Continuing Evolution
Speciation: the formation of new species
The biological species concept
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Reproductive isolation
Prezygotic barriers (prevent formation of a zygote)
Postzygotic barriers (act after fertilization)
Modes of speciation
Allopatric speciation
Sympatric speciation
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Adaptive radiation
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Extinction
Background extinction vs. mass extinction
The Big Five mass extinctions
Ongoing evolution in the modern world
Antibiotic resistance
Pesticide resistance
Invasive species and rapid evolution
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The sixth extinction
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Coevolution
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