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What is Biodiversity?The variety of life in an area that is determined by the number of different species in that area.
• There are 2 main types:
1) Genetic Diversity 2) Species Diversity
The variety of genes in a population
Number of different species in a community
Why is biodiversity important?
Teosinte: A distant relative of
corn w/ resistance to viral diseases
Domestic corn plant
Penicillin: Derived from bread mold
Madagascar Periwinkle: Used to treat childhood forms of leukemia
1)Direct economic value
2)Indirect value – ex. treatment of diseases
Extinction Rates
• The gradual process of becoming extinct is known as background extinction.
• Mass extinctions: When a large percentage of all living species become extinct in a relatively short period of time.
• 250 MYA: Over90% of species died
Estimated number of Extinctions since 1600
Group Main-land
Island Ocean Total Approximate Number of Species
Percent of Group Extinct
Mammals 30 51 4 85 4000 2.1
Birds 21 92 0 113 9000 1.3
Reptiles 1 20 0 21 6300 0.3
Amphibians 2 0 0 2 4200 0.05
Fish 22 1 0 23 19,100 0.1
Invertebrates 49 48 1 98 1,000,000+ 0.01
Flowering Plants
245 139 0 384 250,000 0.2
Five Most Recent Mass Extinctions
Ordovician Period (444 MYA)
Devonian Period (360 MYA)
Permian Period (250 MYA)
Triassic Period (200 MYA)
Cretaceous Period (65 MYA)