The good news is that it is in fact possible to not only slow down extinction, but to save some species from the danger of vanishing.
Northern elephant seals are nowadays numbered aroundalong the West Coast, although there were fewer than a hundred of them left alive just recently. National Library of Medicine, n.
For instance, low trees and shrubs, with or without a tall tree overstorey, are important as both food and cover in the habitats of some species of wild deer Odocoileus virginianus. George Church, the lead researcher An essay explaining the definition of extinction on the resurrection of a mammoth in Harvard University, believes these precursors of modern elephants would help turn the modern Arctic tundra back to grasslands: These include increasing deforestation and the heavy pressure of grazing by professional shepherds in its area.
Within a few years after the start of the project, the decline in tiger population was successfully arrested and now the population has started to rise. Apart from the widespread and extensive destructions of habitats, direct extermination of many species of wildlife has occurred through the actions of hunters and poachers.
Almost one in four mammal species, including four of the six remaining species of great apesand one in eight bird species were considered at significant risk of extinction at the start of the 21st century. Currently, there are 14, to 35, endangered species only in the United States; 16, species worldwide stand on the edge of dead-end human-caused extinction, and in order to save them, a significant amount of effort should be made.
The same is true for vegetation: The distributions of Cairnia scutulata, Ophrysia superciliosa, Choriotis nigriceps and several other birds have been greatly restricted during the past few decades.
In addition, the World Wildlife Fund noted in a report that vertebrate populations overall declined by 58 percent between and Mukherjee feels that the above faunal impoverishments have occurred not as a result of climatic or physiographic influences but as a result of human activities. Ordovician-Silurian extinction about million years agowhich included about 25 percent of marine families and 85 percent of marine specieswith brachiopods, conodontsbryozoansand trilobites suffering greatly.
Moreover, with the power of science, it is possible not only to reintroduce endangered animals to their natural environments, but to bring back those of them that are believed to have completely disappeared.
NASA; illustration by Don Davis Permian extinction about million to about million years agothe most dramatic die-off, eliminating about half of all families, some 95 percent of marine species nearly wiping out brachiopods and coralsand about 70 percent of land species including plantsinsectsand vertebrates.
There are ways, however, to slow down or even turn back the processes of extinction; one of them, the more traditional one, is the reintroduction of cage-bred species to their natural environments. A langur Presbytis johni which was widely distributed throughout South India a few decades ago is now confined to the southern part of Western Ghats only.
For instance, the pink headed duck Rhodonessa caryophyllacea which was commonly seen in Assam in the early s, can no longer be found now. Mammals, about 4, species exist today; the natural turnover rate is about 1 per years. Indeed, current rates of human-induced extinctions are estimated to be about 1, times greater than past natural background rates of extinction, leading some scientists to call modern times the sixth mass extinction.
Thus, there is still hope for planet Earth. Excessive increases in the populations of these and other large mammals are, therefore, harmful for preserving the other species of wild plants and animals.
This high extinction rate is largely due to the exponential growth in human numbers: Even in a relatively not-so-distant past, some animal species had gone extinct completely: Sadly, however, the large-scale commercial whaling operations in many countries are posing a serious threat to the survival of the whale species.
Even during the times of the Mughal rulers, India was very rich in virgin forests, climax vegetations, and clean natural habitats conducive to wildlife. In Eastern Africa, elephants and fire have been responsible for causing the rapid replacement of woodland and forest life by grasslands.
The size does not matter for nature: For example, gray wolves, who were almost completely killed during hunting across the whole North America by the end of s, are now a relatively prosperous species counting around 3, specimen. Roughly 86 percent of marine brachiopod species perished, along with many corals, conodonts, and trilobites.
Moreover, there are two kinds of extinction: Ranked in descending order of severity, they are: As against these fairly low natural rates, during the last three decades alone some 95 species of birds and 37 of mammals have become extinct.
Fire stimulates the production of more abundant, available, and nutritious fodder for the deer. Man has destroyed or greatly changed their habitats, occupying them himself.
For example, one study released in that examined extinction models from previous studies predicted that 5. The main threat faced by rhinoceros is the commercial value of its horns for which poachers kill rhinoceros.
Ecologists at the University of California, Santa Barbara, believe the two species that would be especially reasonable to resurrect are the woolly mammoth, the last of which died about years ago, and the passenger pigeon, a gray bird with a red breast, once common all over North America and, which had gone extinct in early s.
With increasing deforestation, urbanization, and population growth, many habitats of wild plants and animals have been changed or destroyed.Causes Of Animal Extinction Biology Essay.
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Published: 23rd March, Disclaimer: This essay has been submitted by a student. This is not an example of the work written by our professional essay writers. You can view samples of our professional work here. Armstrong says, "Extinction is a failure to adapt to change," and, "Extinction is a natural process." "Extinction comes from the failure to adapt to a changing environment." Word Count: /5(10).
- Definition & Explanation Extinction is the disappearance of a previously learned behavior when the behavior is not reinforced.
In this lesson, learn more about extinction in operant conditioning. In psychology, extinction refers to the gradual weakening of a conditioned response that results in the behavior decreasing or disappearing. In other words, the conditioned behavior eventually stops.
For example, imagine that you taught your dog to shake hands. Extinction definition is - the act of making extinct or causing to be extinguished. How to use extinction in a sentence.
the act of making extinct or causing to be extinguished. Humans could be causing the sixth mass extinction of the world through the effect the human species has on the planet earth. Human population density increases, climate change due to human activities and increased human exploration and interference of nature are some of the ways humans are on their way to causing the sixth mass extinction.Download