Extinction, the Causes of Extinction and the Conservation of Biodiversity
Laboratory of Population Biology, Environmental Biology Division, National Institute for Environmental Studies, Onogawa, 16-2 Tsukuba 305-8506, Japan
Over 25% of species are currently categorized as threatened. Extinction is a natural process in organism evolution, and 99% of all organisms that have thus far existed are already extinct. Current extinction rates, however, is progressing at least 2,500 times faster than in the past. Ongoing extinction is so fast, in fact, that organisms may not be able to adapt environment and to evolve. Current biodiversity crisis is called “sixth extinction” because it is severer than five geological mass extinctions. Habitat destruction, overexploitation, and invasion of species through human activities are currently the major causes of species extinction. Global warming is also expected to pose a considerable threat to Earth’s organisms. I briefly review the nature of species extinction, its processes, causes, theoretical background, and ongoing threats.
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