Several key insights led to Several key insights led to Darwin’s idea for natural selection. Darwin’s idea for natural selection.

Darwin noticed a lot of variation in domesticated Darwin noticed a lot of variation in domesticated plants and animals.plants and animals.

Artificial selection is the process by which humans Artificial selection is the process by which humans select traits through breeding.select traits through breeding.

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– Darwin found convincing evidence for his Darwin found convincing evidence for his ideas in the results of artificial selectionideas in the results of artificial selection

The selective breeding of domesticated plants The selective breeding of domesticated plants and animalsand animals

Figure 13.2A

Hundreds to thousandsof years of breeding(artificial selection)

Ancestral dog (wolf)

Figure 13.2B

Natural selection is a mechanism by Natural selection is a mechanism by which individuals that have inherited which individuals that have inherited beneficial adaptations produce more beneficial adaptations produce more offspring on average than do other offspring on average than do other individuals.individuals.

• Heritability is the ability of a trait to be passed down.• There is a struggle for survival due to overpopulation

and limited resources.• Darwin proposed that adaptations arose over many

generations.

There are four main principles to the theory of natural There are four main principles to the theory of natural selection.selection.

– variationvariation

Natural selection explains how evolution Natural selection explains how evolution

can occur.can occur.

– overproduction

– adaptation– descent with modification

VARIATIONOVERPRODUCTIONADAPTATION

There are four main principles to the There are four main principles to the theory of natural selection.theory of natural selection.– VariationVariation– overproductionoverproduction– adaptationadaptation– descent with modificationdescent with modification

Fitness is the measure of survival ability Fitness is the measure of survival ability and ability to produce more offspring.and ability to produce more offspring.

Natural selection explains how evolution Natural selection explains how evolution

can occur.can occur.

Natural selection can act only on traits that Natural selection can act only on traits that already exist.already exist.

Structures take on new functions in addition to Structures take on new functions in addition to their original functiontheir original function..

Natural selection acts on existing variation.Natural selection acts on existing variation.

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Your Team MembersYour Team Members

Kennidra, Anna, Felicia, FaithKennidra, Anna, Felicia, Faith

Makay, Cole, Alex, FarrahMakay, Cole, Alex, Farrah

Haley, Marquasia, Caity, EricHaley, Marquasia, Caity, Eric

Tameshia, Whitney, Brittany C., DhanikaTameshia, Whitney, Brittany C., Dhanika

Brittany P., Crystal, Teresa, NicoleBrittany P., Crystal, Teresa, Nicole

Emily, Drennan, JuliaEmily, Drennan, Julia

Your Task Your Task

Find out all components on the bottom of Find out all components on the bottom of the cube. You can only view one side of the cube. You can only view one side of the cube and everyone can see the top. the cube and everyone can see the top. You can get information from other teams You can get information from other teams only if they want to share information with only if they want to share information with you.you.You have to write a short paragraph on You have to write a short paragraph on what your answer is and why you think it is what your answer is and why you think it is the correct answer. the correct answer.