The Origin of Species

Species Biological Species

Ring Species

Barriers Prezygotic Habitat Isolation Behavior Isolation Temporal Isolation Mechanical Isolation Gametic Isolation Postzygotic Hybrid Sterility Hybrid Inviability Hybrid Breakdown

Habitat Isolation

Behavior Isolation

Temporal Isolation

Mechanical Isolation

Gametic Isolation

Hybrid Sterility

Hybrid Inviability

Hybrid Breakdown

Modes of Speciation

Allopatric Speciation

Adaptive Radiation

Sympatric Speciation Autopolyploidy

Sympatric Speciation Allopolyploidy

Macroevolution

Gradualism Also called “Neodarwinism” Small changes over time Supporter: Ernst Mayr

Punctuated Equilibrium Supporters: Niles Eldredge & Stephen J. Gould Speciation occurs in episodic events – large periods of time with little change and short periods of time with large changes

Evolutionary Trends Evolutionary trends are not goal oriented

Adaptive Radiation The emergence of numerous species from a common ancestor introduced into an environment, presenting a diversity of new opportunities and problems