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Ecology > Ecology Exam 3 (Chapters 22-23) > Flashcards

Ecology Exam 3 (Chapters 22-23) Flashcards

1
Q

A new era of biology began in 1859 when ____ published ____

A

Charles Darwin published The Origin of Species

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2
Q

The Origin of Species focused biologists’ attention on the great ____ of organisms

A

diversity

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3
Q

Darwin noted that current species are descendants of ____ species

A

ancestral

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4
Q

Evolution can be viewed as both a ____ and a ____

A

pattern, process

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5
Q

how can evolution be defined

A

descent with modification

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6
Q

what are the two types of evolution

A

marco and micro

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7
Q

what did Jean-Baptiste de Lamarck hypothesize about how species evolve

A

that species evolve through use and disuse of body parts and the inheritance of acquired characteristics

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8
Q

what is an example of Jean-Baptiste de Lamarck’s hypothesis of species evolution

A

a giraffe stretches is neck and so its offspring will have longer necks

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9
Q

when did Darwin travel around the world on the HMS Beagle

A

1831-1836

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10
Q

when was the Origin of Species published

A

1859

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11
Q

The Greek philosopher Aristotle viewed species as ____ and arranged them on a ____

A

fixed, scala naturae

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12
Q

What is Carolus Linnaeus the founder of

A

taxonomy, naming of species

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13
Q

what is taxonomy

A

the branch of biology concerned with classifying organisms

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14
Q

The study of ____ helped to lay the groundwork for Darwin’s ideas

A

fossils

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15
Q

what layer of the earth are fossils found in

A

the strata

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16
Q

what is Paleontology

A

the study of fossils

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17
Q

why did Darwin consider the fossil record to be highly unreliable

A

-Many places on the earth had not been prospected for fossils.
-Only some types of organisms form well preserved fossils.
-More species have lived than have been discovered as fossils.
-Fossilization is a difficult process, so the fossil record will be full of holes.
-Because organisms migrate, you will not get a continuous record of fossilized species in a single location.

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18
Q

The fossil record is one of the direct lines of evidence to support the ____

A

evolutionary theory

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19
Q

should the fossils found in the youngest or oldest layers of rock look more like the organisms that exist today

A

youngest

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20
Q

what does each layer of sedimentary rock represent

A

a period of geologic time

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21
Q

once a species goes extinct will it reappear in the fossil record

A

no

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22
Q

what are transitional fossils

A

are fossils that appear to be transitional forms between two distinct large taxa

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23
Q

what is an example of a transitional fossil

A

Archaeopteryx siemensii

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24
Q

what idea formed from Darwin’s ideas in social and political arenas

A

Social Darwinism

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25
Q

what did Social Darwinism argue

A

the unfit” of human society should be eliminated for the good of the human race

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26
Q

what is another name for Social Darwinism

A

Eugenics

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27
Q

what was eugenics used to validate

A

validate racism, and mistreatment of the impoverished and mentally ill.

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28
Q

____ by ____ explains the adaptations of organisms and the unity and diversity of life

A

descent with modification by natural selection

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29
Q

what did Darwin note about the fossils that he found

A

fossils resembled living species from the area in which they were found

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30
Q

he noted that living species ____ other species from areas nearby

A

resembled

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31
Q

Darwin hypothesized that species from the mainland ____ and then ____ on the islands

A

colonized, diversified

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32
Q

what are adaptations

A

are inherited characteristics that enhance an organism’s survival and reproduction in specific environments

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33
Q

what has given rise to the diversity of life

A

descent with modification

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34
Q

what is natural selection

A

is a process in which individuals with certain inherited traits tend to survive and reproduce at higher rates because of those traits

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35
Q

species accumulate differences from their ancestors as they adapt to different ____ over many generations

A

environments

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36
Q

Darwin proposed ____ as an explanation for adaptation

A

natural selection

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37
Q

In reassessing his observations, Darwin perceived adaptation to the ____ and the origin of ____ as closely related processes

A

environment, new species

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38
Q

what is the mechanism of descent with modification

A

natural selection

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39
Q

what are Darwin’s three broad observations from the Origin of Species

A

-The unity of life
-The diversity of life
-The ways organisms are suited to life in their environments

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40
Q

The phrase ____ summarized Darwin’s perception of the unity of life

A

descent with modification

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41
Q

True/False. Darwin used the word evolution in his book the Origin of Species

A

False

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42
Q

what is the Darwinian view of the history of life

A

the history of life is like a tree with branches representing life’s diversity

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43
Q

how are large morphological gaps between related groups explained

A

by the branching process and past extinction events

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44
Q

what is artificial selection

A

humans have modified other species by selecting and breeding individuals with desired traits

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45
Q

what were Darwin’s two observations

A
  1. Members of a population often vary in their inherited traits
  2. All species can produce more offspring than the environment can support, and many of these offspring fail to survive and reproduce
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46
Q

what did Thomas Malthus note

A

the potential for the human population to increase faster than food supplies and other resources

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47
Q

if individuals with advantageous heritable traits produce more offspring that survive to reproduce, how will this affect the frequency of this trait

A

the trait will increase in frequency in the next generation

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48
Q

what two Inferences did Darwin make

A
  1. Individuals that are well suited
    to their environment tend to leave more
    offspring than other individuals.
  2. Over time, favorable traits
    accumulate in the population
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49
Q

what are the key features of natural selection

A

-Individuals with certain heritable traits survive and reproduce at a higher rate than other individuals
-Natural selection increases the frequency of adaptations that are favorable in a given environment

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50
Q

If an environment changes over time, natural selection may result in adaptation to these new conditions and may give rise to ____

A

new species

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51
Q

Individuals ____ evolve; ____evolve over time

A

do not, populations

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52
Q

Natural selection can only increase or decrease ____ that vary in a population

A

heritable traits

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53
Q

does natural selection create new traits

A

no, the trait must already be present

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54
Q

Adaptations vary with different ____

A

environments

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55
Q

what are the four types of evidence that document the pattern of evolution

A
  1. Direct observations
  2. Homology (DNA evidence)
  3. The fossil record
  4. Biogeography
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56
Q

what two examples provide evidence for natural selection

A

-natural selection in response to introduced species
-the evolution of drug-resistant bacteria

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57
Q

what is an example of natural selection in response to introduced species

A

-Soapberry bugs use their “beak” to feed on seeds within fruits
-Feeding is most effective when beak length is closely matched to seed depth within the fruit

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58
Q

in southern Florida, soapberry bugs feed on the native balloon vine with larger fruit; this leads to ____

A

longer beaks

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59
Q

In central Florida, they feed on the introduced goldenrain tree with smaller fruit; this leads to ____

A

shorter beaks

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60
Q

what is an example of evolution of drug-resistant bacteria

A

-Resistance to penicillin evolved in S. aureus by 1945, two years after it was first widely used
-Resistance to methicillin evolved in S. aureus by 1961, two years after it was first widely used
-When exposed to methicillin, MRSA strains are more likely to survive and reproduce than nonresistant S. aureus strains
-MRSA strains are now resistant to many antibiotics

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61
Q

Natural selection does not create ____ traits, but ____ or ____ for traits already present in the population

A

new, edits or selects

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62
Q

Evolution by natural selection can occur rapidly in species with ____ generation times

A

short

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63
Q

the current, local ____ determines which traits will be selected for or selected against in any specific population

A

environment

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64
Q

what is homology

A

similarity resulting from common ancestry

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65
Q

what are homologous structures

A

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

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66
Q

what are examples of homologous structures

A

the bones in the forelimbs of humans, cats, whales, bats

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67
Q

Comparative ____ reveals anatomical homologies ____ in adult organisms

A

embryology, not visible

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68
Q

what is an example of comparative embryology

A

all vertebrate embryos have a post-anal tail and pharyngeal arches

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69
Q

what are vestigial structures

A

are remnants of features that served a function in the organism’s ancestors

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70
Q

what are examples of homologies at the molecular level

A

are genes shared among organisms inherited from a common ancestor

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71
Q

what are evolutionary trees

A

are diagrams that reflect hypotheses about the relationships among different groups

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72
Q

Homologies form ____ patterns in evolutionary trees

A

nested

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73
Q

Evolutionary trees can be made using different types of data, for example, ____ and ____ data

A

anatomical and DNA sequence

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74
Q

what is convergent evolution

A

is the evolution of similar, or analogous, features in distantly related groups

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75
Q

Analogous traits arise when groups ____ to similar environments in similar ways

A

independently adpat

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76
Q

what is an example of convergent evolution

A

types of wings, birds vs. bats

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77
Q

what does the fossil record provide evidence for

A

-the extinction of species
-the origin of new groups
-and changes within groups over time

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78
Q

Fossils can document important ____

A

transitions

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79
Q

what is biogeography

A

the scientific study of the geographic distribution of species, provides evidence of evolution

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80
Q

what was Pangaea

A

Earth’s continents were formerly united in a single large continent

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81
Q

what is the term for continents drifting apart

A

continental drift

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82
Q

what does a understanding of continent movement and modern distribution of species allow us to predict

A

when and where different groups evolved

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83
Q

what is evidence that points to the existence of Pangaea

A

The distribution of fossils across the continents

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84
Q

what are endemic species

A

are species that are not found anywhere else in the world

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85
Q

Islands have many endemic species that are often closely related to species on the nearest ____ or ____

A

mainland or island

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86
Q

what is genomics the study of

A

of whole sets of genes and their interactions

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87
Q

what was the goal of the human genome project

A

is to determine the complete nucleotide sequence of each chromosome

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88
Q

how was the human genome project completed

A

using sequencing machines and the dideoxy chain termination method

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89
Q

what two approaches were used to obtain the complete sequence

A

-fragment based mapping & sequencing
-whole-genome shotgun approach

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90
Q

The basis of change at the genomic level is ____, which underlies much of genome evolution

A

mutation

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91
Q

____, ____, and ____ of DNA contribute to genome evolution

A

duplication, rearrangement, and mutation

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92
Q

The earliest forms of life likely had only those genes necessary for ____ and ____

A

survival and reproduction

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93
Q

The size of genomes has ____ over evolutionary time, with the extra genetic material providing ___ for gene diversification

A

increased, raw material

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94
Q

Accidents in meiosis can lead to one or more ____, a condition known as polyploidy

A

extra sets of chromosomes

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95
Q

what is polyploidy

A

when you have extra sets of chromosomes

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96
Q

The genes in one or more of the extra sets of chromosomes can diverge by ____

A

accumulating mutations

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97
Q

These variations in genes may persist if the organism carrying them ____ and ____

A

survives and reproduces

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98
Q

how many pairs of chromosomes do humans have

A

23

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99
Q

Following the divergence of humans and chimpanzees from a common ancestor, two ancestral chromosomes ____ in the human line

A

fused

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100
Q

Large blocks of genes on human chromosome 16 are found on four ____ chromosomes

A

mouse

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101
Q

when genes are found in both humans and mice what does that indicate for the genes on that block

A

This indicates that the genes in each block stayed together in both the human and mouse lineages

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102
Q

____ are thought to contribute to the generation of new species

A

chromosomal rearrangements

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103
Q

what is the history of chromosomal evolution

A

-The rate of duplications and inversions seems to have accelerated about 100 million years ago
-This coincides with when large dinosaurs went extinct and mammals diversified

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104
Q

what is unequal crossing

A

over during prophase I of meiosis can result in one chromosome with a deletion and another with a duplication of a particular region

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105
Q

____ elements can provide sites for crossover between nonsister chromatids

A

transposable

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106
Q

Also, ____ can occur during ____ so that a part of the template is either skipped, or replicated twice

A

slippage, DNA replication

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107
Q

Evidence suggests that the genes encoding the ____ evolved from one common ancestral globin gene, which duplicated and diverged about 450–500 million years ago

A

globin proteins

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108
Q

After the duplication events, differences between the genes in the globin family arose from the ____ of ____

A

accumulation of mutations

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109
Q

what are the types of globin

A

hemoglobin (12), myoglobin, cytoglobin, neuroglobin

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110
Q

subsequent ____ and random ____ gave rise to the present globin genes, which code for oxygen-binding proteins

A

duplications, mutations

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111
Q

One copy of a ____ can undergo alterations that lead to a completely new ____ for the protein product

A

duplicated gene, function

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112
Q

the lysozyme gene duplicated and evolved into what gene

A

encodes α-lactalbumin in mammals

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113
Q

____ is an enzyme that helps protect animals against bacterial infection

A

lysozyme

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114
Q

α-lactalbumin is a ____ protein that plays a role in milk production in mammals

A

nonenzymatic

115
Q

Errors in meiosis can result in an exon being ____ on one chromosome and ____ from the homologous chromosome

A

duplicated, deleted

116
Q

In exon shuffling, errors in meiotic recombination lead to some ____ and ____ of exons, either within a gene or between two nonallelic genes

A

mixing and matching

117
Q

The current version of the gene for tissue plasminogen activator (TPA) is thought to have arisen by several instances of ____ shuffling and ____ duplication

A

exon and subsequent

118
Q

transposable elements carry a ____ or groups of ____ to a new position

A

gene, genes

119
Q

transposable elements create ____ sites for ____ in an RNA transcript

A

new, alternative splicing

120
Q

Insertion of transposable elements within a regulatory sequence ____ or ____ protein production = regulation

A

increase or decrease

121
Q

Multiple copies of similar transposable elements facilitate ____, or ____ between different chromosomes

A

recombination, or crossing over

122
Q

Insertion of transposable elements within a protein-coding sequence may block ____

A

protein production

123
Q

are changes in the gene sequence usually detrimental or advantageous

A

detrimental

124
Q

Comparing genome sequences provides clues to ____ and ____

A

evolution and development

125
Q

Comparisons of genome sequences from different species reveals____

A

evolutionary history of life

126
Q

Comparative studies of genetic programs that affect ____ development are beginning to clarify the mechanisms that generated the diversity of life-forms present today.

A

embryonic

127
Q

Genome comparisons of closely related species help shed light on recent ____ events

A

evolutionary

128
Q

Comparing genomes of very distantly related species helps us understand ____ evolutionary history

A

ancient

129
Q

Relationships among species can be represented by a____-shaped diagram

A

tree

130
Q

Highly conserved genes have changed ____ over time

A

very little

131
Q

what do highly conserved genes clarify between species that diverged from each other long ago

A

relationships

132
Q

can very ancient genes still be surprisingly similar in disparate species

A

yes

133
Q

Genomes of closely related species are likely to be organized ____

A

similarly

134
Q

For example, comparison of the ____ with other ____ gives us clues about what it takes to make a mammal

A

human genome, mammals

135
Q

Analysis of the ____ and ____ genomes reveals some general differences that underlie the differences between the two organisms

A

human and chimpanzee

136
Q

do we know how the genetic differences revealed by genome sequencing account for the distinct characteristics of each species

A

no

137
Q

did genes evolve faster in the human or chimpanzee or the mouse

A

human

138
Q

what genes evolved faster in humans than chimpanzees or mice

A

genes involved in defense against malaria and tuberculosis and one that regulates brain size

139
Q

what gene shows evidence of rapid change in the human lineage compared to other primates

A

FOXP2

140
Q

what might the FOXP2 gene be related to

A

human speech

141
Q

how many amino acids are only found in the human protein sequence

A

two

142
Q

what does the mutation of the FOXP2 lead to in humans

A

severe speech and language impairment in humans

143
Q

when the FOXP2 is removed from mice have the human form of the gene introduced can the mice vocalize

A

yes, and they are healthy

144
Q

are the mice that have the human FOXP2 have different vocalizations than they did before

A

yes

145
Q

do humans have high or low within-species genetic variation

A

low

146
Q

what are the three ways that the human genome can have variations

A

inversions, deletions and duplications

147
Q

Variation within humans is due to ____

A

single nucleotide polymorphisms

148
Q

what role do copy-number variants of the human genome play

A

complex diseases and disorders

149
Q

____, ____, and other ____ are useful genetic markers for studying human evolution

A

Copy-number variants, SNPs, and other polymorphisms

150
Q

what are SNPS

A

inversions, deletions, and duplications

151
Q

what genome has the highest genetic diversity

A

african

152
Q

what does is suggest when a population has higher genetic diversity

A

the population has been evolving longer

153
Q

Evolutionary developmental biology, or evo-devo, compares ____ processes of different multicellular organisms

A

developmental

154
Q

Genomic information shows that ____ differences in gene sequence or regulation can result in striking ____ in form

A

minor, differences

155
Q

what is a homeobox

A

a 180-nucleotide sequence contained within a gene

156
Q

what are homeotic genes in animals called

A

Hox genes

157
Q

The ____ is the part of the protein that binds to the DNA, where the protein functions as a transcription factor

A

homeodomain

158
Q

In addition to homeotic genes, many other developmental genes are highly ____ from species to species

A

conserved

159
Q

Sometimes small changes in ____ of certain genes lead to major changes in body form

A

regulatory sequences

160
Q

For example, variation in Hox gene expression controls ____ in leg-bearing segments of crustaceans and insects

A

variation

161
Q

In other cases, genes with conserved sequences play ____ in different species

A

different roles

162
Q

True/False do individual organisms evolve

A

False

163
Q

Natural selection acts on ____, but only ____ evolve

A

individuals, populations

164
Q

what is microevolution

A

is a change in allele frequencies within a population over generations

165
Q

what is an allele

A

alternative form of a gene

166
Q

what are the three main mechanisms that cause allele frequency change

A

-Natural selection
-Genetic drift
-Gene flow

167
Q

Only ____ consistently causes adaptive evolution

A

natural selection

168
Q

____ makes evolution possible

A

genetic variation

169
Q

____ in heritable traits is a prerequisite for evolution by ____

A

variation, natural selection

170
Q

whose work provided evidence of discrete heritable units (genes)

A

Gregor Mendel

171
Q

what causes genetic varitation

A

differences in genes or other DNA segments

172
Q

____ is the product of inherited genotype and environmental influences

A

Phenotype

173
Q

Natural selection can only act on variation with a ____ component

A

genetic

174
Q

Some phenotypic differences are determined by a ____ and can be classified on an “either-or” basis

A

single gene

175
Q

Other phenotypic differences are determined by the influence of two or more genes and vary along a ____ within a population

A

continuum

176
Q

are phenotypic differences determined by one gene or more than one

A

it can be either

177
Q

what is it called when a phenotypic difference is determined by two or more genes

A

multigenic traits

178
Q

what are three examples of multigenic traits

A

-height
-weight
-skin color

179
Q

Genetic variation can be measured as ____ variability or ____ variability

A

gene or nucleotide

180
Q

for gene variability, average heterozygosity measures what

A

the average percent of loci that are heterozygous in a population

181
Q

Nucleotide variability is measured by comparing the ____ of two or more individuals

A

DNA sequences

182
Q

Nucleotide variation rarely results in ____ variation

A

phenotypic

183
Q

where do most differences in nucleotide variation occur

A

noncoding regions (introns)

184
Q

what do variations that occur in coding regions (exons) rarely change

A

the amino acid sequence of the encoded protein

185
Q

Some phenotypic variation does not result from genetic differences among individuals, but rather from ____ influences

A

environmental

186
Q

Only genetically determined variation can have ____ consequences

A

evolutionary

187
Q

New genes and alleles can arise by ____ or ____

A

mutation or gene duplication

188
Q

Sexual reproduction can result in genetic variation by ____ existing alleles

A

recombining

189
Q

how do you get new genes

A

crossing over between two transposons

190
Q

what do new alleles arise from

A

New alleles arise by mutation, a change in the nucleotide sequence of DNA

191
Q

what is a point mutation

A

is a change in a single nucleotide in a DNA sequence

192
Q

Only mutations in cells that produce ____ can be passed to offspring

A

gametes

193
Q

Mutations that alter the phenotype are often ____

A

harmful

194
Q

Harmful mutations can be hidden from selection in ____

A

recessive alleles

195
Q

are mutations that results in a change in phenotype ever beneficial

A

rarely

196
Q

Point mutations in noncoding regions generally result in ____

A

neutral variation

197
Q

what is neutral variation

A

conferring no selective advantage or disadvantage

198
Q

when can mutations to genes be neutral

A

redundancy in the genetic code

199
Q

Chromosomal mutations that ____, ____, or ____ many loci are typically harmful

A

delete, disrupt, or rearrange

200
Q

Duplication of small pieces of DNA increases ____ and is usually ____ harmful

A

genome size, less

201
Q

can duplicated genes take on new functions by further mutation

A

yes

202
Q

Mutation rates are ____ in animals and plants

A

low

203
Q

Mutation rates are often lower in ____

A

prokaryotes

204
Q

short generation times allow mutations to accumulate ____

A

rapidly

205
Q

____ have both high mutation rates and short generation times

A

Viruses

206
Q

In organisms that reproduce sexually, most genetic variation results from ____ of alleles

A

recombination

207
Q

what are the three mechanisms that sexual reproduction can shuffle existing alleles into new combinations

A

-crossing over,
-independent assortment
-fertilization

208
Q

what is the Hardy-Weinberg equation used to test for

A

whether a population is evolving

209
Q

____ is required for a population to evolve

A

Genetic variation

210
Q

does genetic variation guarantee that a population will evolve

A

no

211
Q

____ or ____ factors that cause evolution must be at work for a population to evolve

A

One or more

212
Q

A ____ is a localized group of individuals capable of interbreeding and producing fertile offspring

A

population

213
Q

individuals typically only breed with members of their ____ population

A

own

214
Q

what does a gene pool consist of

A

consists of all the alleles for all loci in a population

215
Q

A locus is ____ if all individuals in a population are ____ for the same allele

A

fixed, homozygous

216
Q

If there are two or more alleles for a locus, diploid individuals may be either ____ or ____

A

homozygous, heterozygous

217
Q

what is the condition to sustain a population with H-W equilibrium

A

allele and genotype frequencies remain constant from generation to generation

218
Q

Hardy-Weinberg equilibrium describes the constant frequency of _____ in such a gene pool

A

alleles

219
Q

does the Hardy-Weinburg approach describe a population that is not evolving

A

yes

220
Q

what are the conditions of the Hardy-Weinburg Equilibrium

A

-no mutations
-random mating
-no natural selection
-extremely large population size
-no gene flow

221
Q

The Hardy-Weinberg equation can be used to test whether ____ is occurring in a population

A

evolution

222
Q

The Hardy-Weinburg equation is also used to determine the percentage of a population carrying a ____

A

specific allele

223
Q

what is the consequence if the condition of “no mutations” for H-W isn’t upheld

A

The gene pool is modified if mutation occur or if the entire genes are deleted or duplicated

224
Q

what is the consequence if the condition of “random mating” for H-W isn’t upheld

A

if individuals mate within a subset of the population, such as near neighbors or close relatives (inbreeding), random mixing of gametes does not occur and genotype frequencies change

225
Q

what is the consequence if the condition of “no natural selection” for H-W isn’t upheld

A

allele frequencies change when individuals with different genotypes show consistent differences in their survival or reproductive success

226
Q

what is the consequence if the condition of “extremely large population size” for H-W isn’t upheld

A

in small populations, allele frequencies fluctuate by chance over time (a process called genetic drift)

227
Q

what is the consequence if the condition of “no gene flow” for H-W isn’t upheld

A

by moving alleles into or out of populations, gene flow can alter allele frequencies

228
Q

what are the three major factors that alter allele frequencies and bring about the most evolutionary change

A

-natural selection
-genetic drift
-genetic flow

229
Q

what is fitness

A

reproductive success

230
Q

If ____ is taking place, it results in alleles being passed to the next generation in ____ that differ from those in the present generation

A

selection, proportions

231
Q

Natural selection ____ cause adaptive evolution

A

can

232
Q

what is adaptive evolution

A

a process in which traits that enhance survival or reproduction increase in frequency over time.

233
Q

what does genetic drift describe

A

describes how allele frequencies fluctuate unpredictably from one generation to the next

234
Q

The ____ a sample (or the ____ the population), the ____ the chance of random deviation from a predicted result

A

smaller, smaller, greater

235
Q

how does genetic drift reduce genetic variation

A

random loss of alleles

236
Q

what are the two types of genetic drift

A

-founder effect
-bottleneck effect

237
Q

how does the founder effect occur

A

when a few individuals become isolated from a larger population

238
Q

Allele frequencies in the ____ population can be different from those in the larger parent population

A

small founder

239
Q

when does the bottleneck effect occur

A

when there is a drastic reduction in population size due to a sudden change in the environment

240
Q

what is the effect of the bottleneck effect

A

The resulting gene pool may no longer be reflective of the original population’s gene pool

241
Q

If the population remains ____, it may be further affected by genetic drift

A

small

242
Q

discuss the Case Study: Impact of Genetic Drift on the Greater Prairie Chicken

A

-Loss of prairie habitat caused a severe reduction in the population of greater prairie chickens in Illinois
-The surviving birds had low levels of genetic variation, and only 50% of their eggs hatched
-Researchers used DNA from museum specimens to compare genetic variation in the population before and after the bottleneck
-The results showed a loss of alleles at several loci
-Researchers introduced greater prairie chickens from populations in other states and were successful in introducing new alleles and increasing the egg hatch rate to 90%

243
Q

list the four effects of genetic drift

A

-Genetic drift is significant in small populations
-Genetic drift can cause allele frequencies to change at random
-Genetic drift can lead to a loss of genetic variation within populations (founder or bottleneck effects)
-Genetic drift can cause harmful alleles to become fixed

244
Q

what does gene flow consist of

A

the movement of alleles among populations

245
Q

how can alleles be transferred

A

through the movement of fertile individuals or gametes

246
Q

Gene flow tends to ____ variation among populations over time (but not always)

A

reduce

247
Q

Gene flow can affect ____ to local environments

A

adaptation

248
Q

Gene flow can ____ the fitness of a population

A

increase

249
Q

what is an example of gene flow increasing the fitness of a population

A

resistance to insecticides

250
Q

____ is an important agent of evolutionary change in modern human populations

A

Gene flow

251
Q

Natural selection is the only mechanism that consistently causes ____ evolution

A

adaptive

252
Q

Evolution by natural selection involves both ____ and ____

A

chance, sorting

253
Q

New genetic variations arise by ____

A

chance

254
Q

Beneficial alleles are ____ and favored by natural selection

A

sorted

255
Q

Only ____ consistently increases the frequencies of alleles that provide reproductive advantage

A

natural selection

256
Q

Natural selection brings about adaptive evolution by acting on an organism’s ____

A

phenotype

257
Q

what is relative fitness

A

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

258
Q

Selection favors certain ____ by acting on the ____ of individuals

A

genotypes, phenotypes

259
Q

what are the three modes of selection

A

-directional
-disruptive
-stabilizing

260
Q

what does directional selection favor

A

individuals at one extreme end of the phenotypic range

261
Q

what does disruptive selection favor

A

individuals at both extremes of the phenotypic range

262
Q

what does stabilizing selection favor

A

favors intermediate variants and acts against extreme phenotypes

263
Q

Natural selection increases the frequencies of ____ that enhance ____ and ____

A

alleles, survival, reproduction

264
Q

____ evolution occurs as the degree to which a species is well suited for life in its environment improves

A

adaptive

265
Q

Because the environment can change, adaptive evolution is a ____ process

A

continuous

266
Q

Genetic drift and gene flow do not consistently ____ the frequency of alleles that enhance survival and reproduction

A

increase

267
Q

Both genetic drift and gene flow may ____ or ____ the frequency of beneficial alleles in a population

A

increase or decrease

268
Q

what is sexual selection

A

is a process in which individuals with certain inherited characteristics are more likely to acquire mates than other individuals of the same sex

269
Q

what can sexual selection result in

A

sexual dimorphism

270
Q

what is sexual dimorphism

A

marked differences between the sexes in secondary sexual characteristics

271
Q

what is intrasexual selection

A

is direct competition among individuals of one sex (often males) for mates of the opposite sex

272
Q

what is intersexual selection

A

often called mate choice, occurs when individuals of one sex (often females) are choosy in selecting their mates

273
Q

Showiness of male appearance can ____ a male’s chances of attracting a female while ____ his chances of survival

A

increase, decreasing

274
Q

which type of sexual selection has males being brightly colored

A

intersexual selection

275
Q

how does diploidy maintain genetic variation

A

in the form of recessive alleles hidden from selection in heterozygotes

276
Q

when does balancing selection occur

A

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

277
Q

what does balancing selection include

A

-Frequency-dependent selection
-Heterozygote advantage

278
Q

In frequency-dependent selection, the fitness of a phenotype depends on ____ it is in the population

A

how common

279
Q

what is an example of frequency-dependent selection

A

right-mouthed and left-mouthed scale eating fish

280
Q

when does heterozygote advantage occur

A

when heterozygotes have a higher fitness than both homozygotes

281
Q

Natural selection will tend to maintain ____ or ____ alleles at that locus

A

two or more

282
Q

Heterozygote advantage can result from ____ or ____ selection

A

stabilizing or directional

283
Q

what is an example of a heterozygote advantage

A

sickle cell anemia

284
Q

list the four reasons why natural selection cannot fashion perfect organisms

A

-Selection can act only on existing variations
-Evolution is limited by historical constraints
-Adaptations are often compromises
-Chance, natural selection, and the environment interact

Ecology (5 decks)

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