Biodiversity is life Biodiversity is our life

Biodiversity is life Biodiversity is our life

Chapter 10 Section 2 Biodiversity at Risk Objectives Define and give examples of endangered and threatened species. Describe several ways that species are being threatened with extinction globally. Explain which types of threats are having the largest impact on biodiversity. List areas of the world that have high levels of biodiversity and many threats to species. Compare the amount of biodiversity in the United States to that of the rest of the world.

Biodiversity at Risk Key Terms: Endangered species Threatened species Exotic species Poaching Endemic species

Major Extinction Events A sixth extinction?

Major Extinction Events Mass extinction extinction of many species in a relatively short period of time. The rate of extinction is estimated to have increased by a multiple of 50 since 1800. Between 1800 and 2100 up to 25% of all species on Earth may become extinct. Sixth extinction?

Endangered species are those likely to become extinct if protective measures are not taken immediately. Threatened species are declining in population and likely to become endangered if not protected.

Major human causes of extinction: Habitat destruction and fragmentation Introduction of non-native species Pollution Over-harvesting of species (Human population growth affects rate of extinctions.)

Habitat destruction and fragmentation It is estimated that habitat loss causes about 75% of current extinctions.

Habitat fragmentation - habitat broken up by roads, canals, fences, etc.

Habitat destruction and fragmentation Example: Florida Panther, which is the most endangered species in North America. Habitat loss is the major reason.

Introduction of non-native species Invasive exotic species are not native to a particular region. Can threaten native species that have no natural defenses. Example: invasive fire ants threaten livestock, people, and native species in southeastern United States.

Introduction of non-native species Kudzu Fire Ants

Pollution: Pesticides, cleaning agents, pharmaceuticals, other chemicals used by humans Example: Bald eagle and DDT

Over-harvesting of species Poaching harvesting wildlife illegally. Thousands of species are harvested and sold as pets, houseplants, wood, food, and herbal medicine. Many countries have laws to regulate hunting, fishing, harvesting, and trade of wildlife.

Poaching

Example: Bison numbers went from 60 million before North America was settled by Europeans to only 300 in 1906. Many killed for their tongues (considered a delicacy) and bodies were left to rot. Current population is 200,000 +.

Areas of Critical Biodiversity Endemic species species native to and found only within a limited area. Number of endemic species of plants are an indicator of overall biodiversity because plants form the basis of terrestrial ecosystems.

Areas of Critical Biodiversity Tropical Rain Forests Less than 7% of Earth s land surface; 50% or more of biodiversity Threats: clearing for farming, cattle grazing, logging

Areas of Critical Biodiversity Coral Reefs and Coastal Ecosystems Provide food, tourism revenue, coastal protection, sources of new chemicals Nearly 60% of coral reefs are threatened Threats: development along waterways, overfishing, pollution.

Example: Great Barrier Reef near Australia is the largest and maybe oldest reef (2000 km/1,250 miles long and 3,400 individual reefs).

Islands Areas of Critical Biodiversity Colonized by a limited number of species from mainland; Colonizing species evolve into several new species

Hawaiian Islands have 28 species of endemic birds (honeycreepers) endangered because of invasive exotic species. Threats: cattle and feral pigs that destroy habitat, rats that eat eggs and young birds, and introduced birds that have outcompeted the honeycreeper for habitat.

Biodiversity hotspots Biodiversity hotspots most threatened areas of high species diversity. High number of endemic species threatened by human activities. International conservationists have identified 25 biodiversity hotspots.

Biodiversity hotspots Most have lost at least 70% of their original vegetation. Most are tropical rain forests, coastal areas, or islands.

Biodiversity hotspots Example: Island of Madagascar Only 18% of original forests remain 80% of 10,000 flower plant species are endemic 91% of 300 reptile species are endemic All 33 species of lemur are found only in Madagascar

Examples of U.S. biodiversity hotspots: Florida Everglades California coastal region Hawaii Midwestern prairies Forests of the Pacific Northwest The U.S. has an unusually high number of species of freshwater fishes, mussels, snails, crayfish, pine trees, and sunflowers.