Chapter 15

Question 1

evolution

Answer 1

change in genetic composition of populations over time

Question 2

evolutionary theory

Answer 2

understanding and applying the processes of evolutionary change to biological problems

Question 3

descent with modification

Answer 3

share a common ancestor and have diverged from one another gradually over time

Question 4

natural selection

Answer 4

increased survival and reproduction of some individuals compared with others based on more favourable traits

Question 5

population

Answer 5

group of individuals of a singe species that live and interbreed in a particular geographic area at the same time

Question 6

what is the origin of genetic variation?

Answer 6

mutation

Question 7

alleles

Answer 7

different forms of a gene

Question 8

adaptation

Answer 8

favoured trait that evolves through natural selection

Question 9

gene flow

Answer 9

migration of individuals and movements of gametes between populations can change allele frequencies

Question 10

population bottleneck

Answer 10

populations that are normally large but pass through environmental events that only a small number of individuals survive

Question 11

what happens if a population goes through a bottleneck?

Answer 11

it loses variation

Question 12

founder effect

Answer 12

change in genetic variation w hen a few pioneering individuals colonise a new region

Question 13

why do mating patterns alter genotype frequencies?

Answer 13

individuals in a population do not choose mates at random

Question 14

sexual selection

Answer 14

occurs when individuals of one sex mate preferentially with particular individuals of the opposite sex

Question 15

what is the opposite of sexual selection?

Answer 15

random mating

Question 16

what is the formula for allele frequency?

Answer 16

p = (number of copies of the allele in the population)/(total number of copies of all alleles in the population)

Question 17

what are the Hardy-Weinberg equations?

Answer 17

p + q = 1

p + 2pq + q = 1

Question 18

Hardy-Weinberg equilibrium

Answer 18

describes a model where allele frequencies do not change across generations and genotype frequencies can be predicted from allele frequencies

Question 19

what are the conditions of HW equilibrium?

Answer 19

no mutation, no selection among genotypes, no gene flow, infinite population size, random mating

Question 20

qualitative traits

Answer 20

discrete qualities

Question 21

quantitative traits

Answer 21

likely to show continuous quantitative variation

Question 22

stabilising selection

Answer 22

preserves the average characteristics of a population by favouring average individuals

Question 23

directional selection

Answer 23

changes the characteristics of a population by favouring individuals that vary in one direction from the mean of the population

Question 24

disruptive selection

Answer 24

changes the characteristics of a population by favouring individuals that vary in both directions from the mean of the population

Question 25

purifying selection

Answer 25

selection against any deleterious mutations to the usual gene sequence

Question 26

positive selection

Answer 26

favouring one phenotype over another

Question 27

synonymous substitution

Answer 27

substitution that does not change the encoded amino acid

Question 28

silent substitution

Answer 28

synonymous with synonymous substitution

Question 29

nonsynonymous substitution

Answer 29

does change the amino acid sequence encoded by a gene

Question 30

missense substitution

Answer 30

synonymous with nonsynonymous substitution

Question 31

pseudogenes

Answer 31

copies of genes that are no longer functional

Question 32

N

Answer 32

population size

Question 33

μ

Answer 33

neutral mutation rate

Question 34

average number of new mutations

Answer 34

μ * 2N

Question 35

m

Answer 35

rate of fixation of neutral mutations

Question 36

formula for rate of fixation of neutral mutations

Answer 36

m = 2Nμ(1/N)

Question 37

why can a heterozygous condition never become fixed in a population?

Answer 37

offspring of two heterozygotes will always include both classes of homozygotes

Question 38

disadvantages of sexual reproduction

Answer 38

recombination breaks up adaptive combinations of genes, reduces the rate of females passing genes on to offspring, dividing offspring into separate genders reduces the overall reproductive rate

Question 39

what is the effective reproductive rate of the asexual lineage?

Answer 39

twice that of the sexual lineage

Question 40

Muller's ratchet

Answer 40

accumulation of deleterious mutations in lineages that lack genetic recombination

Question 41

advantages of sexual reproduction

Answer 41

facilitates repair of damaged DNA, permits the elimination of deleterious mutations

Question 42

how does sexual reproduction eliminate deleterious mutations?

Answer 42

through recombination followed by selection

Question 43

lateral gene transfer

Answer 43

horizontal movement of individual genes, organelles, or fragments of genomes from one lineage to another

Question 44

gene duplication

Answer 44

allows genomes to acquire new functions

Question 45

gene family

Answer 45

group of homologous genes with related functions

Question 46

how does a gene family arise?

Answer 46

several successive rounds of duplication and sequence evolution

Question 47

in vitro evolution

Answer 47

new molecules are produced in the lab to perform new and useful functions