chapter 17

Question 1

all the alleles of all the genes in a population; “genetic resources,” shared by all the members of the population (in theory)

Answer 1

the gene pool

Question 2

infrequent but inevitable changes in genes

Answer 2

mutations

Question 3

mutation is a source of…

Answer 3

new alleles/genetic variation

Question 4

crossing over at meiosis i introduces…

Answer 4

new combinations of alleles into chromosomes

Question 5

independent assortment at meiosis i mixes…

Answer 5

maternal and paternal chromosomes

Question 6

fertilization combines…

Answer 6

alleles from two parents

Question 7

changes in chromosome number or structure occur which are known as…

Answer 7

transposition, duplication, or loss of chromosomes

Question 8

individuals do not evolve, ______________ do

Answer 8

populations

Question 9

frequency of certain ________ is the result of evolution

Answer 9

traits

Question 10

a theoretical state in which an allele’s frequency never changes in a population’s gene pool

Answer 10

genetic equilibrium (population is not evolving)

Question 11

list the five conditions needed for genetic equilibrium

Answer 11

1. mutations never occur
2. mating is random
3. the allele does not affect survival or reproduction (i.e., there is no selection for or against that trait)
4. the population is infinitely large
5. no immigration or emigration

Question 12

when comparing a population’s gene pool to a control group, the “null hypothesis” is the population at…

Answer 12

genetic equilibrium

Question 13

at genetic equilibrium, proportions of genotypes at a locus with two alleles will remain the same

Answer 13

hardy-weinberg law

Question 14

what does the hardy-weinberg law/equation state?

Answer 14

p^2 + 2pq + q^2 = 1

Question 15

heterozygous genotypes for genetic diseases are known as “__________” for that disease, but remain unaffected themselves

Answer 15

carriers

Question 16

small scale changes (small group, short time) in allele frequencies that drive a population away from genetic equilibrium

Answer 16

microevolution

Question 17

the four main components of microevolution are…

Answer 17

1. mutation
2. natural selection
3. genetic drift
4. gene flow

Question 18

a difference in the survival and reproductive success of different phenotypes, not purposeful, it simply fills the nooks and crannies of opportunity

Answer 18

natural selection

Question 19

natural selection acts _________ on phenotypes and ___________ on genotypes

Answer 19

directly, indirectly

Question 20

a type of selection where one end of the spectrum of phenotypes is favored

Answer 20

directional selection

Question 21

a type of selection where the middle ground or “medium” phenotype is favored (extremes are NOT favored)

Answer 21

stabilizing selection

Question 22

a type of selection where the extreme phenotypes are favored and (the middle is NOT favored)

Answer 22

disruptive selection

Question 23

example of directional selection

Answer 23

peppered moths: coloration before, during, and after the industrial revolution

Question 24

example of stabilizing selection

Answer 24

birth weight and mortality rates

Question 25

example of disruptive selection

Answer 25

the beaks of birds with two types of seeds available (finches?)

Question 26

a type of selection that is due to nonrandom mating; leads to sexual dimorphism

Answer 26

sexual selection

Question 27

the term for different sexes having different traits

Answer 27

sexual dimorphism

Question 28

the term for the change in the frequency of an existing gene variant in a population due to random chance

Answer 28

genetic drift

Question 29

genetic drift is more prominent in __________ populations

Answer 29

small

Question 30

when alleles disappear and leave only one possible form of that gene left, it's known as

Answer 30

fixation

Question 31

an effect that is due to a reduction of population size that is so severe it reduces genetic diversity

Answer 31

the bottleneck effect

Question 32

an example of the bottleneck effect

Answer 32

elephant seal population was hunted down to 14-20 individuals, and is now at 130,000. electrophoresis revealed that there is now no allele variation at 24 genes

Question 33

an effect pronounced on isolated islands; when a small group of individuals start a new population and their gene pool overall differs a lot from the original

Answer 33

the founder effect

Question 34

island chains offshore that are prone to speciation

Answer 34

archipelagos

Question 35

colonization and genetic divergence lead to...

Answer 35

speciation

Question 36

examples of archipelagos

Answer 36

the galapagos, the hawaiian islands

Question 37

in absence of other bird species on the hawaiian islands, ____________ radiated to fill numerous niches

Answer 37

honeycreepers

Question 38

hawaii is home to ___% of fruit fly species

Answer 38

40

Question 39

an effect that tends to keep the gene pools of populations similar; counters the differences that result from mutation, natural selection, and genetic drift

Answer 39

gene flow