Several mass extinctions have occurred in Earth’s history

Are we currently living during another mass

extinction?

Biodiversity- refers to the number and variety of species on Earth Known species= 1.7 million Estimates = over 10 million

Species are considered known when they are collected and scientifically described

Species diversity- # of different species in an area (also called biodiversity)

Ecosystem diversity- variety of habitats and ecological processes w/in an ecosystem

Genetic diversity-different genes contained w/in all members of a population Gene- piece of DNA that codes for specific trait,

that could be inherited by offspring

Preserving ecosystem balance Keystone species- species that are critical

to the functioning of an ecosystem We depend on healthy ecosystem to ensure a

healthy biosphere

Genetic diversity within populations are critical to species survival

Diversity comes from large populations

Bottleneck effect- population shrinks due to sudden event

(natural disaster, human influence) leaving only a few

members thus reducing genetic diversity

Practical uses of species Clothing Shelter Medicine

¼ prescription drugs plants

Antibiotics fungi Food

Most new foods are hybrids- crops created by combining genetic information from various species

Aesthetic value or personal enjoyment Ecotourism- business that supports the

conservation and sustainable development of ecologically unique areas

Ethics Belief of some that species and ecosystems have

right to exist, regardless of their value

Species at risk• Species w/small populations• Migratory species• Those that need large tracts of land• Those exploited by humans

Endangered- likely to go extinct if protective measures are not taken immediately

Threatened- declining population and is likely to become endangered if it is not protected

Habitat Destruction & fragmentation Invasive exotic species

Exotic species- species not native to a particular area

Poaching- illegally hunting, fishing, harvesting, or trading wildlife

Pollution

Endemic species- species that are native to and found only within a limited area Tropical Rain Forest Coral Reefs & Coastal Ecosystems Islands

Most threatened areas of high species diversity on Earth