Evolution Chapter 5 - Origin and Maintenance of Genetic Variation

The Amount of Genetic Variation Affecting Fitness Limits the Response to Selection:

So Selection Won’t Lead to Evolutionary Change if There is No Variation

What is the Ultimate Origin of Genetic Variation?

Mutations

Mutations in Somatic Cells…

Affect Function of Organism

Mutations in Germ Cells…

Are More Important Because They are Passed on From Parent to Offspring

Too Many Mutations Can Lead to…

Prevention of Evolution; Frequent Loss of Beneficial Alleles Would Prevent Adaptation

Mutation Rate, to Some Extent, is…

Controlled by Genes, so it’s Technically a Trait Under Selection

Mutations With ___ ___ are More Common Than Those With ___ ___

Small Effects; Large Effects

Mutations are More Common in Males Because…

Males Have Higher Rates of Cell Division

How Random are Mutations?

They’re Random in the Effect They’ll Have, but Mutations are Not Random With Respect to Where They Occur in the Genome

What is Polyploidization?

The Doubling of a Complete Chromosome Set

What is Duplication?

The Copying of a DNA Sequence Without Loss of the Original

Neutral Genetic Variation is Maintained Through ___ and ____

Mutations, Which Increase it; Genetic Drift, Which Decreases it

How Does Mutations and Genetic Drift Maintain Neutral Genetic Variation?

Mutations Increase Variation, Drift Reduces it Within a Population

Adaptive Genetic Variation is Balanced Through ___ and ____

Mutations, Which Increases it; Natural Selection, Which Decreases it

How Does Mutations and Natural Selection Maintain Adaptive Genetic Variation?

Mutations Increase Variation, Natural Selection Reduces it

What are Genetic Polymorphisms?

Genetic Variation Among Individuals in a Population

How is Genetic Variation Maintained When Selection Acts Within a Population?

• Heterozygote Advantage

• Frequency Dependent Selection

• Equal Fitness Among Phenotypes

How is Genetic Variation Maintained When Selection Acts Across Populations?

• Local Adaptations

What is Heterozygote Advantage?

Aa Has a Higher Fitness Than AA or aa Because The Heterozygote Has More Variation

What is Frequency-Dependent Selection?

Fitness of a Phenotype Depends on How Common it is in the Population

What is Equal Fitness?

Sometimes Different Phenotypes Have Equal Reproductive Success; Hard to Measure in Nature

What are Local Adaptions?

A Traits Adaptability Depends on the Environment an Organisms is in; The Same Species May Vary Across Geographic Ranges