Chapter 23

Question 1

microevolution

Answer 1

change in the genetic makeup of a population from generation to generation

Question 2

natural selections happens on individuals or populations?

Answer 2

individuals

Question 3

can individuals evolve?

Answer 3

no, only populations

Question 4

population genetics

Answer 4

study of how a populations change over time

integrates Darwin and Mendel

Question 5

population

Answer 5

localized group of individuals

capable of interbreeding and producing offspring

Question 6

gene pool

Answer 6

total aggregate of genes in a population

Question 7

Hardy-Weinberg Theorem

Answer 7

frequencies of alleles and genotypes remain constant from generation to generation

preserved by Mendelian inhertiance

Question 8

conditions for H-W Theorem

Answer 8

extremely large population size

no gene flow

no mutations

random mating

no natural selection

Question 9

point mutation

Answer 9

change of one base in a gene that impacts the phenotype

usually harmless

Question 10

mutation rates

Answer 10

animals in plants: very low, 1 in 100,000

more rapid in microorganisms

Question 11

sexual recombination

Answer 11

combines new traits with those they were not with before

creates more genetic differences that make adaptation possible

Question 12

genetic drift

Answer 12

allele frequencies fluctuate unpredictably

tends to reduce genetic variation

Question 13

bottleneck effect

Answer 13

sudden change in the environment that reduces the size of the population

Question 14

founder effect

Answer 14

occurs when a few individuals become isolated from a large population

Question 15

gene flow

Answer 15

genetic additions or subtractions from a population

causes a population to gain or lose alleles

Question 16

discrete characteristics

Answer 16

classified on an either/or basis

ex: plant color

Question 17

quantitative characteristics

Answer 17

vary along a continuum

Question 18

phenotypic polymorphis

Answer 18

discrete characteristics

describes a population in which 2 or more forms are represented

Question 19

genetic polymorphisms

Answer 19

quantitative characteristics

heritable components that occur along a continuum

Question 20

geographic variation

Answer 20

difference between gene pools of separate populations

Question 21

cline

Answer 21

graded change in a trait along a geographic axis

Question 22

evolutionary fitness

Answer 22

contribution an individual makes to the gene pool

Question 23

relative fitness

Answer 23

contribution of a genotype to the next generation compared w/ alternative genotypes

Question 24

directional selection

Answer 24

favors individuals at one end of phenotypic range

Question 25

disruptive selection

Answer 25

favors individuals at both extremes of the phenotypic range

Question 26

stabilizing selection

Answer 26

favors intermediate variants and acts against extreme phenotypes

Question 27

diploidy

Answer 27

maintains genetic variation w/ hidden recessive alleles

Question 28

balancing selection

Answer 28

natural selection maintains stable frequencies of 2 or more phenotypic forms in a population

Question 29

heterozygous advantage

Answer 29

heterozygous individuals have greater fitness than homozygotes

Question 30

sexual dimorphism

Answer 30

differences between sexes in secondary sex characteristics

Question 31

intrasexual selection

Answer 31

competition among individuals of one sex for mating rights

Question 32

Why doesn’t natural selection create perfect organisms?

Answer 32

evolution is limited

adaptations are compromises

chance

selection can only edit existing variations