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General Ecology > Chapter 7 > Flashcards

Chapter 7 Flashcards

1
Q

What allows evolution by natural selection

A

genetic variation

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2
Q

Deoxyribonucleic acid (DNA):

A

a molecule composed of two strands of nucleotides that are wound together into a double helix

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3
Q

a molecule composed of two strands of nucleotides that are wound together into a double helix

A

Deoxyribonucleic acid (DNA)

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4
Q

what is each strand of DNA composed of?

A

nucleotides

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5
Q

Each nucleotide has

A

a sugar, a phosphate group, and one of four nitrogenous bases

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6
Q

nitrogenous bases

A

adenine (A), thymine (T), cytosine (C), and guanine (G)

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7
Q

what does the order of nitrogenous bases codes for

A

genetic information

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8
Q

chromosomes

A

compact structures consisting of long strands of DNA wound around proteins

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9
Q

compact structures consisting of long strands of DNA wound around proteins

A

chromosomes

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10
Q

what is a chromosome

A

a really long section of DNA, which is made of nucleotide unites

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11
Q

what are genes

A

different regions of DNA that code for particular proteins, which in
turn affect particular traits

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12
Q

alleles

A

different forms of a particular gene

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13
Q

different forms of a particular gene

A

alleles

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14
Q

what can changes in alleles create

A

differences in an organism’s phenotype

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15
Q

polygenic

A

when a single trait is affected by several genes; enables phenotypes to span a range of values in a population (e.g., human body height)

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16
Q

when a single trait is affected by several genes; enables phenotypes to span a range of values in a population (e.g., human body height)

A

polygenic

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17
Q

phenotype distributions are oftn

A

bell-shaped

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18
Q

pleiotropy

A

when a single gene affects multiple traits

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19
Q

when a single gene affects multiple traits

A

pleiotropy

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20
Q

epistasis

A

when the expression of one gene is controlled by another gene

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21
Q

when the expression of one gene is controlled by another gene

A

epistasis

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22
Q

every individual produced by sexual individuals has two copies of each gene,

A

one from its mother and one from its father

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23
Q

heterozygous

A

when an individual has two different alleles of a particular gene

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24
Q

homozygous

A

when an individual has two identical alleles of a particular gene

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25
Q

codominant

A

when two alleles both contribute to the phenotype

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26
Q

dominant

A

an allele that masks the expression of the other allele

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27
Q

recessive

A

an allele whose expression is masked by another allele; most harmful alleles are recessive

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28
Q

gene pool

A

collection of alleles from all individuals in a population

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29
Q

sexual reproduction combines haploid sex cells of two parents to from new combinations of alleles that

A

code for novel phenotypes

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30
Q

Random assortment

A

the process of making haploid gametes in which the combination of alleles that are placed into a given gamete could be any combination of those possessed by the diploid parent

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31
Q

the process of making haploid gametes in which the combination of alleles that are placed into a given gamete could be any combination of those possessed by the diploid parent

A

random assortment

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32
Q

mutation

A

a random change in the sequence of nucleotides (sugar, phosphate and nitrogen base) in regions of DNA that controls the expression of a gene

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33
Q

a random change in the sequence of nucleotides (sugar, phosphate and nitrogen base) in regions of DNA that controls the expression of a gene

A

mutation

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34
Q

mutations can be silent

A

no detectable effect

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35
Q

other mutations may

A

alter the physical appearance of an organism, or have lethal effects

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36
Q

setting the stage for meiosis: crossing over

A

during prophase 1, homologous pairs join together (synapsis) and exchange genetic information

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37
Q

what does exchange of DNA during prophase I do

A

increases genetic variability - chromatids are no longer exact duplicates

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38
Q

What happens during metaphase

A

chromosomes line up in pairs, but they line up randomly (random assortment)

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39
Q

Types of mutations

A
  1. point mutation
  2. chromosome inversion
  3. gene duplication
  4. polyploidy
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40
Q

point mutation description

A

base-pair substitutions in DNA sequences

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41
Q

point mutation cause

A

chance errors during DNA synthesis or during repair of damaged DNA

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42
Q

point mutation significance

A

creates new alleles

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43
Q

chromosome inversion description

A

flipping of a chromosome segment, so that the order of genes along the chromosome is altered

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44
Q

chromosome inversion cause

A

breaks in DNA caused by radiation

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45
Q

chromosome inversion significance

A

alleles inside the inversion are “locked together” into a unit

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46
Q

gene duplication description

A

duplication of a short stretch of DNA, creating an additional copy of a gene

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47
Q

gene duplication cause

A

unequal crossing over during meiosis

48
Q

gene duplication significance

A

the “extra” gene is free to mutate and perhaps gain new function

49
Q

polyploidy description

A

addition of a complete set of chromosomes

50
Q

polyploidy cause

A

errors in meiosis or (in plants) mitosis

51
Q

polyploidy significance

A

can create new species

52
Q

what can mutations cause in humans

A

fatal defects, diseases to become resistant to antibacterial drugs

53
Q

Recombination

A

the reshuffling of genes that can occur as DNA is copied during meiosis and chromosomes exchange genetic material

54
Q

the reshuffling of genes that can occur as DNA is copied during meiosis and chromosomes exchange genetic material

A

recombination

55
Q

during meiosis

A

pairs of homologous chromosomes (one from each parent) can exchange DNA in a process called crossing over

56
Q

crossing over can also occur between

A

nonhomologous chromosomes

57
Q

what does recombination do

A

helps the immune system rapidly evolve

58
Q

Driving forces of evolution

A
  1. mutations
  2. genetic drift (founder effect, bottlenecks)
  3. gene flow
  4. non-random mating
  5. natural selection (predation, parasitism, disease, competition, weather)
59
Q

mutations that negatively impact physiological functions are not favored by selection, but

A

a small fraction can be beneficial

60
Q

the more genes a species caries

A

the more likely at least one gene will mutate

61
Q

Genetic drift

A

a process that occurs when genetic variation is lost due to random variation in mating, mortality, fecundity, and inheritance

62
Q

a process that occurs when genetic variation is lost due to random variation in mating, mortality, fecundity, and inheritance

A

Genetic drift

63
Q

why is genetic drift more common in small populations

A

random events can have a disproportionately large effect on the frequencies of genes

64
Q

Bottleneck effect

A

a reduction of genetic diversity in a population due to a large reduction in population size (e.g., from loss of food).

65
Q

a reduction of genetic diversity in a population due to a large reduction in population size (e.g., from loss of food).

A

Bottleneck effect

66
Q

survivors of bottleneck effect

A

carry a fraction of the genetic diversity from the original population

67
Q

bottleneck effects can prevent a population from

A

adapting to future environmental changes, such as emergent disease

68
Q

Founder effect

A

when a small number of individuals leave a large population to colonize a new area and bring with them only a small amount of genetic variation

69
Q

when a small number of individuals leave a large population to colonize a new area and bring with them only a small amount of genetic variation

A

Founder effect

70
Q

Genetic drift can cause

A

additional reductions in genetic variation

71
Q

Genetic variation remains low until

A

enough time has passed to accumulate new mutations

72
Q

Selection

A

the process by which certain phenotypes are favored to survive and reproduce over other phenotypes

73
Q

the process by which certain phenotypes are favored to survive and reproduce over other phenotypes

A

Selection

74
Q

Stabilizing selection

A

when individuals with intermediate phenotypes have higher survival and reproductive success than those with extreme phenotypes

75
Q

when individuals with intermediate phenotypes have higher survival and reproductive success than those with extreme phenotypes

A

Stabilizing selection

76
Q

progeny

A

has a more narrow distribution of phenotypes

77
Q

stabilizing selection occurs when

A

the environment is relatively unchanging

78
Q

stabilizing selection generates

A

little evolutionary change

79
Q

directional selection

A

when individuals with extreme phenotypes experience higher fitness than the average population phenotype

80
Q

when individuals with extreme phenotypes experience higher fitness than the average population phenotype

A

directional selection

81
Q

Disruptive selection

A

when individuals with either extreme phenotype experience higher fitness than individuals with an intermediate phenotype

82
Q

when individuals with either extreme phenotype experience higher fitness than individuals with an intermediate phenotype

A

Disruptive selection

83
Q

by removing the intermediate phenotype

A

genetic and phenotypic variation increases

84
Q

at what level does microevolution operate on

A

population level

85
Q

at what levels can evolution be studied at

A

microevolutionary and macroevolutionary

86
Q

Microevolution

A

the evolution of populations; affected by random processes and selection

87
Q

the evolution of populations; affected by random processes and selection

A

Microevolution

88
Q

Artificial selection

A

Selection in which humans decide which individuals will breed; breeding is done with a preconceived goal for the traits in the population (e.g., dogs, wild mustard).

89
Q

Selection in which humans decide which individuals will breed; breeding is done with a preconceived goal for the traits in the population (e.g., dogs, wild mustard).

A

Artificial selection

90
Q

what does natural selection favor

A

trait combinations that provide higher fitness to an individual

91
Q

what kind of process is natural selection

A

ecological process

92
Q

ecological process

A

individuals interact with their environment, and traits that lead to greater fitness in an environment are passed on

93
Q

Industrial melanism

A

a phenomenon in which industrial activities cause habitats to become darker due to pollution; individuals possessing darker phenotypes
are favored by selection

94
Q

a phenomenon in which industrial activities cause habitats to become darker due to pollution; individuals possessing darker phenotypes
are favored by selection

A

Industrial melanism

95
Q

what level does macroevolution operate at

A

species level and higher levels of taxonomic organization

96
Q

Macroevolution

A

evolution at higher levels of organization including species, genera, families, orders, and phyla

97
Q

evolution at higher levels of organization including species, genera, families, orders, and phyla

A

Macroevolution

98
Q

speciation

A

the evolution of a new species

99
Q

the evolution of a new species

A

speciation

100
Q

Phylogenetic trees

A

hypothesized patterns of relatedness among different groups such as populations, species, or genera; depict which groups evolved from other groups

101
Q

hypothesized patterns of relatedness among different groups such as populations, species, or genera; depict which groups evolved from other groups

A

Phylogenetic trees

102
Q

Allopatric speciation

A

the evolution of new species through the process of geographic isolation

103
Q

the evolution of new species through the process of geographic isolation

A

Allopatric speciation

104
Q

Occurs when a single population is separated by a geographic event (e.g., formation of a river).

A

Allopatric speciation

105
Q

what do isolated populations experience

A

genetic drift, founder effects, and novel natural selection pressures; populations evolve separately

106
Q

Sympatric speciation

A

the evolution of new species without geographic isolation

107
Q

the evolution of new species without geographic isolation

A

Sympatric speciation

108
Q

sympatric speciation may occur as a result of:

A
  1. habitat isolation
  2. sexual preference
  3. polyploidy
109
Q

polyploid

A

a species that contains three or more sets of chromosomes; can also give rise to sympatric speciation.

110
Q

a species that contains three or more sets of chromosomes; can also give rise to sympatric speciation.

A

polyploid

111
Q

when do polyploids arise

A

when homologous chromosomes fail to separate during meiosis, producing diploid gametes. If a diploid egg is fertilized by a haploid sperm, a polyploid will develop

112
Q

a polyploid is unable to breed when

A

a diploid is genetically distinct from its parents

113
Q

homologous structures

A

skeletal elements of an animal/organism that, by virtue of similarity, suggest connection to a common ancestor

114
Q

analogous structures

A

similar structures that evolved independently in two living organisms to serve the same purpose

115
Q

convergent evolution

A

independent evolution of similar features in a species of different periods in time line

General Ecology (16 decks)

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