Evolution

• SelectionNatural vs. artificialFitnessGalapagos FinchDirectional, Stabilizing, Disruptive SelectionPolymorphism = several forms of a species in same habitat

• Microevolution vs. MacroevolutionMicroevolution: change in allele frequencyMacroevolution: formation of new species

FieldAssistants

Chesapeake Bay Retrievers=

+

English Peppered MothExample

Before industrial revolution After industrial revolution

English Peppered Moth Example

Darwin’s 2 Major Ideas

• Variation within an species

(organisms of the same species do not look exactly alike)

• Not all the offspring produced survive(there is a struggle for existence)

Macroevolution: formation of new species

• Allopatric Speciation: formation of new species due to geographic (physical) barrier

• Sympatric Speciation: formation of new species due to genetic mutation or reproductive isolation (although they occur together)

• Adaptive Radiation: formation of new species due to new opportunities (niches)i.e. islands