The Origin of Species

SpeciesBiological Species

Ring Species

BarriersPrezygotic

Habitat IsolationBehavior IsolationTemporal IsolationMechanical IsolationGametic Isolation

PostzygoticHybrid SterilityHybrid InviabilityHybrid Breakdown

Habitat Isolation

Behavior Isolation

Behavior Isolation

Temporal Isolation

Mechanical Isolation

Gametic Isolation

Hybrid Sterility

Hybrid Inviability

Hybrid Breakdown

Modes of Speciation

Allopatric Speciation

Adaptive Radiation

Sympatric SpeciationAutopolyploidy

Sympatric SpeciationAllopolyploidy

Macroevolution

Gradualism

Also called “Neodarwinism”Small changes over timeSupporter: Ernst Mayr

Punctuated Equilibrium

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

Origin of Evolutionary NoveltyMost novelties are modified versions of older structures

preadaptation

“Evo-devo”

Evolutionary Biology and Developmental Biology working together

Homeotic GenesHox Genes- position

information

Evolutionary TrendsEvolutionary trends are not goal oriented

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