What Causes the Extinction of Plants & Animals?

Scientists theorize that the next mass extinction on earth could occur as soon as 2050, according to National Geographic News. Plant and animal species become extinct for different reasons, both natural and man-made. The loss of animal and plant life has negative implications for the survival of the human race. Because of this, it's important to understand what causes plant and animal extinction.

Foothill Yellow-Legged Frog
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The foothill yellow-legged frog faces extinction soon.

Habitat Loss

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Deforestation is causing habitat loss.

Deforestation and urbanization combine to create two reasons why plants and animals become extinct. Deforestation is leveling forests to harvest the wood or create space for building or agriculture, while urbanization is the turning of once-rural areas into cities. As the human population grows, more and more land has to be cleared and urbanized for living space. This shrinks habitat for animals and plants. Each year, 36 million acres of natural forest is leveled, according to the World Wildlife Fund. The forest provides habitat for 80 percent of the world's species, the group reports.

Global Warming

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Global warming is the ongoing increase in the Earth's atmospheric and ocean temperatures due to the greenhouse effect.

Global warming is the ongoing increase in the Earth's atmospheric and ocean temperatures created by the greenhouse effect; a temperature increase of even 1 degree can affect plant and animal life. The report cited by National Geographic News looked at 25 biodiverse areas around the world, such as the Caribbean Basin and the Cape Floristic Region in South Africa, and concluded that current carbon dioxide amounts eventually will double in the areas studied. This could lead to the extinction of 56,000 plant species and 3,700 animal species in those areas alone, the study found.

Exotic Species Introduction

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There is competition among native and exotic species for resources.

When animals and plants that are not native to a region are introduced to the ecosystem, they can cause serious damage to the local plants and animals, and potentially contribute to their extinction. Native species must compete with the exotic species for basic needs such as food and water. If the exotic species is more aggressive than the native species, the native species then runs the risk of extinction. The introduction of the Nile perch into the Lake Victoria ecosystem in Africa represents a prime example of this, according to "Causes and Consequences of Species Extinctions," a paper published by Princeton University Press. The Nile perch was introduced to the area in the 1950s and by the 1980s, a population boom of these fish contributed to the extinction of between 200 and 400 native fish species.

Overexploitation

Aquaculture
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Overexploitation makes it hard for a species to renew its numbers.

Overexploitation, also called overharvesting, is the excessive harvesting of an animal or plant species, making it harder for the species to renew its numbers. The Princeton University Press paper points to the Steller's sea cow, which was discovered in 1741, overexploited, and then became extinct in 1768. Save the Frogs, a frog conservation group, notes that several frog species feel the effects of overharvesting for food, pet and scientific purposes. Fish also fall prey to overexploitation. According to Greenpeace, more than 70 percent of fisheries worldwide are either "fully exploited, over exploited, or significantly depleted."