chapter twenty-two/twenty-three

Question 1

2 examples of evidence for natural selection

Answer 1

1. natural selection of soapberry bugs in response to introduced plant species
2. evolution of drug-resistant bacteria

Question 2

natural selection in response to introduced plant species

Answer 2

• soapberry bugs use beak to feed on seeds in fruit
• Southern Fl - longer beaks, balloon vine w/ larger fruit
• Central Fl - shorter beaks, golden rain tree w/ smaller fruit
• beak size has evolved in populations depending on size of fruit
• Fl - occurred in less than 35 years

Question 3

evolution of drug-resistant bacteria

Answer 3

• Staphylococcus aureus found on people
• became resistant to penicillin 1945
• became resistant to methicillin in 1961 - MRSA (dangerous pathogen)
• became resistant to vancomycin

Question 4

how does methicillin work

Answer 4

it inhibits protein used by bacteria in cell walls
- MRSA bacteria use dif protein in cell walls
- when exposed to methicillin, MRSA strains more likely to survive and reproduce

Question 5

what does natural selection edit or select?

Answer 5

traits already present in populations

Question 6

homology

Answer 6

similarity resulting from common ancestry

Question 7

homologous structures

Answer 7

anatomical resemblances that represent variations on a structural theme present in a common ancestor

Question 8

what does comparative embryology reveal?

Answer 8

anatomical homilies not visible in adult organisms

Question 9

vestigial structures

Answer 9

remnants of features that served important functions in the organism’s ancestors

Question 10

examples of homologies at molecular level

Answer 10

genes shared among organisms inherited from a common ancestor

Question 11

evolutionary trees

Answer 11

hypotheses about relationships among dif groups
- homologies form nested patterns
- branch points indicate common ancestors

Question 12

convergent evolution

Answer 12

evolution of similar or analogous features in distantly related groups

Question 13

how to analogous traits arise?

Answer 13

when groups independently adapt to similar environments in similar ways

Question 14

what does convergent evolution not provide information about?

Answer 14

ancestry

Question 15

what do fossil records provide evidence of?

Answer 15

extinction of species, origin of new group, changes within groups over time
- documented transition from land to sea in ancestors of cetaceans

Question 16

biogeography

Answer 16

geographic distribution of species, provides evidence of evolution

Question 17

endemic species

Answer 17

species that aren’t found anywhere else in the world

Question 18

implications of evolution

Answer 18

1. philosophy - no purpose/meaning to existence
2. religion - no goal, no morality, no ethics
3. politics - social darwinism, eugenics
4. psychology - human just another animal and is prisoner of animal urges
5. biology - links all living things to common ancestor

Question 19

do organisms evolve during their lifetime?

Answer 19

no

Question 20

natural selection of medium ground finches on Galapagos Islands

Answer 20

beak size varied on seeds available

Question 21

microevolution

Answer 21

change in allele frequencies in a population over generations

Question 22

3 mechanisms that cause allele frequency change

Answer 22

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

Question 23

what is the only thing that causes adaptive evolution?

Answer 23

natural selection

Question 24

what is a prerequisite for evolution?

Answer 24

variation in hereditable traits

Question 25

what provided evidence of discrete heritable units/genes?

Answer 25

Mendel's work on pea plants

Question 26

what is genetic variation caused by?

Answer 26

differences in genes or other DNA segments

Question 27

what is phenotype the product of

Answer 27

inherited genotype and environmental influences

Question 28

discrete characters

Answer 28

- classified on either/or basis - typically determined by single gene locus - white/purple flowers

Question 29

quantitative characters

Answer 29

- vary along continuum within pop - human heigh, intelligence

Question 30

what can genetic variability be measured as?

Answer 30

gene variability and nucleotide variability

Question 31

average heterozygosity

Answer 31

average percent of loci that are heterozygous in population

Question 32

how is nucleotide variability measured?

Answer 32

by comparing DNA sequences of pairs of individuals

Question 33

true or false: most species exhibit geographic variation, which includes differences between gene pools of separate populations

Answer 33

true

Question 34

genetic variation at the whole-gene level can be quantified as the average percentage of loci that are _______________

Answer 34

heterozygous

Question 35

new genes and alleles can arise by what?

Answer 35

mutation or gene duplication

Question 36

true or false: phenotypic variation is not always the result of genetic differences

Answer 36

true

Question 37

mutation

Answer 37

change in nucleotide sequence of DNA

Question 38

mutations in what type of cells can be passed to offspring?

Answer 38

gametes

Question 39

effects of point mutations

Answer 39

- in noncoding regions often harmless - can be neutral because of redundancy in genetic code - can result in change in protein production (harmful) - can result in change in protein production (beneficial)

Question 40

altering gene number/position

Answer 40

- chromosomal mutations that delete or disrupt or rearrange many loci are harmful - duplication of small pieces of DNA increases genome size and is usually less harmful - duplicated genes can take on new functions by further mutation

Question 41

mutation rates in animals/plants

Answer 41

low - repair systems fix many mutations - average: 1 mutation per 100,000 genes per generation

Question 42

comparison of mutation rates in prokaryotes and viruses

Answer 42

lower in prokaryotes, higher in viruses

Question 43

what can sexual reproduction do to existing alleles?

Answer 43

shuffle them into new combinations

Question 44

in organisms that reproduce sexually, what is more important that mutation to produce genetic differences?

Answer 44

recombination of alleles - crossing over

Question 45

population

Answer 45

localized group of individuals capable of interbreeding and producing fertile offspring

Question 46

gene pool

Answer 46

consists of all the alleles for all loci in a pop

Question 47

when is a locus fixed in a population?

Answer 47

if all ind. are homozygous for same allele

Question 48

total number of alleles at locus in diploid organisms

Answer 48

total number of individuals x 2

Question 49

p + q =

Answer 49

1

Question 50

what does the Hardy-Weinberg principle describe?

Answer 50

a population that isn't evolving - if pop doesn't meet criteria, it is evolving

Question 51

what does the Hardy-Weinberg principle state about the frequencies of alleles and genotypes in a pop?

Answer 51

they remain constant from generation to generation

Question 52

in a given population where gametes contribute to the next generation randomly, what won't change?

Answer 52

allele frequencies

Question 53

5 conditions for non evolving pops that are rarely met in nature

Answer 53

1. no mutations 2. random mating 3. no natural selection 4. extremely large population size 5. no gene flow

Question 54

natural selection

Answer 54

differential success in reproduction results in certain alleles being passed to the next generation in greater proportions

Question 55

genetic drift

Answer 55

allele frequencies fluctuate unpredictably from 1 gen to next - the smaller a sample, the greater the chance of deviation from a predicted result - tends to reduce genetic variation through loss of alleles

Question 56

founder effect

Answer 56

- when few individuals become isolate from larger population - allele frequencies in dif populations can be dif

Question 57

bottleneck effect

Answer 57

- severe drop in pop size due to change in environment - resulting gene pool may no longer reflect original pop's gene pool - if pop remains small, it may further be affected by genetic drift

Question 58

summary of genetic drift

Answer 58

- sig. in small populations - causes allele frequencies to change at random - can lead to loss of genetic variation within pop - can cause harmful alleles to become fixed

Question 59

gene flow

Answer 59

movement of alleles among populations - can be transferred through movement of fertile ind./gametes

Question 60

does gene flow increase or decrease variation over time?

Answer 60

decrease

Question 61

does gene flow increase or decrease fitness of pop?

Answer 61

decrease - lake erie water snake increase - insecticide resistance in mosquitos