiae. Wilson stated, "I'm talking about a very small number of species that have co-evolved with us and are preying on humans, so it would certainly be acceptable to remove them.

I believe it's just common sense. Some, such as Harvard geneticist George M. Church , believe that ongoing technological advances will let us "bring back to life" an extinct species by cloning , using DNA from the remains of that species. Proposed targets for cloning include the mammoth , the thylacine , and the Pyrenean ibex. For this to succeed, enough individuals would have to be cloned, from the DNA of different individuals in the case of sexually reproducing organisms to create a viable population.

Though bioethical and philosophical objections have been raised, [87] the cloning of extinct creatures seems theoretically possible. In , scientists tried to clone the extinct Pyrenean ibex C. From Wikipedia, the free encyclopedia. For other uses, see Extinct disambiguation and Extinction disambiguation.

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Evolution as fact and theory Social effects Creation—evolution controversy Objections to evolution Level of support. Extinction vortex , Genetic erosion , and Mutational meltdown. Extinction risk from global warming. Effect of climate change on plant biodiversity , Effects of climate change on terrestrial animals , and Effects of climate change on marine mammals. Marine extinction intensity during the Phanerozoic.

Extinction

Millions of years ago. The blue graph shows the apparent percentage not the absolute number of marine animal genera becoming extinct during any given time interval. It does not represent all marine species, just those that are readily fossilized. The labels of the traditional "Big Five" extinction events and the more recently recognised End-Capitanian extinction event are clickable hyperlinks; see Extinction event for more details.

Eradication of infectious diseases. The Biology of Rarity: Causes and consequences of rare—common differences. Retrieved 26 May Watching, from the Edge of Extinction. Retrieved 30 May The New York Times. Journal of Theoretical Biology. Miller; Scott Spoolman Retrieved 6 May Retrieved July 26, Entering the sixth mass extinction".

Extinction - New World Encyclopedia

Moreover, we have unleashed a mass extinction event, the sixth in roughly million years, wherein many current life forms could be annihilated or at least committed to extinction by the end of this century. Leakey, Richard , The Sixth Extinction: Smithsonian Books, Washington D. Niles Eldredge, Time Frames: Guns, Germs, and Steel. URL accessed January 26 Archived February 16, , at the Wayback Machine. Archived from the original PDF on A Dictionary of Genetics 8th ed.

Transition from the Paleozoic to the Mesozoic Brachiopod Fauna". Conservation of Wildlife Populations: Demography, Genetics and Management. Archived from the original on January 13, Retrieved September 20, Annual Review of Ecology and Systematics. Introduced species, in turn, are seen as competing with or preying on native species or destroying their habitat.

In other words, greater genetic diversity can offer greater resilience. The End of the Line: How overfishing is changing the world and what we eat. Science , Vol , Issue , —, 10 September The sixth mass coextinction: Retrieved April 20, Whitfield; Scott, David E. Proceedings of the Royal Society B: When Life Nearly Died: