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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