As per certain biology texts, extinction refers to the end of an organism or group of organisms viz. a particular species. The moment of extinction is considered to be the end of the last alive individual in the group. Although the capacity to recover might have been lost long before this point. Determining a moment is complex and usually done retrospectively because the potential range of a species might be too large. This complexity would lead to phenomena like Lazarus taxa where the species is assumed to be extinct and appears abruptly after a period of apparent absence.
Over 99% of all the species that once lived on the Earth amounting over five billion species are estimated to be extinct. As per the estimations on the number of current species, a range from 10 -14 million of which more than 1.2 million have been studied and more than 86% have not yet been discovered.
Since this could happen naturally due to a change in the climate or because of human activities like overhunting or due to destruction of habitat.
Causes of Extinction
Destruction of a habitat is the foremost reason of extinctions. As deforestation is carried out in tropical forests, it guarantees to be the prime cause of mass extinctions due to human activity.
Every species has their own specific habitat and food requirements. The more specific these localized habitat and requirements are, the higher the vulnerability of species to vanish off the habitat to livestock, agricultural land, cities and roads.The only species that would be alive in future would be the one which is highly protected.
Degradation and Fragmentation – Elements of habitat loss
Habitat is disturbed by various factors. Considering the prairie in the plow eradicated habitat of many prairie dogs and made its existence rare. Increasing inputs of sediments in rivers could destroy an habitat and degrade it completely. When large continuous habitats are transformed to isolated a little fragments they would go extinct.
Despite the uncertainties, extinction has three major elements.
- For species collectively, extinction is a probability if the killing stress is so rare beyond their experience and therefore outside the reach of natural selection.
- The mass extinctions would pave way for major restructuring of the biosphere where a few successful groups are eliminated allowing minor groups to expand.
- In few cases, there is evidence that extinction is selective argued by Darwin. It has been made impossible to predict which species are going to be the next victim of an extinction event.
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