What Causes the Extinction of Plants & Animals?

The foothill yellow-legged frog faces extinction soon.
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What does it mean for a species to become extinct, and what causes extinction? ​Extinction​ means the permanent end of a species, and scientists theorize that the next mass extinction on earth could occur as soon as 2050. 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 and other life forms on the planet. Because of this, it's important to understand the causes of extinction and what you can do to help prevent it.

Destruction of Habitat

Deforestation and urbanization combine to create two causes of extinction. 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 are leveled, according to the World Wildlife Fund. The forest provides habitat for 80 percent of the world's species, who then lose their homes to human development.

Warming of the Planet

Global warming​ is the ongoing increase in the Earth's atmospheric and ocean temperatures created by the greenhouse effect - a temperature increase of even one degree can affect plant and animal life. Scientists 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.

Exotic Species Introduction

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. The Nile perch was introduced to the area in the 1950s; by the 1980s, a population boom of these fish contributed to the extinction of between 200 and 400 native fish species.

Overexploitation of Resources

Overexploitation​, also called ​overharvesting​, is the excessive harvesting of an animal or plant species, making it harder for the species to renew its numbers.

One tragic example of overexploitation is the Steller’s sea cow, which was discovered in 1741, overexploited, and then became extinct in 1768. The Stellar's sea cow was a relative of the manatee, although these slow-moving, herbivorous marine mammals could grow much larger - up to ten meters long! Sea cows were hunted to extinction by sailors only 27 years after they were first sighted.

Several frog species also feel the effects of overharvesting for food, pet and scientific purposes. Fish also fall prey to overexploitation. According to Greenpeace, many fisheries worldwide are overfished.

It's All Connected

Deforestation contributes to global climate change, which can lead to the overexploitation of resources and the introduction of invasive species. Many of the drivers of plant and animal extinction are connected to one another and have synergistic relationships, which makes preventing extinctions very complex.

However, the fact that may of these factors are related to human activities also means that we can make choices to influence them positively. Learning about the causes of extinction is the first step; taking actions to reduce our carbon footprint and purchasing goods that are produced sustainably are two things that we can do on a daily basis to slow the rate of plant and animal extinctions on the planet.

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