Origin of species
• What is a species?• Maintenance of
species.• Modes of speciation.• 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
Maintenance of species
• Reproductive isolating mechanisms
• Pre-zygotic• Post-zygotic
Pre-zygotic barriers
Post-zygotic barriers
Modes of speciation
Modes of speciation
• Allopatric speciation• Geographic isolation• Barriers:• Rivers, mountains,
Geographic isolation
Adaptive Radiation
Sympatric speciationAutopolyploid Allopolyploid
Rate of speciation