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Ecology > Ecology Exam 4 > Flashcards

Ecology Exam 4 Flashcards

1
Q

what are the steps of how a species originates from existing species

A

-populations are connected by gene flow
-a barrier to gene flow is established
-this population begins to diverge genetically
-this population is reproductively isolated, forming a new species

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2
Q

what is speciation

A

the process by which one species splits into two or more species, is at the focal point of evolutionary theory

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3
Q

what is microevolution

A

consists of changes in allele frequency in a population over time

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4
Q

what is macroevolution

A

refers to broad patterns of evolutionary change above the species level

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5
Q

____ form a bridge between microevolution and macroevolution

A

speciation

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6
Q

The biological species concept emphasizes ____ isolation

A

reproductive

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7
Q

what is a species

A

is a group of populations whose members can interbreed in nature and produce offspring; they do not breed successfully with members of other such groups

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8
Q

____ ____ between populations holds a species together genetically

A

gene flow

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9
Q

The biological species concept is based on the ____ to ____, not on physical similarity

A

potential to interbreed

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10
Q

what is reproductive isolation

A

is the existence of biological factors (barriers) that impede two species from producing viable, fertile offspring

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11
Q

what are hybrids

A

are the offspring that result from mating between different species

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12
Q

what are prezygotic barriers

A

-habitat isolation
-temporal isolation
-behavioral isolation
-mechanical isolation
-gametic isolation

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13
Q

how do prezygotic barriers block fertilization from occurring

A

-Impeding different species from attempting to mate
-Preventing the successful completion of mating
-Hindering fertilization if mating is successful

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14
Q

what is habitat isolation

A

Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers

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15
Q

what is temporal isolation

A

Species that breed at different times of the day, different seasons, or different years cannot mix their gametes

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16
Q

what is behavioral isolation

A

Courtship rituals and other behaviors unique to a species are effective barriers to mating

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17
Q

what is mechanical isolation

A

Morphological differences can prevent successful completion of mating

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18
Q

what is gametic isolation

A

Sperm of one species may not be able to fertilize eggs of another species

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19
Q

how do postzygotic barriers prevent hybrid zygote from developing into a viable, fertile adult

A

-Reduced hybrid viability
-Reduced hybrid fertility
-Hybrid breakdown

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20
Q

what is reduced hybrid viability

A

Genes of the different parent species may interact and impair the hybrid’s development or survival in its environment

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21
Q

can hybrids be sterile

A

yes, mules

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22
Q

what is hybrid breakdown

A

Some first-generation hybrids are fertile, but when they mate with each other or with either parent species, offspring of the next generation are feeble or sterile

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23
Q

The biological species concept cannot be applied to ____ or ____ organisms (including all prokaryotes)

A

fossils or asexual

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24
Q

The biological species concept emphasizes the ____ of gene flow

A

absence

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25
Q

can gene flow occur between morphologically and ecologically distinct species

A

yes, grizzly and polar bears

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26
Q

how does the morphological species concept define a species

A

-structural features
-body shape
-other structures

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27
Q

does the morphological species concept apply to sexual and asexual species

A

yes

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28
Q

what does the ecological species concept define a species in terms of what

A

its ecological niche

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29
Q

what role does the ecological species concept emphasize

A

disruptive selection

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30
Q

does the ecological species concept apply to both sexual and asexual species

A

yes

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31
Q

what are the two ways that speciation can occur

A

-allopatric
-sympatric

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32
Q

can speciation take place with or without geographic separation

A

yes

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33
Q

what happens in allopatric speciation

A

gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations

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34
Q

what does the definition of a barrier depend on

A

the ability of a population to disperse

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35
Q

Separated populations may evolve independently through ____, ____ ____, and ____ ____

A

mutation, natural selection, and genetic drift

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36
Q

Reproductive isolation may arise as a by-product of ____ divergence

A

genetic

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37
Q

what is a example of evidence of allopatric speciation

A

fruit flies taken from the same source population and allowed to adapt to different diets over several generations tend to choose mates adapted to the same diet

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38
Q

Regions with ____ geographic barriers typically have more species than do regions with _____ barriers

A

many, fewer

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39
Q

when reproductive isolation between populations increases what also increases

A

the distance between them increases

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40
Q

is physical separation alone a biological barrier

A

no

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41
Q

reproductive barriers are ____ to the organisms themselves

A

intrinsic

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42
Q

what occurs in sympatric speciation

A

speciation occurs in populations that live in the same geographic area

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43
Q

Sympatric speciation can occur if gene flow is reduced by factors including

A

-polyploidy
-sexual selection
-habitat differentitation

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44
Q

what is polyploidy

A

is the presence of extra sets of chromosomes due to accidents during cell division

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45
Q

is polyploidy more common in plants or animals

A

plants

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46
Q

how quickly can polyploidy produce new biological species in sympatry

A

within a single generation

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47
Q

what is a autopolyploid

A

is an individual with more than two chromosome sets derived from a single species

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48
Q

The offspring resulting from mating between polyploids and diploids have ____ fertility

A

reduced

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49
Q

what is allopolyploid

A

is a species with multiple sets of chromosomes derived from different species

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50
Q

Allopolyploids can successfully mate with each other, but cannot interbreed with either ____ species

A

parent

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51
Q

____ selection can drive sympatric speciation

A

sexual

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52
Q

what type of selection contributed to speciation in cichlid fish in Lake Victorie

A

sexual

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53
Q

____ speciation can also result from the appearance of new ecological niches

A

sympatric

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54
Q

what is a hybrid zone

A

a region in which members of different species mate and produce hybrids

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55
Q

____ are the result of mating between species with incomplete reproductive barriers

A

hybrids

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56
Q

A hybrid zone can occur in a ____ ____ where adjacent species meet

A

single band

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57
Q

Hybrids often have reduced ____ compared with parent species

A

fitness

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58
Q

The distribution of hybrid zones can be more complex if parent species are found in ____ within the same region

A

patches

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59
Q

what can result in the relocation of existing hybrid zones or the production of novel hybrid zones

A

change in environmental conditions

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60
Q

Breeding between hybrids and parent species can result in the transfer of ____ from one parent species to the other

A

alleles

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61
Q

In a changing environment: the transfer of novel alleles may help parent species do what with changing conditions

A

cope with changing conditions

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62
Q

If hybrids do not become reproductively isolated from their parent species, then three alternate outcomes are possible:

A

-reinforcement
-fusion
-stability

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63
Q

what does reinforcement do

A

strengthens reproductive barriers

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64
Q

when does reinforcement of reproductive barriers occur

A

when hybrids are less fit than parents

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65
Q

what does fusion do

A

weakens reproductive barriers

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66
Q

when does fusion occur

A

if hybrids are as fit as parents, there can be substantial gene flow between species

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67
Q

how does fusion occur

A

reproductive barriers weaken, fusion occurs and the two species become one. The hybrids are as fit or more fit than the parents, the two species may fuse back into one species

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68
Q

what does stability do

A

continued formation of hybrid individuals

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69
Q

what causes stability

A

Barriers remain the same if hybrids are fit and reproductive. Two species will remain separate but also continue to interact to produce some hybrid individuals

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70
Q

how can the rate of speciation be studied

A

using the fossil record, morphological data, or molecular data

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71
Q

what does punctuated equilibria describe

A

these periods of apparent stasis punctuated by sudden change

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72
Q

what are speciation rates

A

The punctuated pattern in the fossil record and evidence from lab studies suggest that speciation can be rapid

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73
Q

how many genes influence the formation of new species

A

Depending on the species in question, speciation might require change in a single gene or many genes

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74
Q

macroevolution is the cumulative effect of what

A

of many speciation and extinction events

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75
Q

The fossil record shows macroevolutionary changes over large time scales, for example:

A

-the emergence of terrestrial vertebrates
-the impact of mass extinctions
-the origin of key adaptations, such as flight

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76
Q

what is abiogenesis

A

the original evolution of life or living organisms from inorganic or inanimate substances

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77
Q

when did earth form

A

4.6 billion years ago

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78
Q

what did Oparin and Haldane hypothesize about the early atmosphere

A

is was a reducing environment

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79
Q

where did the first organic compounds may have formed in reducing conditions

A

near the openings of volcanoes

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80
Q

Some evidence suggests that the early atmosphere was neither ____ or ____

A

reducing, oxidizing

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81
Q

Organic compounds could have been produced in deep-sea ____ ____

A

hydrothermal vents

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82
Q

what was another source of organic molecules

A

meteorites

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83
Q

what is the abiotic synthesis of macromolecules

A

-RNA monomers have been produced spontaneously from simple molecules
-RNA polymers form spontaneously when a solution of monomers is dripped onto hot sand, clay, or rock
-Such abiotically synthesized polymers could have acted as weak catalysts on early Earth

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84
Q

how were vesicles formed

A

-Adding montmorillonite, a soft mineral clay common on early Earth, greatly increases the rate of vesicle formation, and some can self replicate.
-They can absorb organic molecules attached to montmorillonite particles through a selectively permeable bilayer

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85
Q

where did replication and metabolism first appear

A

protocells

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86
Q

where did protocells form from

A

from fluid-filled vesicles with a membrane-like structure

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87
Q

what was the first genetic material

A

RNA

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88
Q

what did RNA provide the template for

A

the formation of DNA

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89
Q

how does DNA differ from RNA

A

-more chemically stable
-replicated more accurately

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90
Q

what species is the fossil record biased towards

A

-existed for a long time
-were abundant and widespread
-had hard parts, such as shells or skeletons

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91
Q

how is the age of older fossils estimated

A

by using isotopes with long half-lives to date the rock layers above and below the fossil

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92
Q

can we find out the actual ages of fossils

A

no

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93
Q

how can the age of a fossil be determined

A

radiometric dating

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94
Q

can fossils contain isotopes

A

yes, they accumulated in the organisms when they were alive

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95
Q

how can the age of some fossils be estimated by measuring what

A

ratio of the radioactive isotope carbon-14 to the stable isotope carbon-12

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96
Q

how far can radiocarbon dating be used to date fossils

A

75,000 years old

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97
Q

do organisms take up isotopes with long half-lives

A

no

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98
Q

The evolution of unique mammalian features can be traced in the ____ ____

A

fossil record

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99
Q

Mammals belong to the group of animals called ____

A

tetrapods

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100
Q

what eons is the geologic record divided into

A

-hadean
-Archaean
-Proterozoic
-phanerozoic

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101
Q

what eon includes the last half billion years

A

Phanerozoic

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102
Q

what era did the Cambrian explosion occur

A

paleozoic

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103
Q

what periods are in the paleozoic era (oldest to youngest)

A

Cambrian, Permian

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104
Q

what periods are in the Mesozoic era (oldest to current)

A

Triassic, Jurassic, cretaceous

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105
Q

what period is in the Cenozoic era

A

-quaternary

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106
Q

what time frame is the holocene epoch

A

11.7 Ka to today

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107
Q

what epoch is in the quaternary period

A

holocene

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108
Q

what eras is the Phanerozoic divided into (oldest to youngest)

A

Paleozoic, Mesozoic, and Cenozoic

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109
Q

Major boundaries between eras correspond to major ____ events in the fossil record

A

extinction

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110
Q

when were dinosaurs abundant

A

Triassic, Jurassic, Cretaceous

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111
Q

what are the oldest known fossils

A

stromatolites (rocks formed by the accumulation fo sedimentary layers on bacterial mats)

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112
Q

what time do stromatolites date back to

A

3.5 billion years ago

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113
Q

when were prokaryotes Earth’s sole inhabitants

A

for more than 1.5 billion years

114
Q

is most atmospheric oxygen of biological origin

A

yes

115
Q

when did oxygen accumulate gradually in the atmosphere

A

2.7-2.4 billion years ago

116
Q

what did the oxygen revolution cause

A

the extinction of many prokaryotic groups

117
Q

the oldest fossils of eukaryotic cells date back to when

A

1.8 billion years

118
Q

what did eukaryotes originate from

A

endosymbiosis

119
Q

what is endosymbiosis

A

when a prokaryotic cell engulfed a small cell that would evolve into a mitochondrion

120
Q

what is an endosymbiont

A

is a cell that lives within a host cell

121
Q

All eukaryotes have mitochondria or remnants of mitochondria, but not all have ____ (chloroplasts and related organelles)

A

plastids

122
Q

Mitochondria and plastids likely descended from ____ cells

A

bacterial

123
Q

A hypothesis for the origin of mitochondria and plastids through serial ____

A

endosymbiosis

124
Q

what is the evidence supporting an endosymbiotic origin of mitochondria and plastids

A

-Inner membranes of both organelles are similar to plasma membranes of living bacteria
-DNA structure and cell division are similar to bacteria
-Both organelles transcribe and translate their own DNA
-Ribosomes are more similar to bacterial than to eukaryotic ribosomes

125
Q

what period did dinosaurs evolve and radiate

A

triassic

126
Q

what period did dinosaurs go extinct

A

end of the cretaceous period

127
Q

what did the evolution of eukaryotic cells allow for

A

a greater range of unicellular forms

128
Q

A second wave of diversification occurred when ____ evolved and gave rise to algae, plants, fungi, and animals

A

multicellularity

129
Q

what are the oldest fossils of multicellular eukaryotes

A

red algae

130
Q

when did the mesozoic era end

A

66 Ma

131
Q

when did the creataceous period end

A

66 Ma

132
Q

when did the permian period end

A

252 Ma

133
Q

when did the paleozoic era end

A

252 Ma

134
Q

when did the mesozoic era begin

A

252 Ma

135
Q

when did the triassic period begin

A

252 Ma

136
Q

when did the cambrian period begin

A

541 Ma

137
Q

when did the paleozoic era begin

A

541 Ma

138
Q

when did the phanerozoic eon begin

A

541 Ma

139
Q

what are the eras in order from oldest to youngest

A

paleozoic, mesozoic, cenozoic

140
Q

what are the periods of the paleozoic from oldest to youngest

A

cambrain, permian

141
Q

what are the periods of the mesozoic era from oldest to youngest

A

triassic, jurassic, cretaceous

142
Q

what are the eons from oldest to youngest

A

-hadean, archean, proterozoic, phanerozoic

143
Q

when did the hadean eon begin and end

A

4.56 Ga to 4.0 Ga

144
Q

when did the archean eon begin and end

A

4.0 Ga to 2.5 Ga

145
Q

when did the proterozoic eon being and end

A

2.5 Ga to 541 Ma

146
Q

what are the ediacaran biota

A

an assemblage of larger and more diverse soft-bodied organisms that lived 635 to 541 mya

147
Q

what was the Cambrian explosion

A

refers to the sudden appearance of fossils resembling modern animal phyla in the Cambrian period

148
Q

when did the trilobtes appear

A

during the cambrian explosion

149
Q

what animals appear before the Cambrian explosion

A

sponges, cnidarians, and mollusks

150
Q

what event provides evidence of predator-prey interactions

A

Cambrian explosion

151
Q

Molecular and fossil data suggest that the Cambrian explosion had a ____ ____

A

long fuse

152
Q

Fungi, plants, and animals began to colonize land about ____ million years ago

A

500

153
Q

what adaptations did plants evolve to survive on land

A

reproduction and avoiding dehydration

154
Q

____ and ____ are the most widespread and diverse land animals

A

arthropods, tetrapods

155
Q

what did tetrapods evolve from

A

lobe-finned fishes

156
Q

when did tetrapods evolve from lobe-finned fishes

A

365 mya

157
Q

what did the human linage evolve from

A

tetrapods

158
Q

when did the human lineage evolve from tetrapods

A

6-7 mya

159
Q

when did the modern human originate

A

195,000

160
Q

The rise and fall of groups depend on ____ and ____ rates within the group

A

speciation, extinction

161
Q

how many times have the landmasses of Earth formed a supercontinent

A

three times

162
Q

what causes continental drift

A

movements in the mantle cause the plates to move over time

163
Q

when did Pangaea form

A

350 mya

164
Q

what effects did Pangaea have

A

-a deepening of ocean basins
-a reduction in shallow-water habitat
-a colder and drier climate inland

165
Q

what effects does continental drift have on living organisms

A

-Organisms must adapt, move, or risk extinction as the climate changes in response to continents moving toward or away from the equator
-Separation of landmasses can lead to allopatric speciation

166
Q

what is evidence reflects the historic movement of continents

A

the distribution of fossils and living groups

167
Q

The fossil record also shows that most species that have ever lived are now ____

A

extinct

168
Q

Extinction can be caused by changes to a species’ ____ or ____ environment

A

biotic or abiotic

169
Q

At times, the rate of extinction has increased dramatically and caused a ____ ____

A

mass extinction

170
Q

when did the Permian extinction occur

A

between the Paleozoic and Mesozoic Eras 252 mya

171
Q

what factors contributed to the Permian extinction event

A

-extreme volcanism
-global warming and ocean acidification
-anoxic conditions

172
Q

what percentage of the marine animal species went extinct during the Permian extinction

A

96%

173
Q

what caused the cretaceous mass extinction

A

-meteorite impacts the earth
-dust clouds block sunlight and disturb global climate

174
Q

Scientists estimate that the current rate of extinction is ____ to ____ times the typical background rate seen in the fossil record

A

100 to 1,000

175
Q

why are many species declining rapidly

A

-habitat loss
-introduced species
-overharvesting

176
Q

Climate change may ____ declines in species

A

hasten

177
Q

Mass extinctions can change the ____ of organisms found in ecological communities

A

types

178
Q

what is adaptive radiation

A

is the rapid evolution of diversely adapted species from a common ancestor

179
Q

what can cause adaptive radiation

A

-mass extinctions
-the evolution of novel characteristics
-the colonization of new regions (islands)

180
Q

when did mammals undergo an adaptive radiation

A

after the extinction of terrestrial dinosaurs

181
Q

when opened up when the dinosaurs disappeared

A

ecological niches for mammals

182
Q

what allows organisms to adaptive radiate in a new environment

A

when they have little competition

183
Q

Major changes in body form can result from changes in the ____ and ____ of developmental genes

A

sequences and regulation

184
Q

Studying genetic mechanisms of change can provide insight into large-scale ____ ____

A

evolutionary change

185
Q

Genes that program development control the ____, ____, and ____ ____ of changes in an organism’s form as it develops to adulthood

A

rate, timing, and spatial pattern

186
Q

what is heterochrony

A

is an evolutionary change in the rate or timing of developmental events

187
Q

what can heterochrony have an impact on

A

body shape and sexual development

188
Q

what is an example of heterochrony

A

the contrasting shapes of human and chimpanzee skulls

189
Q

what occurs in paedomorphosis

A

the rate of reproductive development accelerates compared with somatic development

190
Q

Substantial evolutionary change can also result from alterations in genes that control the ____ and ____ of body parts

A

placement and organization

191
Q

what do homeotic genes determine

A

basic features as where wings and legs will develop on a bird or how a flower’s parts are arranged

192
Q

what information do Hox genes provide

A

positional information during animal embryonic development

193
Q

what are Hox genes a class of

A

homeotic genes

194
Q

what happens if Hox genes are expressed in the wrong location

A

body parts can be produced in the wrong location

195
Q

what do new morphological forms come from

A

gene duplication events that produce new developmental genes

196
Q

Changes in the ____ of ____ ____ have likely contributed more to changes in the form of organisms than sequence changes

A

regulation of developmental genes

197
Q

what is phylogeny

A

a hypothesis of the evolutionary history of a species or group of related species

198
Q

what discipline classifies organisms and determines their evolutionary relationships

A

systematics

199
Q

what shows evolutionary relationships

A

phylogenies

200
Q

The two-part scientific name of a species is called a ____

A

binomial

201
Q

what is the first part of a scientific name

A

genus

202
Q

what is the second part of a scientific name

A

specific epithet

203
Q

what are the taxonomic groups

A

-domain
-kingdom
-phylum
-class
-order
-family
-genus
-species

204
Q

A taxonomic unit at any level of hierarchy is called a ____

A

taxon

205
Q

The broader taxa (i.e. the number of species) are not always ____ between lineages

A

comparable

206
Q

The evolutionary history of a group of organisms can be represented in a branching ____ ____

A

phylogenetic tree

207
Q

what does each branch point on a phylogenetic tree represent

A

represents the divergence of two evolutionary lineages from a common ancestor

208
Q

what are sister taxa

A

groups that share an immediate common ancestor that is not shared by any other group

209
Q

A ____ tree includes a branch to represent the most recent common ancestor of all taxa in the tree

A

rooted

210
Q

A ____ ____ diverges early in the history of a group and originates near the common ancestor of the group

A

basal taxon

211
Q

what do phylogenetic trees show

A

patterns of descent

212
Q

do phylogenetic trees show phenotypic similarity

A

no

213
Q

do phylogenetic trees indicate when species evolve or how much change occurred in a lineage

A

no

214
Q

To infer phylogenies, systematists gather information about the ____, ____, and ____ of living organisms

A

morphologies, genes, and biochemistry

215
Q

Phenotypic and genetic similarities due to shared ancestry are called ____

A

homologies

216
Q

Organisms with similar ____ or ____ ____ are likely to be more closely related than organisms with different structures or sequences

A

morphologies or DNA sequences

217
Q

When constructing a phylogeny, systematists need to distinguish whether a similarity is the result of ____ or ____

A

homology or analogy

218
Q

what causes a homology

A

shared anacestry

219
Q

what causes analogy

A

convergent evolution

220
Q

what does convergent evolution occur

A

similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages

221
Q

how can homology be distinguished from analogy

A

-comparing fossil evidence and degree of complexity
-Comparing genes in two organisms that share nucleotide sequence (bioinformatics)
-The more elements that are similar in two complex structures, the more likely it is that they are homologous

222
Q

what are homoplasies

A

coincidental similarities

223
Q

Shared ____ are used to construct phylogenetic trees

A

characters

224
Q

Once ____ ____ have been identified, they can be used to infer a phylogeny

A

homologous characters

225
Q

what are cladistics

A

an approach to grouping organisms (classification) by common ancestry

226
Q

what is a clade

A

is a group of species that includes an ancestral species and all its descendants

227
Q

what is a valid clade

A

if it is monophyletic

228
Q

what does monophyletic signify consist of

A

that it consists of the ancestor species and all its descendants

229
Q

what are the invalid groupings of clades

A

-paraphyletic
-polyphyletic

230
Q

what does a paraphyletic grouping consist of

A

an ancestral species and some, but not all, of the descendants

231
Q

what does a polyphyletic grouping consist of

A

distantly related species but does not include their most recent common ancestor

232
Q

how are polyphyletic groups distinguished from paraphyletic groups

A

by the fact that they do not include the most recent common ancestor

233
Q

what is a shared ancestral character

A

is a character that originated in an ancestor of the taxon

234
Q

what is a derived character

A

is an evolutionary novelty unique to a particular clade

235
Q

can a character be both ancestral and derived

A

yes

236
Q

what is an outgroup

A

is a species or group of species that is closely related to the ingroup

237
Q

what is an ingroup

A

the various species being studied

238
Q

did the outgroup or ingroup diverge first

A

outgroup

239
Q

Systematists compare each ingroup species with the outgroup to differentiate between shared ____ and shared ____ characters

A

derived, ancestral

240
Q

what does maximum parsimony assume

A

assumes the most likely tree is one that requires the fewest evolutionary events (appearances of shared derived characters)

241
Q

what does maximum likelihood use

A

using probability rules about how DNA changes over time to develop a tree that reflects the most likely sequence of evolutionary events

242
Q

how do systematists narrow the possibilities of finding the best tree in a large data set

A

applying the principles of maximum parsimony and maximum likelihood

243
Q

The best hypothesis for a phylogenetic tree fits the most data: ____, ____, and ____

A

morphological, molecular, and fossil

244
Q

what features do birds and crocodiles share

A

four-chambered hearts, song, nest building, and brooding

245
Q

The ____ ____ supports nest building and brooding in dinosaurs

A

fossil record

246
Q

what did the features shared by birds and crocodiles evolve from

A

a common ancestor

247
Q

Comparing ____ ____ or other ____ to infer relatedness is a valuable approach for tracing organisms’ evolutionary history

A

nucleic acids, molecules

248
Q

what is useful for investigating branching points that diverged hundreds of millions of years ago

A

DNA that codes for rRNA

249
Q

what can be used to explore recent evolutionary events

A

mtDNA

250
Q

An organism’s evolutionary history is documented in its ____

A

genome

251
Q

____ _____ increases the number of genes in the genome, providing more opportunities for evolutionary changes

A

Gene duplication

252
Q

Repeated gene duplications result in ____ ____

A

gene families

253
Q

Like homologous genes, duplicated genes can be traced to a ____ _____

A

common ancestor

254
Q

where are orthologous genes found

A

in a single copy of a gene in the genome

255
Q

are orthologous genes homologous between species

A

yes

256
Q

when can orthologous genes diverge

A

after speciation occurs

257
Q

what do paralogous genes result from

A

gene duplication

258
Q

are paralogous genes found in more than one copy in the genome

A

yes

259
Q

Paralogous genes can diverge within the species that carries them and often evolve ____ ____

A

new functions

260
Q

____ genes are widespread and extend across many widely varied species

A

Orthologous

261
Q

are gene number and the complexity of an organism strongly or not strongly linked

A

not strongly linked

262
Q

Genes in complex organisms appear to be very versatile, and each ____ can encode multiple ____ that perform many different functions

A

gene, proteins

263
Q

A molecular clock uses constant rates of evolution in some genes to estimate what

A

the absolute time of evolutionary change

264
Q

in which genes are nucleotide substitutions are assumed to be proportional to the time since they last shared a common ancestor

A

orthologous

265
Q

in which genes are nucleotide substitutions are proportional to the time since the genes became duplicated

A

paralogous

266
Q

what are molecular clocks calibrated against

A

branches whose dates are known from the fossil record

267
Q

If most of the evolutionary change in genes and proteins has no effect on fitness, then the rate of molecular change should be ____

A

regular

268
Q

Differences in clock rate for different genes are a function of what

A

-the importance of the gene
-how critical the specific amino acid is to protein function

269
Q

The molecular clock does not run as smoothly as expected if ____ were ____

A

mutations, neutral

270
Q

how do irregularities result from natural selection

A

some DNA changes are favored over others

271
Q

Dating the Origin of HIV

A

-Phylogenetic analysis shows that HIV is descended from viruses that infect chimpanzees and other primates
–HIV spread to humans more than once
–Comparison of HIV samples shows that the virus evolved in a very clocklike way
–The earliest sample of HIV (fragments) is a 1959 blood sample from Kinshasa, Democratic Republic of the Congo
-Application of a molecular clock to one strain of HIV suggests that the strain spread to humans during the 1930s
-A more advanced molecular clock approach estimated the first spread to humans around 1910

272
Q

what are the three domains

A

bacteria, Archaea, and Eukarya

273
Q

what did early taxonomists classify all species as

A

either plants or animals

274
Q

what are the five kingdoms that are recognized

A

Monera (prokaryotes), Protista, Plantae, Fungi, and Animalia

275
Q

what is polytomy

A

an internal node of a phylogenetic tree linked to three or more child subtrees

276
Q

which domains are more closely related

A

eukaryotes and archaea are more closely related to each other than to bacteria

277
Q

what is the tree of life based largely on

A

rRNA genes

278
Q

what is horizontal gene transfer (HGT)

A

is the movement of genes from one genome to another

279
Q

how does HGT (horizontal gene transfer) occur

A

by exchange of: transposable elements, plasmids, viral infection, and possibly fusion of organisms

280
Q

how can differences between gene trees be explained

A

by the occurrence of horizontal gene transfer

281
Q

____ ____ ____ has played a key role in the evolution of both prokaryotes and eukaryotes

A

Horizontal gene transfer

282
Q

Eukaryotes can acquire nuclear genes from ____ and ____

A

bacteria and archaea

Ecology (5 decks)

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