Eemb 2 Final Flashcards
(193 cards)
1
Q
General definition of evolution that Darwin would recognize
A
descent with modification
2
Q
Darwin vs Lamarck’s Theory
A
Lamarck’s Theory—> individuals change
Darwin’s Theory—> populations change
3
Q
Darwin’s Theory and Observations
A
artificial selection (individuals in population vary in heritable characteristics) + organisms produce more than the environment can sustain (Malthus) –> better suited individuals give rise to more successful offspring (lamark)–> favorable traits accumulate in population (lyell)
4
Q
Lyell and Malthus
A
Principle of Geology (Lyell) —> suggests that Earth’s features were shaped by slow, gradual processes.
Principle of Population (Malthus) —> natural populations tend to grow faster than their food supply.
5
Q
Principal problem that Darwin could not explain
A
blending inheritance pattern (enter mendelian genetics)
6
Q
Allele frequency
A
The proportion of a specific allele within a gene’s population
7
Q
Allele
A
Alternate version of a gene
8
Q
Gene pool
A
The proportion of a specific allele within a gene’s population
9
Q
Genome
A
entirety of genetic material of organism
10
Q
Gene
A
Discrete unit of hereditary information
11
Q
Genotype
A
Genetic makeup of an organism
12
Q
Hardy-Weinberg Principle
A
Allele frequencies in a population will not change from generation to generation
13
Q
Define microevolution in terms of alleles and the gene pool
A
A change in the allele frequencies in a population
14
Q
New Synthesis
A
the discovery of genetics and hereditary blending in evolution
15
Q
Phenotype
A
Observable traits of an organism which are determined by its genetic makeup and by environmental influences on those genes
16
Q
Describe the conditions under which allele frequencies will not change
A
- Very large population
- Isolated from other populations
- No mutations
- Random mating
- No Natural selection
17
Q
Calculate Hardy Weinberg genotype frequencies for 2 alleles
A
p^2 + 2pq + q^2
p=(2#AA + #Aa)/2#
q=(2#aa + #Aa)/2#
18
Q
Calculate allele frequencies given genotype frequencies
A
p=(2#AA + #Aa)/2#
q=(2#aa + #Aa)/2#
19
Q
Describe the forces that can lead to evolution.
A
- genetic drift
- gene flow
- mutations
- non-random mating
- natural selection
20
Q
Effective population size
A
(Ne) is the number of individuals that would lose genetic variability at the same rate as the population with N individuals
Ne=(4Nm*Nf)/(Nm+Nf)
21
Q
Extinction vortex
A
a consequence of genetic drift and inbreeding that results in loss of genetic variability and reduced fitness until extinct
22
Q
Founder effect
A
few individuals disperse to form a new population, significant in speciation
ex: ploydactism in Amish
23
Q
Genetic Bottleneck
A
the number of individuals in a population is drastically reduced –> Likely outcome is loss of genetic diversity
24
Q
Genetic Bottleneck examples
A
The Northern Elephant Seal
20-30 individuals in 1890, >100,000 today
The California population of the Sea
Otter reduced to <100 individuals in
~1900, ~3,000 today
25
Gene flow
introduction of alleles
from other populations --> Will tend to slow down, or prevent, local adaptations
26
Genetic drift
the change in frequency of an existing gene variant in the population due to random chance
Genetic drift in small populations may lead to alleles becoming fixed or lost more rapidly
27
Inbreeding
non-random mating with close relative, lack of genetic variability means loss of fitness and higher mortality
28
Mutation
product of new alleles, genes or chromosomes. Rare, and can be harmful or neutral. Introduce genetic variability
29
Mutational meltdown
too many deleterious mutations are accumulated and become fixed, leading to extinction (ie. woolly mammoth)
30
Positive assortative mating
Reduces heterozygosity
Non random mating can change
31
Negative assortative mating
increases heterozygosity AKA dissassortative
32
Distinguish between the source of new genetic combinations and new genetic material.
Mutations in DNA producing new
alleles, genes or chromosome.
Meiosis forms gametes and sexual reproduction produces
new combinations of genes.
33
Describe examples of positive and negative assortative mating and explain the circumstances under
which such preferences might evolve
Positive Assortative Mating: small mates with small, big mates with big
Negative Assortative Mating: redheads don't fuck with redheads
34
Explain why inbreeding has negative consequences
inbreeding causes a lack of genetic diversity, more prone to inherit recessive mutations, accumulate deformities and high mortality
35
How some species are able self-
fertilize
some species with simpler genomes are able to self-fertilize because there is a lesser need for diversity
ex: bdelloid rotifers - dehydrate, intake environmental DNA fragments to repair DNA damage during rehydration
36
circumstances where genetic drift can be a significant force.
small population --> alleles fixed
- mutational meltdown - too many deletrious alleles become fixed = species decline
- genetic bottleneck
- founder effect
37
how high mutation rates in a small population might lead to mutational meltdown.
high mutation rates in small population means that the chance of reproducing with someone also affected by mutation is higher, therefore definitely giving offspring mutations. process repeats until too many deleterious mutations and population fails
38
Explain why alleles that give a fitness advantage do not always persist in small populations
positive allele variation does not always persist in small populations because small populations exagerate the fixation of alleles in a few generations, and cannot distinguish between good or bad in this process
39
Describe the consequences of genetic bottlenecks and the founder effect
genetic bottle necks and founder effect both have a population grow out of a relatively small origin, and the genes in this origin will be circulated repeatedly through generations, increasing likelihood that one organism's mutation will be present in a large amount of the population (ex. polydactyl amish)
40
Explain why the effective population can be a much smaller number than the actual population size
the effective population is a much smaller group but still representative of the actual population trends because all you need is enough to represent randomness and behavior of the genes and mating
41
Balancing selection
heterozygote advantage with frequency dependent selection
42
Continuous variation
allele frequency always changing = evolution
43
Darwinian fitness
organism ability to survive and reproduce and pass on good genes
44
Directional selection
favors one extreme (ex. oil content in corn forcible selected to be high bc agriculture)
45
Disruptive selection
favors both extremes, but only the extremes (ex. pocket mice on tan desert or dark rocky mountain. medium brown mice dont blend in therefore dead)
46
Frequency dependent selection
(positive and negative)
fitness decreases as allele frequency increases (loss of diversity)
negative frequency dependence maintains allele diversity, positive = loss
47
Genetic equilibrium
genotype frequency remains constant, no evolution
48
Heterozygote advantage
have both alleles therefore can be adaptable (favorable for offspring)
49
Stabilizing selection
favors the average (ex. infant mortality lowest at average weight)
50
Distinguish Darwinian Fitness from relative fitness
darwinian fitness is about reproduction and passing on its own genes to lead
relative fitness is the ability to survive of the given organism compared to others in the population, as well as reproductive success to pass on own genes
51
What effect does selection have on allele diversity
selection can lead to the decrease in allele diversity if an allele is strongly preferred for survival because the less advantageous ones decrease in frequency
52
Explain why rare alleles are almost always carried in a heterozygous state and, if recessive, are
therefore invisible to selection
it takes longer to irradicate a recessive allele because it does not present therefore cannot be selected against in mating
53
How is genetic variation maintained in populations
Mutation, gene flow, sexual reproduction
54
What effect does frequency dependent selection have on allele diversity? (4.2)
frequency dependent selection mean that fitness decreases as the frequency of an allele increases. therefore as frequency increases, allele diversity is less because there is more of one rather than an equal split
55
Distinguish between stabilizing, directional and disruptive selection
stabilizing = return to initial equilibrium
directional = goes constantly towards one extreme
disruptive = returns to an equilibrium that is not necessarily at the same position as the initial
56
Anisogamy
female and male gametes of unequal size (large egg, small sperm)
57
Fecundity
the ability to produce an abundance of offspring or new growth; fertility
58
Coevolution
the reciprocal
evolutionary change between
interacting species or genes
59
Fisher’s runaway hypothesis (Sexy
sons)
exaggerated traits in one sex (like ornamentation) can evolve through a self-reinforcing process where female preference for the trait and the trait itself become genetically linked
60
Fundamental asymmetry of sex
Female fitness is limited by an ability to gain the resources required to produce eggs and rear young.
61
Good genes hypothesis
females select mates based on traits that indicate the male's ability to pass on genes that will increase the survival and reproductive success of their offspring
62
Isogamy
Having gametes of equal size
63
Intrasexual selection
intrasexual selection, or competition between members of the same sex (usually males) for access to mates
64
Intersexual selection
intersexual selection, where members of one sex (usually females) choose members of the opposite sex.
65
Müllers ratchet
deleterious alleles accumulate due to lack of recombination cleared by sexual reproduction
66
Red Queen hypothesis
An evolutionary theory that explains how species must constantly adapt and evolve to survive because their environment- and the organisms they interact with- are also evolving. *DOES NOT BETTER CHANCE OF SURVIVAL FOR THE SPECIES*
67
Sensory exploitation hypothesis
male mating traits evolve to exploit pre-existing sensory biases or preferences in females, rather than being directly selected for their survival value
68
sexual selection
Process by which individuals with certain inherited characteristics are more likely than other individuals of the same sex to obtain mates
69
Sexual dimorphism
Refers to the difference in size, shape, color, or other physical traits between males and females of the same species. These differences are driven by natural selection and sexual selection.
70
sperm competition
when multiple males' sperm compete to fertilize a female's eggs, males evolve traits and behaviors to increase their chances of fertilization, leading to post-copulatory sexual selection
71
Describe the principle advantages and disadvantages of sexual reproduction
Advantages:
1. combining beneficial mutations
2. faster evolution
3. clearing of deleterious alleles
Disadvantages:
1. two fold cost of sex
2. reduced relatedness
3. search cost
4. STDs
72
Describe the fundamental asymmetry of sex and explain why males are often larger and more
brightly colored and females are often highly selective in their mate choice
Female fitness is limited by an ability to gain the resources required to produce eggs and rear young.
Females are highly selective because because they want to produce the most viable offspring with a father that has good genes.
Male fitness is limited
by the ability to attract
mates.
Larger and brightly colors mates attracts females as having strong, good genes, enticing them to reproduce.
73
Explain how sexual selection can lead to situations where males have traits that reduce their
survivorship
Fitness is a function of BOTH
survival and fecundity.
Although a trait may actually be a disadvantage for survival, it promotes selection of a mate against other competition, increasing the number of offspring with the trait.
74
Give examples of coevolution and explain how the red queen hypothesis applies
selection for a faster lynx = selection for a faster hare
selection for moths with long tongues = selection for flowers with long corolla
Red Queen Hypothesis: species are constantly forced to evolve due to other evolving species and changes in environment - ADAPTATION NEVER STOPS
75
Distinguish between ‘Good Genes’, “Sexy Sons’ and ‘Sensory exploitation’ as theories for female
mate choice
Good Gene Theory: females select mates that exhibit traits that indicate the male has genes that will favor survival and success of offspring
Sexy Son's Theory: females select mates with ornamental and attractive traits that when passed down to their offspring will also allow them to have reproductive success
76
Allopatric speciation
Occurs when a physical barrier separates a population, preventing them from interbreeding. Over time, genetic differences accumulate, leading to a new species. (Ex: a group of squirrels are split by a river, and after many generations, they become two distinct species.)
77
Auto and Allopolyploidy
Autopolyploidy- multiple chromosome sets derived from one speciesAKA new species from weird genetics of previous species
Allopolyploidy- multiple chromosome sets derived from more than one species. AKA new species from hybridization
*Both of these require errors. (Ex: chromosome duplication in mitosis)
78
Biological species concept
Actually or potentially interbreeding populations which are reproductively isolated from other such groups.
*Works well for extant sexually reproducing species.
79
Fusion
When hybrids are as fit as parents.
80
Hybrid zone
When two diverged species could possibly interact/mate.
81
Genetic divergence
Refers to the process where two or more populations of the same species accumulate genetic differences over time, leading to reduced interbreeding and possibly the formation of a new species
82
Hybridization
The interbreeding of individuals from two different species or distinct populations, resulting in offspring (hybrids) that are a genetic mix of both parent species.
83
Morphological species concept
Defines a species based on physical traits like shape, size, and structure.
Key idea: Even if two organisms look similar, they could be considered the same species. Even if they look different, they are separate species.
84
Parapatric speciation
Happens when populations live in different environments but share a small contact zone where some interbreeding happens. Natural selection favors traits suited for each environment, leading to divergence. (Ex: plants growing in polluted soil evolve differently from those in clean soil.)
85
Peripheral isolate model (peripatric speciation)
A type of allopatric speciation where a small population breaks off from a larger one and evolves into a new species. This is usually due to them being in a new environment and having a small gene pool.
86
Postzygotic isolation
Refers to reproductive barriers that occur after fertilization, preventing an offspring from developing into fertile adults.
87
Prezygotic isolation
The separation of different species to keep them from creating offspring by preventing the gametes from forming a zygote.
88
Reinforcement
When hybrids are less fit.
89
Reproductive isolation
Mechanisms, behaviors, and physiological processes that prevent different species from successfully interbreeding and producing fertile offspring, thus maintaining distinct genetic pools and driving speciation.
90
Distinguish between allopatric, parapatric and peripatric models of speciation
Allopatric= Geographic separation
Parapatric= Some contact, but different environments
Peripatric= Small group separated from original species to evolve into a new one
91
Speciation
The evolutionary process where a single ancestral species diverges into two organisms more distinct species, driven by factors like geographic isolation, genetic changes, and reproductive isolation.
92
Sympatric speciation
Occurs without physical separation- new species evolve while living in the same area. This usually happens due to behavioral, ecological, or genetic changes. (Ex: some fruit flies like to lay eggs in mangoes while others like to lay eggs on bananas, leading to reproductive isolation from original group)
93
Describe three different, and widely used, species definitions and the species they are used for
Biological species concept: Actually or
potentially interbreeding populations
which are reproductively isolated from other such groups
(used for current sexually reproducing species)
Phylogenetic species concept: Clusters of organisms with a shared, unique evolutionary history, based on genetic data and phylogenetic analysis, forming a distinct branch on the tree of life.
(used for microbes)
Morphological species concept: Species based on distinct morphological (physical) features, grouping organisms that look similar
(used for fossils)
94
Explain how speciation can occur when two populations that exist in the same location (Sympatric
speciation
Sympatric speciation: no physical barriers but reproductive isolation
1. polyploidy - occurs due to errors in duplication of chromosomes and reduction of gametes
2. habitat isolation - prefer to live in certain areas
95
What are the possible outcomes for a hybrid zone over time?
Hybrid less fit: Reinforcement AKA strong reproductive barriers
Fusion AKA species merge into one
Hybrid more fit: Stability AKA hybrid zone persists
96
Describe different isolating mechanisms that can keep species apart distinguishing between
prezygotic and postzygotic barriers.
Pre-zygotic barriers: prevents mating or fertilization between different species
Post-zygotic barriers: prevents hybrid offspring from surviving or reproducing
97
adaptive radiation
Evolution of major novel traits:
speciation from a common ancestor in order to adapt to different ecological niches
98
Alpha (origination rate)
number of new species/originations
99
Dispersal
ability of organism to move and colonize new areas
100
Background extinction
opposite of sudden mass extinction, very slow and gradual extinction due to environmental factors
101
Gradualism
change occurs little by little, accumulated over time
102
Macroevolution
Evolution above the species level caused by patterns of speciation and extinction
103
Omega (extinction rate)
number of species lost/extinct
104
Mass extinction
a sudden catastrophic event or natural disaster causes the rapid extinction of a species
105
Punctuated equilibria
evolutionary change is due to isolated, rapid periods of speciation
106
Standing Diversity
genetic variation present in a population at any given time
107
Explain how this may affect our interpretation of the fossil record
fossil record is very biased on what, where and how fossils are preserved, limiting how we judge evolution
108
Turnover
alpha + omega:
replacement of a species over time
(new species) + (extinct species)
109
Describe some of the ways the fossil record is biased
Preservation collected only at rare intervals if certain conditions are met
Biased on what and where fossils are preserved, and how we are able to find them
110
Explain what the macroevolutionary red queen says about species improvement over time
Species have a constant rate/probability of extinction over time. The same in population the species is, the closer it is to extinction (duh)
111
Vicariance
processes that can create barriers that impact evolution ie mountain range formations, sea levels rising, continental drift
112
Calculate standing diversity and turnover across geologic time
Turnover = the new species (alpha) + the extinct species (omega) per stage
Standing Diversity = (sum of alpha up until now) - (sum of omega up until now)
113
Compare and contrast macroevolution and microevolution
Macroevolution:
mutations, gene flow, genetic drift and natural selection over time, causing speciation or evolutionary change (phylogeny)
*not directly observable
*experiments impossible
Microevolution: how changes of an individual influences the bigger picture of a population and even species (genetics)
* directly observable
*experiments possible
114
Describe some of the circumstances where we see high levels of origination of species
Origination of species is high when:
1. Vacant niches are available after mass extinctions or in new environments
2. Evolution of major novel traits
(adaptive radiation)
3. Evolution of new mutualisms
115
Describe different types of fossils and the information they can give us
Intact = DNA information
Trace = Ecology patterns
Casts = morphology
116
Give two evolutionary explanations for high tropical diversity
1. Nursery hypothesis (high alpha) - abnormally high recruitment of adult species and populations
2. Museum Hypothesis (low omega) - older less adaptable species are preserved due to stable environemnt
117
Compare and contrast background extinction and mass extinctions
Background extinction:
happens gradually over time due to persistent environmental factors, weening off
Mass extinction: catastrophic event that occurs suddenly, forces rapid extinction and killing of a species
118
Contrast gradualism with the punctuated equilibrium model
Gradualism: changes in evolution occurs constant and slowly over time
Punctuated Equilibrium: evolutionary change occurs in isolated periods and occurs very rapidly
119
Analogous and homologous traits
analogous: not derived from common ancestor, due to convergent evolution (ex. shark fin ~ penguin wing ~ dolphin mammal)
Homologous: derived from common ancestor (ex. human arm = cat leg = whale flipper = bat wing)
120
Clade
Consists of an ancestor species and all of its descendants.
121
Consensus tree
tree with branches that are undistinguished in length/relation because a definitive relation cannot be determined
122
Monophyletic
similar due to recent relation (mammals, birds, insects)
123
Convergent evolution
traits are evolved separately by different species, but present the same due to similar environmental need for them (ex. shark fin ~ penguin wing ~ dolphin mammal)
124
Outgroup
group with the most distant relation, not being considered
125
Paraphyletic
many divergences, some descendants do not fit into group (birds in reptile family)
126
Node
hypothetical common ancestor
127
Polyphyletic
similar due to environment, not ancestry (algae, marine mammals)
128
Phylogeny
aka phylogenic tree
129
Plesiomorphy (shared ancestral
character)
shared ancestral character
130
Parsimony (Occam’s razor)
do not make more assumptions than you have to, and choose the tree that assumes the least number of evolutionary changes because it is more likely to have occurred that way
131
Polytomy
consensus tree where computer program cannot pinpoint relations, agreement and disagreement in branches
132
Root
single origin of whole tree, time always starts here and runs into the tree
133
Sister taxa
two groups that share the same node
134
Synapomorphy (shared derived
character)
trait that helps determine organization of tree because more than one have it but not all (ex. placenta babies differentiates horses and bats from kangaroos)
135
Taxon (Taxa)
a group of organisms represented by the end of a line of the tree
136
Interpret phylogenetic trees presented in different ways
NA
137
Identify monophyletic and non-monophyletic groups
monophyletic groups all fit into the description, and are smaller groups because larger groups include more variance. non-monophyletic groups are often larger, either not sharing a recent relative (polyphyletic) or groups with such differentiated individual they do not resemble the rest of the group (birds make reptiles non-monophyletic)
138
Explain how scientists distinguish homology from analogy
Homology is told apart from analogy because homology will have very specific replicated bone structure that can be identified. Analogy developed separately therefore will have less specific structural similarity
139
Explain how shared derived characters can be used to construct phylogenetic trees
shared derived characteristics tell you where to have a node because the groups began to deviate. (ex. kangaroos, horses, and bats all have hair, but only horses and bats have placental offspring, and only bats can fly. therefore kangaroos split off from horses and bats, and then horses and bats split from each other)
140
Explain how parsimony can be used to distinguish between multiple possible phylogenetic trees
parsimony can be used to distinguish between multiple possibly phylogenetic trees because it means you have to be as specific as possible, creating the tree requiring the fewest evolutionary changes that explains the data
141
TT = 0.56
Tt = 0.28
tt = 0.16
Is this population in Hardy-Weinberg equilibrium?
No; there are more homozygotes than expected.
142
Which of the following would be least likely to appear in the fossil record?
desert-dwelling species
143
Which of these is a POSTZYGOTIC reproductive isolation mechanism that could lead to the
speciation of the two subpopulations?
Decreased fitness of hybrids
144
There is a population of fish that has a range of different sized male individuals. Large males are
best at defending territories and thus get more chances to mate with females. Small males are too
small to defend a territory and get no mating opportunities but medium sized males sometimes
obtain territories and matings. This is an example of what type of selection?
Directional selection
145
According to the phylogenetic tree in the figure above, the G. intestinalis group, and its common
ancestors, constitutes a ________ group (image shows group leaving out one group on end of clade)
paraphyletic
146
By examining the phylogenetic tree diagrammed in the figure above, what conclusion can you
draw about the species G. microti?
It is part of a monophyletic group that also includes G. intestinalis
147
The golden hamster (a rodent often used in biomedical research or owned as a pet) is believed to
have arisen as a separate species following a mating between a male and a female of two different
hamster species. Which of the following mechanisms might explain this speciation event?
allopolyploidy
148
Which of the following pairs (person and concept) is INCORRECT?
Wallace - inheritance of acquired characteristics
149
Starlink corn is a variety that is fixed for an allele that codes for the production of a protein that is
effective at killing caterpillars if they attempt to eat the plant. Which of the following statements
is TRUE?
I. Gene flow can spread this allele to species that are reproductively isolated from corn.
II. Gene flow can spread this allele to other populations of corn.
III. Genetic drift will introduce new alleles at this locus
II only
150
The cladogram below suggests that
the traits of feathers and hollow bones were later used during flight in taxa D, but may
have had different functions in earlier species
151
Which is the BEST definition of microevolution?
A change in the gene pool of a population over a succession of generations.
152
Put the following events that occur during the process of natural selection in the correct order so
that the first leads to the second leads to the third etc.
I Differential reproductive success occurs
II Allele frequencies change
III Environmental change occurs
III then I then II
153
Prior to the early 1800’s and the work of Lyell and Darwin, the prevailing belief was that Earth
is:
a few thousand years old, and species are unchanging
154
Claytonia virginica is a woodland spring herb with flowers that vary from white, to pale pink, to
bright pink. Slugs prefer to eat pink-flowering over white-flowering plants (due to chemical
differences between the two), and plants experiencing severe herbivory are more likely to die.
The bees that pollinate this plant also prefer pink to white flowers, so that Claytonia with pink
flowers have greater relative fruit set than Claytonia with white flowers. A researcher observes
that the percentage of different flower colors remains stable in the study population from year to
year. Given no other information, if the researcher removes all slugs from the study population,
what do you expect to happen to the distribution of flower colors in the population over time?
The percentage of pink flowers should increase over time.
155
156
To apply the principle of maximum parsimony to the construction of a phylogenetic tree,
________.
choose the tree that represents the fewest evolutionary changes, either in DNA sequences
or morphology
157
Currently, two of the living elephant species (X and Y) are placed in the genus Loxodonta, and a
third surviving species (Z) is placed in the genus Elephas. Assuming this classification reflects
evolutionary relatedness, which of the following is the most accurate phylogenetic tree?
X and Y are sisters
(X and Y) are sister with Z
158
Laboratory evidence indicates that bacteria that express genes that make them resistant to
antibiotics have lower fitness when the antibiotic is not present in the environment. Based on this
fact, you would expect the rate of occurrence of antibiotics-resistant bacteria to be lowest in
countries where:
antibiotics are never used
159
Genetic variation ________
must be present in a population before natural selection can act upon the population
160
Suppose 64% of a remote mountain village can taste phenylthiocarbamide (PTC) and must,
therefore, have at least one copy of the dominant PTC taster allele. If this population conforms to
Hardy-Weinberg equilibrium for this gene, what percentage of the population must be
heterozygous for this trait?
48%
161
Genetic diversity is estimated to be about 2.5 times larger in chimpanzees than humans. An
explanation that MIGHT be responsible for this difference is that:
humans probably went through a genetic bottleneck in population size
162
The horizontal axis of the cladogram depicted below is a timeline that extends from 100,000
years ago to the present; the vertical axis represents nothing in particular. The labeled branch
points on the tree (V-Z) represent various common ancestors. Let's say that only since 50,000
years ago has there been enough variation between the lineages depicted here to separate them
into distinct species, and only the tips of the lineages on this tree represent distinct species.
Which of the five common ancestors, labeled V-Z, is the common ancestor of the greatest number
of species, both living and extinct?
Y
163
Cystic fibrosis is a rare recessive genetic condition. Suppose that the allele that causes Cystic
fibrosis has a frequency of 0.001 in a certain population. If the population can be assumed to be at
Hardy Weinberg equilibrium approximately how many heterozygous carriers of the disease will
be born for every individual born with the disease?
1998
164
An earthquake decimates a ground-squirrel population, killing 98% of the squirrels. The
surviving population happens to have broader stripes, on average, than the initial population. If
broadness of stripes is genetically determined, what effect has the ground-squirrel population
experienced during the earthquake?
a genetic bottleneck
165
The position of species B in the diagram below indicates that species B:
lacks synapomorphies shared by C, D, and E
166
A large population of laboratory animals has been allowed to breed randomly for a number of
generations. After several generations, 25% of the animals display a recessive trait (aa), the same
percentage as at the beginning of the breeding program. The rest of the animals show the
dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants.
What is the most reasonable conclusion that can be drawn from the fact that the frequency of the
recessive trait (aa) has not changed over time?
The two phenotypes are about equally adaptive under laboratory conditions
167
In 1983, a population of dark-eyed junco birds became established on the campus of the
University of California, San Diego (UCSD), which is located many miles from the junco's
normal habitat in the mixed-coniferous temperate forests in the mountains. Juncos have white
outer tail feathers that the males display during aggressive interactions and during courtship
displays. Males with more white in their tail are more likely to win aggressive interactions, and
females prefer to mate with males with more white in their tails. Females have less white in their
tails than do males, and display it less often. (Pamela J. Yeh. 2004. Rapid evolution of a sexually
selected trait following population establishment in a novel habitat.
The UCSD campus male junco population tails were, on average, 36% white, whereas the tails of
males from nearby mountain populations averaged 40-45% white. If this observed trait difference
were due to a difference in the original colonizing population, it would most likely be due to
________
a founder effect
168
Which of these three cladograms are equivalent (just drawn differently)?
B and C
169
Which of the following is the most predictable outcome of increased gene flow between two
populations?
decreased genetic difference between the two populations
170
The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages,
whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not
vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation
selects for bacteriophages whose genomes are also methylated. As new strains of resistant
bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not
methylated and whose restriction enzymes instead degrade methylated DNA. The outcome of the
conflict between bacteria and bacteriophages at any point in time results from ________
frequency-dependent selection
171
You are confronted with a box of preserved grasshoppers of various species that are new to
science and have not been described. Your assignment is to separate them into species. There is
no accompanying information as to where or when they were collected. Which species concept
will you have to use?
morphological
172
You want to study divergence of populations, and you need to maximize the rate of divergence to
see results within the period of your grant funding. You will form a new population by taking
some individuals from a source population and isolating them so the two populations cannot
interbreed. What combination of characteristics would maximize your chance of seeing
divergence in this study?
1. Choose a random sample of individuals to form the new population.
2. Choose individuals from one extreme to form the new population.
3. Choose a species to study that produces many offspring.
4. Choose a species to study that produces a few, large offspring.
5. Place the new population in the same type of environment as the source population.
6. Place the new population in a novel environment compared to that of the source
population
2, 3, and 6
173
In the oceans on either side of the Isthmus of Panama are 30 species of snapping shrimp; some
are shallow-water species, others are adapted to deep water. There are 15 species on the Pacific
side and 15 different species on the Atlantic side. The Isthmus of Panama started rising about 10
million years ago. The oceans were completely separated by the isthmus about 3 million years
ago.
In the figure, the isthmus separates the Pacific Ocean on the left (side A) from the Atlantic Ocean
on the right (side B). The seawater on either side of the isthmus is separated into five depth
habitats (1-5), with 1 being the shallowest.
Which habitats should harbor snapping shrimp species with the greatest degree of genetic
divergence from each other?
A5 and B5
174
Beetle pollinators of a particular plant are attracted to its flowers' bright orange color. The beetles
not only pollinate the flowers, but they mate while inside of the flowers. A mutant version of the
plant with red flowers becomes more common with the passage of time. A particular variant of
the beetle prefers the red flowers to the orange flowers. Over time, these two beetle variants
diverge from each other to such an extent that interbreeding is no longer possible. What kind of
speciation has occurred in this example, and what has driven it?
sympatric speciation; habitat differentiation
175
The phenomenon of fusion is likely to occur when, after a period of geographic isolation, two
populations meet again and ________
an increasing number of viable, fertile hybrids is produced over the course of the next
100 generations
176
Based on the tree below, which statement is not correct?
Lizards are more closely related to salamanders than to humans
177
For which one of the following observations were both Lamarck's hypothesis and Darwin's
hypothesis in complete agreement?
Gradual evolutionary change explains why organisms are well-suited to their environments
178
The typical tempo of extinctions within a particular taxon is called:
Background extinction
179
Which of the following trees, if any, depicts the same relationship among species as shown
above?
a
180
The punctuated equilibria model of evolutionary change proposes that most morphological
change occurs:
rapidly, during the speciation process
181
Which statement BEST summarizes the process of evolution by natural selection:
Those genotypes that code for phenotypes that transport more genome copies from
generation to generation will eventually predominate within a population.
182
Use the information below for the next two questions. Suppose that a new mutation occurs in a population
of flightless birds on an oceanic island. The mutation produces bright red coloration of the beaks of males
(instead of the normal black beak coloration). The island population is divided into two subpopulations
(east and west) by a steep ocean-filled canyon that the birds cannot cross. The west side of the island has
a population of snakes that hunt the birds, but the east side of the island has no major predators. Males
expressing the mutation have a 20% increase in mating success due to female preference. When snakes
are present the survival of birds with bright red beaks is reduced by 30% compared to that of that of
black-beaked males. The mutation does not harm or help males in any other way.
On the east side of the island, the mutation would be expected to
Increase due to the operation of intersexual selection
183
On the west side of the island, the mutation would be expected to:
Decrease in frequency due to decreased Darwinian fitness
184
What is the turnover rate in stage B in the figure below?
16 (6 extinctions plus 10 originations)
185
Use the following information for the next two questions. In a hypothetical population of humans a
mutation is found (the H allele) that makes people unusually amorous. People expressing the gene tend to
have larger families, but are unusual in no other way. You can assume mortality is small enough to
ignore. The Census bureau collects the following data from a random sample of the population.
HH = 40 # of children 5
Hh = 20 # of children 2.5
hh = 440 # of children 2
Total 500
The frequency of the H allele in this sample is:
0.1
186
The relative fitness of the Hh genotype is:
0.5
187
Upon being formed, oceanic islands, such as the Hawaiian Islands, should feature what
characteristic, leading to which phenomenon?
a variety of empty ecological niches, leading to adaptive radiation
188
Consider an experiment in which a large population of bacteria was stored in a freezer (which
does not harm the bacteria). On the first day of the experiment a sample of the bacteria was taken
from the freezer, thawed, and infected with a virus. On the next day the progeny from the virus
was collected and used to infect a new sample of bacteria from the freezer. This procedure was
continued each day for 2 weeks. The virus rarely kills the bacteria but it does slow reproduction
of the bacteria by causing it to make virus progeny in addition to carrying out its own
reproduction. Virus that reduce the fitness of the bacteria more have higher fitness because they
produce more offspring. The level of harm (fitness reduction) caused by the virus to the bacteria:
Is expected to increase over the course of the experiment
189
Use the following information for the next two questions. Consider a species of finch (a bird) that has
been extensively studied in the wild in Australia and also in large enclosures in the USA and Europe.
Males have bright red bills and red patches of feathers and the females have duller bills and lack red
feather patches. When red bracelets were placed on the legs of males, this treatment increased the male’s
ability to attract mates and repel male rivals. When artificial white feather plumes were attached to the
heads of males (these head plumes were not found in nature on these birds) they also made the males
more attractive to females but did not affect their ability to repel male rivals. However, these plumed
males spent more time trying to attract additional mates and helped their existing mate far less with
feeding their young (compared to males without plumes).
The information about the coloration of males’ feathers and beak (and the effect of colored
bracelets) supports which form of sexual selection
both intersexual and intrasexual
190
If males in Western Australia had duller feathers than males in Eastern Australia and female
choice for bright males was equally strong in both regions, then which is the best hypothesis to
explain this difference:
Predation was probably weaker in Eastern Australia
191
With its dazzling plumage, the snow goose is aptly named and is one of the easiest geese to
identify. However there are two types of snow goose, one of which is actually a dark, gray-
colored bird known as the blue goose. Although the white and blue forms occasionally interbreed
the white individuals mate with other white individuals far more frequently than expected by
chance. This is an example of:
non-random mating
192
wallace
species evolve through the survival and reproduction of individuals with advantageous traits, passing those traits to offspring
193
hutton
geological formation may be explained by gradual processes
