Gene pool:The sum total of all alleles carried in all members ofapopulation.Agenepool represents all of thealleles present onthe chromosomes ofall members of a population and the relativeprominence or rarenessofeachallele.Agenepool canchangeovertime.New alleles arise by mutation or are introduced by immigration.Rare pre-existing alleles disappear when all individuals carrying themleavethepopulationordie.Microevolution: Alterations of a population's gene pool21-6
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 21-6 Gene pool Gene pool: The sum total of all alleles carried in all members of : The sum total of all alleles carried in all members of a population. a population. A gene pool represents all of th A gene pool represents all of the alleles present on the chromos e alleles present on the chromosomes of omes of all members of a population and the relative prominence or raren all members of a population and the relative prominence or rareness of each allele. of each allele. A gene pool can change over time. A gene pool can change over time. New alleles arise by mutation or are introduced by immigration. New alleles arise by mutation or are introduced by immigration. Rare pre Rare pre-existing alleles disappear when all individuals carrying them existing alleles disappear when all individuals carrying them leave the population or die. leave the population or die. Microevolution Microevolution: Alterations of a population : Alterations of a population’s gene pool. s gene pool
Apopulation is defined by its genotype frequencies and allelefrequencies, which together make up a gene pool.Phenotype frequency:The proportion of individuals in apopulation thatexpress aparticularphenotypeGenotype frequency:The proportion of total individuals in apopulation that carrya particular genotype.Allele frequency:The proportion of gene copies in a wholepopulation that are of a given allele type.21-7
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 21-7 Phenotype frequency Phenotype frequency: The proportion of individuals in a : The proportion of individuals in a population that express a particular phenotype. population that express a particular phenotype. Genotype frequency Genotype frequency: The proportion of total individuals in a : The proportion of total individuals in a population that carry a particular genotype. population that carry a particular genotype. Allele frequency Allele frequency: The proportion of gene copies in a whole : The proportion of gene copies in a whole population that are of a given allele type. population that are of a given allele type. A population is defined by its genotype frequencies and allele frequencies, which together make up a gene pool
Phenotype frequency: The proportion of individuals in apopulation that express a particular phenotype.Example:In apopulation of20humanindividuals,4peoplehaveblue-coloredeyes becausethey are homozygousfor the recessive Ballele at a particular "blue eyes" locus, where the alternative alleleis A.Molecular analyses showed that 12 individuals are of genotypeAA,4areofgenotypeAB.Phenotype frequency of blue eyes:4/20=0.2dark eyes: (20-4)/20=0.821-8
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 21-8 Phenotype frequency Phenotype frequency: The proportion of individuals in a : The proportion of individuals in a population that express a particular phenotype. population that express a particular phenotype. Example: In a population of 20 human individuals, 4 people have blue-colored eyes because they are homozygous for the recessive B allele at a particular “blue eyes” locus, where the alternative allele is A. Molecular analyses showed that 12 individuals are of genotype AA, 4 are of genotype AB. Phenotype frequency of blue eyes: 4/20 = 0.2 dark eyes: (20-4)/20 = 0.8
Genotype frequency:The proportion oftotalindividuals in apopulation that carry a particular genotype.Example:In a population of 20 human individuals,4people haveblue-colored eyes because they are homozygous for the recessive Ballele at a particular "blue eyes" locus,where the alternative alleleis A.Molecular analyses showed that 12 individuals are of genotypeAA, 4areofgenotypeAB.Genotype frequency of AA: 12/20=0.6AB:4/20=0.2BB:4/20=0.221-9
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 21-9 Genotype frequency Genotype frequency: The proportion of total individuals in a : The proportion of total individuals in a population that carry a particular genotype. population that carry a particular genotype. Example: In a population of 20 human individuals, 4 people have blue-colored eyes because they are homozygous for the recessive B allele at a particular “blue eyes” locus, where the alternative allele is A. Molecular analyses showed that 12 individuals are of genotype AA, 4 are of genotype AB. Genotype frequency of AA: 12/20 = 0.6 AB: 4/20 = 0.2 BB: 4/20 = 0.2
Allele frequency: The proportion of gene copies in a wholepopulation that are ofa given allele type.Example:In a population of 20 human individuals, 4 people haveblue-colored eyes because they are homozygous for the recessive Ballele at a particular "blue eyes" locus, where the alternative alleleis A.Molecular analyses showed that 12 individuals are of genotypeAA,4areofgenotypeAB.21-10
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 21-10 Allele frequency Allele frequency: The proportion of gene copies in a whole : The proportion of gene copies in a whole population that are of a given allele type. population that are of a given allele type. Example: In a population of 20 human individuals, 4 people have blue-colored eyes because they are homozygous for the recessive B allele at a particular “blue eyes” locus, where the alternative allele is A. Molecular analyses showed that 12 individuals are of genotype AA, 4 are of genotype AB