Chapter 3.3 Biodiversity Kam Shan, Kazuka, Terry, Melody 8A

What is Biodiversity? Biodiversity: The number of different species in an area. Biodiversity has both economic and ecological value within an ecosystem. Economic Value Many species economically important to humans. Supplying people with food, raw materials for clothing, medicine, and others. Wildlife tours in rain forests, savannas, mountain ranges. Ecotourism is an important source of jobs and money. Ecological Value Keystone Species: Species that influences the survival of many other species in an ecosystem. Ex: Sea stars eat mussels. If sea stars disappear, mussels will outcompete in the ocean.

Factors Affecting Biodiversity Area More Area = More Species Ex: You will find more trees in a 100 square meter area than a 10 square meter area Climate Closer to equator = More species Ex: Forests in Latin America, Asia and Africa are the most diverse ecosystem. These rainforests cover 7 percent of the world but contain more than half of the world’s species Niche Diversity Coral reefs = More species Ex: There are many small places for organisms to live in and so more fish can be happy.

Gene Pool Diversity The organisms in a healthy population have a diversity of traits such as color, size and ability to fight disease. These traits are determined by genes. Genes: The structures in an organism’s cells that carry its hereditary information Species that lack a diverse gene pool are less able to adapt their ecosystem. Ex: A fungus once almost wiped out all the corn crops in United States. Fortunately, there were some genes that could fight off the fungus. Scientists used this variety to breed corn that could fight off the fungus.

Extinction of Species Extinction: Disappearance of all members in the species Once a population is dropped below a certain level, than the species cannot recover. Endangered: In danger or threatened of becoming extinct Example: Tigers, Giant pandas in China etc.

Causes of Extinction Habitat Destruction Habitat Fragmentation: To break large habitats to smaller isolated pieces. Poaching Poaching: Illegal killing or removal of wildlife from their habitats Pollution Polluted Water, Air and Soil Exotic Species Introducing new species into an ecosystem

Habitat Destruction and Poaching Habitat Destruction is the major cause of extinction of species Ex: Clearing forests to build towns. Some species cannot adapt the new surroundings. Habitat Fragmentation like cutting trees to build a road can harm the ecosystem. Trees are vulnerable to wind damage and plants are less likely to disperse their seeds. Animals also might get injured while crossing a road. Poaching: Many animals are hunted for their skin, fur, teeth, horns or claws. These parts are used for medicines, jewelry, clothing etc. Some endangered plants are removed from their habitats and sold as house plant or for medicine.

Pollution and Exotic Species Pollution: Substances that cause pollution are called pollutants. Animals may breathe in pollutants or drink polluted water. Plants can absorb pollutants and build up in other organisms through food chain. Pollutants can weaken organisms or cause birth defects. Exotic Species: Introducing exotic species can endanger biodiversity. Ex: European sailors began visiting Hawaii hundred of years ago and rats from the ship escaped onto Hawaii. There were no predators so the number of mice multiplied quickly. They ate the eggs of the nene goose. So the European sailors brought in the rat-eating mongoose. Unfortunately, the mongoose preferred eating the eggs more than the rats so the nene goose are now endangered.

Ways of Protecting Biodiversity Captive Breeding -Mating of animals in zoos or wildlife preserves Laws and Treaties -Convention on International Trade in Endangered Species is the most important treaty Habitat Preservation (Most Effective) -There are 7,000 nature parks, preserves and refuges

Captive Breeding & Laws and Treaties Captive Breeding: The scientists cares for the young ones and when they are old enough, they are released back into their natural habitat. Ex: California condor, the largest bird in North America increased their population through captive breeding. Due to habitat destruction, there were only 15 condors left in Today, there are more than 200 California condors. However the process was costly ($20 million) Laws and Treaties The Endangered Species Act prohibits trading products made out of endangered or threatened species. Some treaties are hard to enforce. But the treaties help a lot of endangered animals like the African elephants.

Habitat Preservation Habitat Preservation: The most effective way to protect biodiversity is by protecting the whole ecosystem. In 1872, Yellowstone National Park, the world’s first national park. It protects wildlife habitats as park and refuges. To be more effective, reserves contain characteristics of diverse ecosystem. Example: The reserves must be big enough for the whole population to live there. The reserve also must contain an variety of niches. Also, it is necessary to keep the air, water and land clean, control poaching and remove exotic species.

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