origin of species - wou homepagewou.edu/~guralnl/101origin of species.pdf · origin of species •...
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Origin of species
• What is a species?• Modes of speciation• Maintenance of
species• Rate of speciation
Species & Species concepts• Biological Species:• A population or group
of populations whose have the ability to interbreed with one another in nature, producing viable offspring
• Evolutionary species: fossil record, morphology
Modes of speciation
Modes of speciation
• Allopatric speciation• Geographic isolation• Barriers:• Rivers, mountains,
Geographic isolation
Sympatric speciation
• Polyploidy• Change in
chromosome number
Adaptive RadiationMany new species
Maintenance of species
• Reproductive isolating mechanisms
• Pre-zygotic• Post-zygotic
Pre-zygotic barriers
Temporal isolation
Post-zygotic barriers
Rate of speciation
Vertical slope slow Phenotypic change, Horizontal slope fast change
Speciation event
Existing species
Extinction
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