Ch. 23 Vocab

Question 1

the percent, on average, of a population’s loci that are heterozygous in members of the population

Answer 1

average heterozygosity

Question 2

a change in the nucleotide sequence of an organism’s DNA, ultimately creating genetic diversity

Answer 2

mutation

Question 3

differences between the gene pools of geographically separate populations or population subgroups

Answer 3

geographic variation

Question 4

a graded change in a character along a geographic axis

Answer 4

cline

Question 5

a localized group of individuals of the same species that can interbreed, producing fertile offspring

Answer 5

population

Question 6

the aggregate of all of the alleles for all of the loci in all individuals in a population

Answer 6

gene pool

Question 7

the condition describing a nonevolving population

Answer 7

Hardy-Weinburg equilibrium

Question 8

the principle that frequencies of alleles and genotypes in a population remain constant from generation to generation provided that only Mendelian segregation and recombination of alleles are at work

Answer 8

Hardy-Weinburg principle

Question 9

a process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next

Answer 9

genetic drift

Question 10

genetic drift that occurs when the size of a population is reduced, as by a natural disaster or human actions

Answer 10

bottleneck effect

Question 11

genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population

Answer 11

founder effect

Question 12

the transfer of alleles from one population to another, resulting from the movement of fertile individuals or their gametes

Answer 12

gene flow

Question 13

the contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals in the population

Answer 13

relative fitness

Question 14

natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals

Answer 14

directional selection

Question 15

natural selection in which individuals on both extremes of a phenotypic range survive or reproduce more successfully than do individuals with intermediate phenotypes

Answer 15

disruptive selection

Question 16

natural selection in which intermediate phenotypes survive or reproduce more successfully than do extreme phenotypes

Answer 16

stabilizing selection

Question 17

a form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates

Answer 17

sexual selection

Question 18

marked differences between the secondary sex characteristics of males and females

Answer 18

sexual dimorphism

Question 19

a direct competition among individuals of one sex for mates of the opposite sex

Answer 19

intrasexual selection

Question 20

selection whereby individuals of one sex are choosy in selecting their mates from individuals of the other sex

Answer 20

intersexual selection

Question 21

natural selection that maintains two or more phenotypic forms in a population

Answer 21

balancing selection

Question 22

greater reproductive success of heterozygous individuals compared with homozygotes; tends to preserve variation in gene pool

Answer 22

heterozygote advantage

Question 23

a decline in the reproductive success of individuals that have a phenotype that has become too common in a population

Answer 23

Frequency-dependent selection

Question 24

genetic variation that doesn’t appear to provide a selective advantage or disadvantage

Answer 24

neutral variation

Question 25

evolutionary change below the species level

Answer 25

microevolution