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bio ch 13 evolution Flashcards

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Biology 101 flashcards
1
Q

what is evolution

A

the idea that Earth’s many species are descendants of ancestral species that were different from those living today

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2
Q

what are fossils

A

the imprints or remains of organisms that lived in the past

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3
Q

what did the study of fossils reveal in the 1700s

A

a succession of fossil forms in layers of sedimentary rock that differed from current life-forms

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4
Q

what did lamark do/believe

A

suggested that organism’s evolve using fossil records
believed this happened by inheritance of acquired characteristics (i.e. giraffes got longer necks because their ancestor lengthened their necks and passed this on; didn’t happen/not true)

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5
Q

what happened to darwin that profoundly influenced his thinking

A

went on a round the world voyage on the HMS Beagle to chart poorly known stretches of the South American coast

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6
Q

what did Darwin notice while on his voyage

A

patterns of biodiversity; species vary globally, locally, and over time

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7
Q

who was darwin strongly influenced by

A

Charles Lyell and his book about geology that showed darwin that natural forces are gradually changing earth’s surface

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8
Q

what did darwin come to believe after the voyage and his readings

A

that the earth was actually very old and constantly changing and that it hadn’t been specially created only a few thousand years ago

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9
Q

what finally motivated Darwin to publish his ideas on his theory of evolution

A

in 1858, alfred wallace came up with a hypothesis almost identical to his and he didn’t want to lose credit/originality

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10
Q

what is darwin’s book called

A

“on the origin of species by means of natural selection”

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11
Q

what did dawson’s book do

A
  • presented the world with a logical and well-supported explanation for evolution
  • provided evidence that present day species arose from a succession of ancestors
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12
Q

what did darwin call his evolutionary history of life

A

descent with modification

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13
Q

what are adaptations

A

diverse modifications that fit a species to specific ways of life in their environment; any heritable characteristic that
increases an organism’s ability to survive and
reproduce in its environment

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14
Q

what did darwin propose was the mechanism of evolution

A

natural selection

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15
Q

what are the factors that shape a population

A

overproduction of offspring
limited natural resources
heritable variations

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16
Q

what is artificial selection

A

selective breeding of plants and animals to produce offspring with desirable traits; produces a great change in a short amount of time

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17
Q

what has artificial selection led to

A

greater yields of crops, meat, and milk

dogs like chihuahuas, dachshunds, and afghan hounds

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18
Q

what were darwin’s two concepts that led him to evolution

A

Diverse species have arisen by descent of
modification
The mechanism of modification is natural
selection working over long periods of time

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19
Q

what is fitness

A

how well an
organism can survive and reproduce in its
environment

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20
Q

what are the 2 observations that led darwin to make two inferences that led him to his idea of natural selection

A
  1. members of a population often vary in their observed traits
  2. all species are capable of producing more offspring than the environment can support
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21
Q

what are the 2 inferences darwin made from his two observations that led him to natural selection

A
  1. individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals
  2. this unequal production of offspring will lead to the accumulation of favorable traits in a population over generations
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22
Q

what is the essence of natural selection

A

unequal reproduction; individuals whose traits better enable them to obtain food, escape predators, or tolerate physical conditions will survive and reproduce more successfully, passing these adaptive traits to their offspring

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23
Q

is natural selection fast or slow

A

slow; it can modify species considerably over hundreds or thousands of generations

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24
Q

what are the 3 key points about evolution by natural selection

A
  1. individuals do not evolve; it is the population that evolves over time as adaptive traits become more common in the group and other traits change or disappear
  2. natural selection can amplify or diminish only heritable traits, not acquired traits
  3. evolution is not goal-directed and does not lead to perfectly adapted organisms; a trait favorable in one situation may be useless or detrimental in another
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25
Q

what is natural selection

A

favorable traits that allow an organism to
adapt to their environment result in successful
reproduction and survival of a species

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26
Q

what is a fossil record

A

Ordered array in which fossils appear within layers of sedimentary rock

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27
Q

what is an example of natural selection in action

A

ground finches in the galapagos and changes in beak size based on whether it was a dry year or wet year due to the type of seed that was in abundance for eating

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28
Q

what is another example of natural selection in action

A

the evolution of pesticide resistance in hundreds of insect species; the proportion of pesticide resistant ind

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29
Q

what are two important points about evolution

A
  1. natural selection is more an editing process than a creative mechanism
  2. natural selection is contingent on time and place
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30
Q

what are trace fossils

A

footprints, burrows, and other remnants of an ancient organism’s behavior

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31
Q

how can an entire organism be fossilized

A

when it is buried in a medium that prevents bacteria and fungi from decomposing the corpse

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32
Q

how can relative ages of fossils be determined

A

by the layer of strata in which they are found

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33
Q

why is our fossil record of history incomplete

A

not all organisms live in areas that favor fossilization
many rocks are distorted by geologic processes
not all fossils that have been preserved will be found

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34
Q

what does the fossil record reveal

A

the historical sequence in which organisms evolved; illustrate the transition of existing groups to new groups

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35
Q

what are the oldest known fossils

A

prokaryotes; there is evidence that prokaryotes are the ancestors of all life

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36
Q

what are the types of scientific evidence that support evolution

A

biogeography
comparative anatomy
comparative embryology
molecular biology

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37
Q

what is biogeography

A

the geographic distribution of species

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38
Q

what is an example of biogeography that supports evolution

A

the galapagos animals resembled species of the south american mainland more than they resembled animals on islands that were similar but much more distant. the logical explanation was that the galapagos species evolved from animals that migrated from south america.

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39
Q

what is homology

A

similarities in characteristics that results from common ancestry

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40
Q

what is an example of homology

A

the same skeletal elements make up the forelimbs of humans, cats, whales, and bats

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41
Q

what are homologous structures

A

features that often have different functions but are structurally similar because of common ancestry

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42
Q

what does comparative anatomy illustrate

A

that evolution is a remodeling process in which ancestral structures that originally functioned in one capacity become modified as they take on new functions

43
Q

what are vestigial structures

A

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

44
Q

what are some examples of vestigial structures

A

the small pelvis and hind-leg bones of ancient whales are vestiges of their walking ancestors
eye remnants that are buried under scales in blind fish species of cave fishes are vestiges of their sighted ancestors

45
Q

what has molecular biology enabled biologists to do

A

read a molecular history of evolution in the DNA sequences of organism

46
Q

what is the relationship between the number of differences in DNA sequences between species and how closely they are related

A

the more differences, the less related they are

47
Q

why does molecular biology provide strong evidence for the claim that all life forms are related

A

all forms of life use the same genetic language of DNA and RNA and the genetic code is essentially universal

48
Q

what is a population

A

a group of individuals of the same species that live in the same area and interbreed

49
Q

what is one example of evolution occurring within populations

A

the increasing proportion of resistant insects in areas sprayed with pesticide

50
Q

are members of one population more or less closely related to each other than to members of other populations

A

more bc they are most likely to choose mates locally

51
Q

what is a gene pool

A

the total collection of genes in a population at any one time

52
Q

what is a microevolution

A

when the relative frequencies of alleles in a population change over a number of generations

53
Q

where do new alleles originate from

A

mutations

54
Q

what is the ultimate source of genetic variation that serves as raw material for evolution

A

mutation

55
Q

what produces the genetic variation that makes evolution possible

A

mutation and sexual reproduction

56
Q

are mutation rates higher in prokaryotes or eukaryotes

A

prokaryotes

57
Q

what prevents most mutations in animals and plants from significantly affecting genetic variation from one generation to the next

A
  • low mutation rates
  • long time spans between generations
  • diploid genomes
58
Q

what are the 3 random components of sexual reproduction that contribute to genetic variation

A
  • crossing over
  • independent orientation of homologous chromosomes at metaphase 1 of meiosis
  • random fertilization
59
Q

what is the hardy-weinberg principle

A

Frequency of alleles in a gene pool are constant over time unless other factors are operating

60
Q

what 5 conditions must a population meet to satisfy the hardy-weinberg equation

A
  1. very large population
  2. no gene flow between populations
  3. no mutations
  4. random mating
  5. no natural selection
61
Q

what is the hardy weinberg equation used for

A

to test whether evolution is occurring in a population

62
Q

is the hardy-weinberg equilibrium common or rare

A

rare - does not exist in nature for long

63
Q

how is the hardy weinberg equation used by public health scientists

A

to estimate how many people carry alleles for certain inherited diseases

64
Q

what causes microevolution

A

natural selection, genetic drift, and gene flow

65
Q

what is genetic drift

A

a change in the gene pool due to chance

66
Q

the (smaller/bigger) the population, the more impact genetic drift is likely to have

A

smaller

67
Q

what is the bottleneck effect

A

a situation in which genetic drift can have a significant impact; drastic reduction in population usually due to a natural disaster

68
Q

what does the bottleneck effect do

A

reduces genetic variation because certain alleles will be present in a higher frequency than before, others will be present at lower frequencies, and others will not be present at all

69
Q

can human actions create severe bottleneck effects for other speicies

A

yes - florida panther, african cheetah

70
Q

what is the founder effect

A

a situation in which genetic drift can have a significant impact; when a few individuals colonize an island or other new habitat; the smaller the group, the less likely the genetic make up of the colonists will represent the gene pool of the larger population they left

71
Q

what is one thing that the founder effect explains

A

the relative high frequencies of certain inherited disorders among some human populations

72
Q

what is gene flow

A

Transfer of alleles between populations due to
members coming and going in and out of
populations

73
Q

does gene flow reduce or increase differences in population

A

reduce

74
Q

what is the only mechanism that consistently leads to adaptive evolution. why?

A

natural selection because some alleles are favored over others in a given environment

75
Q

why are endangered species endangered

A

Loss of genetic variation

Less able to adapt to new environments

76
Q

what three things cause gene variations

A

Mutations
Genetic recombination (meiosis)
Lateral gene transfer-organisms swap genes

77
Q

what are some examples of organisms where natural selection has led to adaptive evolution

A

blue footed boobies

cheetahs

78
Q

how does natural selection improve the match between organisms and their environment

A

by consistently favoring some alleles over others

79
Q

what is relative fitness

A

the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals

80
Q

who are the fittest individuals within the context of evolution

A

those that produce the largest number of viable fertile offspring and thus pass on the most genes to the next generation

81
Q

what is stabilizing selection

A

favors intermediate phenotypes

reduces variation and maintains the status quo

82
Q

what is directional selection

A

shifts the overall make up of the population by acting against individuals at one of the phenotypic extremes
most common during periods of environmental change/species migrating to a new environment

83
Q

what is disruptive selection

A

typically occurs when environmental conditions vary in a way that favors individuals at both ends of the phenotypic range over individuals with intermediate phenotypes

84
Q

what is sexual selection

A

a form of natural selection in which individuals with certain traits are more likely to obtain mates

85
Q

what is sexual dimorphism

A

the distinction in appearance between males and femailes

86
Q

what is intrasexual selection

A

individuals compete directly with members of the same sex for mates

87
Q

what is intersexual selection

A

individuals of one sex (usually females) are choosy in selecting their mates

88
Q

what is the advantage of females being choosy?

A

females prefer male traits that are correlated with “good genes”

89
Q

what helps prevent natural selection from making populations genetically uniform

A
  • having two sets of chromosomes; in a heterozygote, a recessive allele is protected from natural selection bc it wont exhibit that trait
  • natural selection -> balancing selection
90
Q

what is balancing selection

A

occurs when natural selection maintains stable frequencies of two or more phenotypic forms in a population

91
Q

what is heterozygote advantage

A

a type of balancing selection in which heterozygous individuals have greater reproductive success than either type of homozygote, with the result that two or more alleles are maintained in the population

92
Q

what is an example of heterozygote advantage

A

the protection from malaria conferred by the sickle cell allele

93
Q

what is frequency dependent selection

A

a type of balancing selection that maintains two different phenotypic forms in a population - selection acts agains either phenotypic form if it becomes too common in the population

94
Q

what is an example of frequency dependent selection

A

the scale eating fish in africa

95
Q

why cant natural selection fashion perfect organisms

A
  • selection can only act on existing variations
  • evolution is limited by historical constraints
  • adaptations are often compromises
  • chance, natural selection, and the environment interact
96
Q

what is a species

A

A species is a population that interbreeds and produces fertile offspring

97
Q

what is speciation

A

the formation of a new species; Caused by reproductive isolation

98
Q

what are the 3 types of reproductive isolation

A
  • behavioral
  • geographic
  • temporal
99
Q

what is behavioral isolation

A

behaviors of the organisms prevent them from mating

100
Q

what is geographic isolation

A

a population is separated by geographic barriers, but not

necessarily the whole population.

101
Q

what is temporal isolation

A

organisms reproduce at different times

102
Q

how do we measure speciation

A

molecular clocks

103
Q

what do molecular clocks do

A

measure mutation rates of DNA to estimate when the common ancestor became two separate species.

104
Q

what are HOX genes

A

During the embryo stage, hox genes control the development of the organism, decide when to turn genes on and off
mutations in the hox genes caused major evolutionary differences (like fins or legs)
Timing during development is critical

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