Chapter 5

Vanishing species• Biodiversity = Variety of life in an area

– # of species

• Where is the greatest biodiversity?– Warm places more biodiversity than cold

• 163 mammal species in Canada• 367 mammal species in US• 439 mammal species in Mexico

• If two identical climates, then the larger area typically has more biodiversity.

• General rules:– 1) warmer areas have greater biodiversity

– 2) larger areas have greater biodiversity

• Why is biodiversity important?–Life needs life–biodiversity brings stability to an

ecosystem–Medicine–Genetic cross breeding can

increase productivity in food and animals.

• Threatened- Population of a species starts a rapid decline.

• Endangered- when a species # become so low that extinction is possible.

• Extinct- the disappearance of a species when the last of its members dies. – Can be local or world-wide

– Can occur naturally or due to unnatural disturbances

Threats to Biodiversity

• Habitat Loss- – The biggest threat to

biodiversity (natural and unnatural)

– when habitats are gone the essentials of life for some organisms are gone as well.

• Habitat Fragmentation-– The separation of wilderness areas

– Fragmentation can occur when roads, buildings, etc. are expanded into undisturbed wilderness.

– Fragmentation can occur naturally from flooding, mountain formation, etc.

• Biotic Issues of fragmentation- – Lack of range to feed and breed

– Lack of enough food

– Lack of migration routes

• Abiotic Issues of Fragmentation-– Climate change (edge effect = different

conditions at the edge of a biome then the middle)

– Lack of water and mineral resources

• Habitat degredation- damage to the habitat by pollution.– Water pollution- degrades aquatic

habitats

• Land Pollution- degrades land habitats. Can be….– Trash– Chemicals– Other items

• Introduction of Exotics (alien) species- The introduced species my out compete native species for resources.

Conservation Biology

• Conservation biology = a field of biology that studies methods and implements plans to protect biodiversity.

• Legal protection– Endangered Species Act (1973) – law

that made it illegal to harm any species on the endangered or threatened species list.

• Preserving Habitats- Protecting whole ecosystems– National wildlife refuges, parks, grasslands,

wilderness areas, forest, etc.

• Sustainable use- strives to let people use resources of a wilderness area in ways that will not damage the ecosystem.

• Habitat corridors- uses natural strips to connect small areas of habitat.– Allows for migration– Allows for a small area to “act” as a

larger area ecologically

• Reintroduction Programs- releasing an organism into an ecosystem where it once lived.

• Captivity- organism held by people. (I.e. Zoos)