EVOLUTION Flashcards
1
Q
Definition:
Evolution
A
Change through time
2
Q
Definition:
Biological/Organic Evolution
A
change in heritable characteristics in populations over time
3
Q
Definition:
Theory
A
A well-established, well-supported, well documented explanation for our observations and is supported by facts
4
Q
Short Answer:
Is a 1% difference at the genetic level between two organisms enough to differentiate them?
A
Yes, humans and chimpanzees are 99% identical but are significantly different.
5
Q
Short Answer:
What concepts are part of the Special Creation theory?
A
- Species are independent (unrelated)
- Life on Earth is young (~6000 years old)
- Species are immutable (incapable of change)
6
Q
Short Answer:
What concepts make up Typological Thinking?
A
- Every organism is an example of a type (perfect essence)
- Types were unchanging: fish, human, plant, worm, carnivore
7
Q
Short Answer:
What are the concepts that mke up the Scale of Nature (Great Chain of Being)?
A
- Ordered species based on increasing size and complexity: rock & plants at the bottom, humans at the top
- Species were fixed types
8
Q
Short Answer:
What concepts were part of Lamark’s Species Change Through Time?
A
- Life is driven from simple to complex
- Complex species descended from microbes
- Microbes continually generated spontaneously
- Organisms evolve by moving up the chain over time
- Produces larger and more complex species over time
- Adaptation occurs through inheritance of acquired changes
9
Q
Definition:
Acquired characteristics
A
Characteristics one is not born with, but acquired throughout one’s life time
10
Q
Short Answer:
Why are acquired characteristics not passed on to offspring?
A
They are a result of environmental influence, and not part one’s genome.
11
Q
Short answer:
What are the concepts that make up Natural Selection?
A
- Change does not follow linear progression
- Based on variation amongst individuals in populations
- Individuals with certain traits produce more offspring than others without these traits
- Individuals are under natural selection, but populations evolve
- Population thinking
12
Q
Short Answer:
What concepts were covered in Darwin’s Origin of Species?
A
- Species change through time
- Species are related by common ancestry (leads to descent with modification)
13
Q
Short Answer:
Examples of evidence of Change Through Time?
A
- Fossils record
- Vastness of geologic time
- Evidence of extinction
- Transitional forms
- Vestigial traits
14
Q
Example:
What is an example of a transitional form?
A
Birds share a common ancestor with reptiles, an fossil that is not quite bird nor quite reptile should be discovered (archeopteryx)
15
Q
Definition:
Vestigial traits (dead genes)
A
Remnants of something that used to serve a purpose in the past (ex: tail bone)
16
Q
Short answer:
What is evidence of descent from a common ancestor?
A
- Similar species are found in the same geographical area
- Homology
- New species are generated from preexisting species (ex: polar bears are descendants of brown bears)
17
Q
Short answer:
Name/describe the types of homology
A
- Structural: bones are the same, but develop in different ways
- Genetic: similar DNA, RNA, or amino acid sequences due to inheritance from common ancestor
- Development: development is similar between organisms
18
Q
Short answer:
Why is it difficult to see evolution occurring?
A
It takes time to see it; small changes over millions of years lead to big changes
19
Q
Short ANswer:
Why did Darwin argue that evidence of extinction supports the theory of evolution?
A
It shows that the number and types of species have changed over time.
20
Q
Short Answer:
Researchers have found fossils of Eocene horse species in Colorado. Deeper deposits contain smaller species, and more recent deposits contain larger species. How does this observation support the theory of evolution?
A
It provides evidence that species change over time.
21
Q
Definition:
Selective breeding
A
choosing parents with particular characteristics to breed together and produce offspring with more desirable characteristics
22
Q
Short Answer:
What are Darwin’s Postulates?
A
- Individuals within species are variable (ex: human height)
- Some of these variations are passed to offspring
- In every generation, more offspring are produced than can survive (ex: large litters, one surviving offspring)
- The survival and reproduction of individuals are not random
23
Q
Case Study:
What was revealed through the study of medium ground finches vs large ground finches?
A
- Individual do not change when they are selected, the simply produce more surviving offspring than other individuals do
- During the drought, individual beaks did not change; beak depth increased over time, deep-beaked individuals had greeted reproductive success
- Adaptation occurs when the allele frequencies in a population change in response to natural selection
24
Q
Short Answer:
What is wrong with the phrase “Evolutionary change occurs in individuals”?
A
- Natural selection just sorts existing variants among individuals; it doesn’t change them
- Evolutionary change occur only on populations
- Acclimatisation is not adaptation (must have alleles that code for characteristic)
25
# Short Answer:
What is wrong with this sentence: “Evolution is goal directed”
* Adaptations do not occur because organisms want or need them
* Mutation, the source of new alleles, occurs by chance and in random directions
* Loss of traits can be adaptive
* These is no such thing as a higher or lower organism
26
# Short Answer:
What is wrong with this phrase: “Evolution perfects organisms”
* Not all traits are adaptive
* Some traits cannot be optimised due to fitness trade-offs
* Some traits are limited by genetic, historical, or environmental constraints
* Natural selection does not create new traits
* Selects for traits already present in populations
* Current, local environment determines which traits selected for or selected against in a population
27
# Short Answer:
Why might organisms that have been artificially selected be less fit?
Artificially selected organisms may be less fit in natural settings due to reduced genetic diversity, narrow trait emphasis, potential trade-offs, and the loss of essential behavioral adaptations and natural instincts. Artificial selection prioritizes specific objectives and environments, making these organisms less adaptable to natural or unpredictable conditions
28
# Defintition:
Fitness
a measure of the extent to which an individual’s genotype is represented in the next generation
29
# Definition
Adaptation
a trait that enhances the fitness of an organism to its environment
30
# Definition
Decsent with Modification
suggests that over time, species change as they pass their traits to their descendants. This change occurs through the accumulation of genetic variations, mutations, and adaptations
31
# Long Answer:
Assess whether Darwin’s four postulates are true in any given example, explain why evolution must occur if all four are true.
* Over generations, individuals with advantageous traits will become more common in the population because these traits are passed on to their offspring.
* The frequency of advantageous traits increases, while the frequency of less advantageous or detrimental traits decreases.
* This process results in a change in the genetic makeup of the population over time, which is the essence of evolution.
* Over long periods, this gradual accumulation of beneficial traits can lead to the emergence of new species, as populations become increasingly distinct from their ancestors.
32
# Long Answer:
Assess whether Darwin’s four postulates are true in any given example, explain whether evolution will occur if any of the four are not true.
* Variation Not Present: If there is no variation in traits within a population, there is no raw material for natural selection to act upon. In such cases, evolution as driven by natural selection cannot occur.
* Heritability Absent: If traits are not heritable, then even if there is variation, advantageous traits cannot be passed on to the next generation. Without heritability, evolution cannot proceed through the mechanism of natural selection.
* No Struggle for Existence: If there is no competition for resources or if all individuals can survive and reproduce equally, then there is no selective pressure. Natural selection relies on the differential survival and reproduction of individuals based on their traits. Without a struggle for existence, evolution through natural selection is unlikely.
* Differential Survival and Reproduction Not Occurring: If individuals with advantageous traits do not have a higher chance of surviving and reproducing, then there is no mechanism driving the accumulation of these traits in the population. Evolution relies on differential fitness based on traits.
33
# Short Answer:
Explain what fitness means in this context: Long petals increase the fitness of certain flowers
by increasing their ability to attract pollinator
"Fitness" refers to the evolutionary advantage of certain flowers with long petals. When flowers have long petals, it increases their fitness by enhancing their ability to attract pollinators such as bees, butterflies, or hummingbirds. This higher fitness means these flowers are more likely to successfully reproduce and pass on their genes, leading to a greater representation of long-petaled traits in future generations
34
# Short Answer:
Explain why individuals do not change when natural selection occurs
Individuals do not change during natural selection because natural selection operates on the variation already present in a population over generations, favouring those with advantageous traits, but it does not directly modify individual organisms within their lifetimes
35
# Short Answer:
Explain why trade-offs and genetic and historical constraints prevent adaptations from being perfect:
* Resource Allocation Trade-offs: Organisms have finite resources, and enhancing one trait often comes at the cost of another. For example, a predator might prioritize speed but compromise on stealth, impacting the perfection of both traits.
* Genetic Constraints: Genetic variation within populations is limited, and not all mutations result in beneficial adaptations. Evolution works with existing genetic diversity, which can constrain the pursuit of perfection.
* Historical Legacies: Adaptations build upon ancestral traits. Traits that were once advantageous may persist, even if they are not optimal for current conditions. This historical baggage limits the perfection of adaptations
36
# Short Answer:
Factor that affect phenotype:
Genotype and Environment
37
# Definition:
Genotype
set of alleles possessed by the individual
38
# Definition:
Species
A group of individuals that can exchange genetic material through interbreeding to produce fertile offspring
39
# Definition:
Gene pool
All the alleles present in all individuals in a population or species
40
# Definition:
Population genetics:
he study of processes that change the allele and genotype frequencies in populations
41
# Definiton:
Populations:
interbreeding groups of organisms of the same species living in the same geographical area that produce fertile offspring
42
# Short answer:
What are the sources of genetic variation?
Mutation & Recombination
43
# Definition:
Somatic mutations
mutation that occur in somatic cells (ex: skin cancer)
44
# Definition:
Germ-line mutations:
a mutation that occur in eggs and sperm or in the cells that give rise to these reproductive cells and therefore is passed on to the next generation
45
# Short answer:
What type of effect do mutations have?
Neutral, deleterious, or advantageuos/beneficial
46
# Short answer:
Why are germ-line mutations more important in evolution than somatic ones?
Germ-line mutations are passed on to the next generation, but somatic mutations are not. Evolution is the change in the genetic makeup of populations from generation to generation, so germ-line mutations are key to this process.
47
# Definition:
Allele frequency
the proportion of a specified allele among all the alleles of a gene in a population
48
# Definition:
Fixation
the process by which one allele replaces all of the other alleles in a population
49
# Definition:
Genotype frequency:
the proportion of a specified genotype among all the genotypes for a particular gene or set of genes in a population
50
# Solve:
In a survey of DNA sequences from a population of 500 mice, we find one polymorphic nucleotide position, which is either G or T. We find 800 G’s in our sample. What is the frequency of the T allele?
With 500 individuals, we have a total of 500 x 2 = 1000 sequences. 800 are G, so 1000-800 = 200 are T. The frequency of the T allele is 200/1000 =0.2
51
# Definition:
Hardy-Weinberg equilibrium
a state in which allele and genotype frequencies do not change over time, implying the absence of evolutionary forces. It also specifies a mathematical relationship between allele frequencies and genotype frequencies
52
# Short Answer:
What are the conditions/assumptions of the Hardy-Weinberg equilibrium?
* There is no difference in the survival and reproductive success of individual with different genotypes, no natural selection
* The population is sufficiently large to prevent sampling errors from genetic drift
* Populatins are not added to or subtracted from by migration, no gene flow
* There is no mutation
* Individuals mate at random
* No overlapping generations
* Organisms are diploid
53
# Definition:
Selection
the retention or elimination of mutations in a population of organisms
54
# Defintion:
Genetic Drift
a random change in the frequency of an allele due to the statistical effects of finite population size
55
# Definiton:
Nonrandom mating:
mate selection biassed by genotype or relatedness
56
# Short answer:
What can and can’t we conclude about a population whose allele frequencies are not in Hardy-Weinberg equilibrium?
We can conclude that the population is evolving, but we cannot tell which mechanism– selections, genetic drift, migration, or mutation– is causing it to evolve
57
# Short answer:
Types of natural selection
Postivie, negative, balancing, and sexual selection
58
# Definition:
Positive selection
natural selection that increases the frequency of a favourable allele
59
# Definiton:
Negative selection
natural selection that reduces the frequency of a deleterious allele
60
# Definiton:
Balancing selection:
natural selection that acts to maintain two or more alleles of a given gene in a population (ex: heterzygote advantage)
61
# Short Answer:
Types of selection distributions:
Stabilising, directional, disruptive, balancing
62
# Definition:
Stabilising selection:
a form of selection that selects against extremes and therefore maintains the status quo
63
# Definition:
Directional selection
a form of selection that results in a shift of the mean value of a trait in a population over time
64
# Definition:
Disruptive selection
a form of selection that operates in favour of extremes and against intermediate forms, selecting against the mean
65
# Definiton:
Selective pressure
a full set of environmental conditions, both abiotic and biotic, that influences the evolution of a population by natural selection
66
# Definition:
Sexual selection
a form of selection that promotes traits that increase an individual's access to reproductive opportunities
67
# Short answer:
What are the types of sexual selection?
Intrasexual selection and intersexual selection
68
# Definition:
Intresexual selection
* a form of sexual selection involving interactions between individuals of one sex
* uses armaments (antlers)
69
# Definition:
Intersexual selection
* a from of sexual selection involving interaction between males and female
* uses ornaments
70
# Short answer:
Why does negative selection not succeed in eliminating deleterious recessive alleles from a population?
In the situation, we assume heterozygotes are not harmful, so negative selection can only ensure that the deleterious allele nevers becomes high in frequency
71
# Short answer:
Why is natural selection not truly analogous to artificial selection?
There is no selector/breeded/farmer involved. Artificial selection is driven by a specific goal, but natural selection is driven by competition for resources
72
# Short answer:
Sexual selection tends to cause bigger size, more elaborate weaponry, or brighter colours in males. Is this an example of stabilising, directional, or disruptive selection?
It is an example of directional selection.
73
# Definiton:
Bottleneck
an extreme, usually temporary, reduction in population size that may result in marked loss of genetic diversity, and, in the process, genetic drift
74
# Definition:
Founder effect
acute genetic drift that occurs when only a few individuals establish a new population
75
# Definition:
Gene flow
the movement of alleles from one population to another through interbreeding members of each population
76
# Short answer:
What are the examples of non-adaptive mechanisms?
* Genetic drift
* Migration
* Inbreeding
77
# Definiton:
Migration
the movement of organisms from one place to another, including the movement of individuals from one population to another
78
# Defintion:
Inbreeding
mating between close relatives, leading to loss of heterozygosity and increase of homozygosity of rare recessive alleles
79
# Definiton:
Inbredding depression
a reduction in fitness resulting from breeding among close relatives causing homozygosity of harmful recessive mutations
80
# Short answer:
Why, of all evolutionary mechanisms, is selection the only one that can result in adaptation?
Adaptation is the fit between an organism and its environment, only selection causes allele frequencies to change based on how they contribute to the success of an individual in terms of survival and reproductions. Natural selection involves feedback with the environment, whereas genetic drift and other evolutionary forces do not.
81
# Definition:
Molecular evolution
evolution at the level of DNA, which in time results n the genetic divergence of populations
82
# Definition:
Molecular clock
the observation of rate constancy in molecular evolution. The extent of genetic divergence at a gene in two taxa is thus a reflection of the time since the taxa last shared a common ancestor
83
# Defintion:
Pseudogene
a gene that is no longer functional
84
# Short answer:
How is a molecular clock used to determine the time of divergence of two species?
The molecular clock is a region of DNA or protein that has a known rate of accumulation of mutations over time. The more differences we observe when comparing these sequences from two different species, the longer it has been since the species diverged from each other.
85
# Short answer:
Why do we expect a protein’s rate of molecular evolution to be correlated with the protein’s function?
More important proteins would tick slower because they would be less susceptible to change, but a protein that was less necessary would tick faster because it wouldn’t matter if it changed.
86
# Short answer:
What are problems with using gel electrophoresis to measure genetic variation?
It cannot detect synonymous mutations (differences in dna sequences, same amino acid sequence), or mutation that do not affect the mobility of a protein within the gel, and it can only be used with proteins that can be stained or otherwise labelled
87
# Defintion:
Modern Synthesis
the combination of Darwin’s ideas about natural selection and Mendelian genetics
88
# Short answer:
What are the four processes that change allele frequencies (evolution)?
* Mutation
* Genetic drift
* Gene flow
* Natural selection
89
# Definiion:
Allele
version of genes
90
# Definition:
Genotype
combintation of alleles possessed by individuals
91
# Definition:
Phenotype
observable traits
92
# Definition:
Null hypothesis
specifies what should be seen if the hypothesis being tests in NOT correct
93
# Short answer:
What defines fitness?
Reproductive success and adaptations that help one to reach reproductive age
94
# Short answer:
What are the main concepts of mutation as an evolutionary mechanism?
* Ultimate source of genetic variation
* Mutations are random with respect to fitness (beneficial, neutral. deleterious)
* If mutation did not occur, evolution would eventually stop (selection and drift eliminates alleles)
* Bacteria/Archaea: mutation is a significant evolutionary force
* Eukaryotes: mutation alone rarely causes change from genotype frequencies expected under the Hardy-Weinberg principle
* Effect on mutation on populations is relatively slow
95
# Short answer:
What are the main concepts of genetic drift?
* Especially prevalent in small populations, occurs in all
* Causes allele frequencies to drift up and down randomly over time
* Random with respect to fitness, allele frequency changes are not adaptive
* Can lead to the loss/fixation of alleles, genetic variation will decline
96
# Short answer:
What are the main concepts of gene flow/migration?
* Gene flow: movement of alleles from one population to another
* Equalizes gene frequencies between source and recipient populations (homogenise populations, populations start to look like one another)
* Random with respect to fitness
97
# Definition:
Natural Selection
individuals with certain inherited traits survive and reproduce at higher rates than others BECAUSE of those traits
98
# Short answer:
What are the types of nonrandom mating that increases homozygosity?
* Inbreeding
* Assortative mating
* Self-fertilisation
99
# True or False:
Inbreeding results in the change of allele frequencies.
False. Allele frequencies do not change, only genotype frequencies change
100
# Definition:
Inbreeding Depression
high degree of homozygosity exposes deleterious alleles
101
# Definition:
Assortative mating
breeding between individual with similar phenotypes
102
# Definition:
Dimorphism
the condition where sexes of the same species exhibit different morphological characteristics
103
# Short Answer:
What are the main concepts of thetheory, the Fundamental Assymetry of Sex?
* Females should be choosy about mates
* Males will compete for mates
* Alleles that increases male attractiveness or ability to compete should increase in population
* Sexual selection should act more strongly on males than on females
104
# Defintion:
Role Reversal (in the context of sexual selection)
females face stronger competition for mates compared to males
105
# Short Answer:
In what ways does natural selection reduce genetic variation?
* Selecting for thse with highest fitness
* Balancing selection
* Balanced polymorphism
106
# Definition:
Balanced Polymorphism
distribution and the mean stays the same from generation to generation
107
# Short answer:
What are the causes of balanced polymorphism?
* Heterozygote Advantage
* Negative Frequency Dependent Selection
108
# Defintion:
Heterozygote Advantage
heterozygote advantage has higher fitness than homozygous genotypes
109
# Short Answer:
What are the main ideas associated with negative frequency dependent selection?
* Relative fitness associated with different genotypes are not constant, vary with their frequencies in population
* Fitness of a genotype increases as frequency decreases
* Highest fitness when rare
110
# Short Answer:
Consider an allele that increases reproductive success in elephant seal males versus an
allele that increases reproductive success in females. Which allele will increase in frequency
faster, and why?
In elephant seals, it is males that face competition to find a partner. Therefore, I think that the allele that increases reproductive success in males will increase faster, and according to the fundamental asymmetry of sex, sexual selections acts more strongly on males than on females
111
# Short answer:
In the 1700s and 1800s, royalty in Europe often married their close relatives, furtermore,
recessive genetic diseases showed up much more often among royals than the general
population. Explain the likely connection.
The royals practised inbreeding, and it is likely that they fell into an inbreeding depression which led to exposure of deleterious alleles through high homozygosity.
112
# Short answer:
Determine what is wrong about this statement: Black beetles mutated their genes so they
could be brown to avoid predation by birds.
Mutation is random, and adaptation does not occur because organism’s want or need them
113
# Short answer:
Suppose you were studying several species of monkeys. In one, males never helped females raise offspring. In another, males provided just as much parental care as females after the birth of the offspring. How does the fundamental asymmetry of sex compare in the two
species? How would you expect sexual dimorphism to compare between the two species?
The species in which males do not help females raise offspring follows the fundamental asymmetry of sex, and it is likely that the species will have dimorphic traits between the males and females. The other does not follow the theory, and it is likely that males and females look the same/share the same traits/lack dysmorphic traits.
114
# Short answer:
Explain s?y genetic drift leads to a random loss or fixation of alleles?
Genetic drift leads to a random loss or fixation of alleles because it occurs due to chance events in small populations. When a limited number of individuals reproduce, the alleles they carry can be passed on or lost purely by random sampling error. This randomness can cause some alleles to increase in frequency, while others may disappear over time.
115
# Short Answer:
Explain why genetic drift is particularly important as an evolutionary force in small populations
Genetic drift is particularly important in small populations because, in such groups, chance events have a more significant impact on allele frequencies.With fewer individuals, random sampling during reproduction can cause alleles to increase or decrease in frequency by chance alone. This leads to a faster and more pronounced effect of genetic drift in small populations
116
# Short Answer:
f you understand the interaction of mutation and selection, you should be able to explain why deleterious mutations do not cause downward drops in fitness?
Deleterious mutations do not always cause immediate drops in fitness because their effects can be masked by factors such as recessiveness and environmental conditions. Mutations can persist at low frequencies (through selection) without causing a drastic drop in overall fitness.
117
# Short Answer:
Explain the effect of nonrandom mating on allele and genotype frequencies
Inbreeding results in an increased homozygosity in genotypes, but allele frequencies stay the same. Assortative mating and self fertilisation has the same effect. Balancing selection maintains genetic variation, alleles are balances. Sexual selection results in the transmission of certain alleles/traits (increases advantageous allele frequencies).
118
# Short Answer:
Why does inbreeding help “purge” recessive deleterious alleles?
The reduced fitness of homozygous individuals can subject them to stronger natural selection, as they are less likely to survive and reproduce. This increased selection pressure against homozygous deleterious alleles can lead to their removal from the population, effectively "purging" them.
119
# Short Answer:
Explain why males are usually the sex with exaggerated traits used in courtship
Males typically have exaggerated traits in courtship due to the competitive nature of mate selection. These traits serve as signals of genetic fitness and quality, helping males stand out and attract females. Females, with their higher reproductive investment, are often more selective in choosing mates, leading to the evolution of conspicuous male displays and characteristics
120
# Short Answer:
Explain how heterozygote advantage and negative frequency-dependent selection can
maintain genetic variation in populations
Heterozygote advantage and negative frequency-dependent selection maintain genetic variation by favouring the presence of multiple alleles at a gene locus. Heterozygote advantage occurs when individuals with two different alleles have a fitness advantage, while negative frequency-dependent selection occurs when the fitness of an allele or phenotype decreases as it becomes more common. These mechanisms prevent the fixation of a single allele, preserving genetic diversity in populations.
121
# Definition:
Speciation
the process whereby new species are produced
122
# Definition:
Biological species concept (BSC)
species are groups of actually or potentially interbreeding population that are reproductively isolated from other such groups
123
# Short Answer:
What are the cons of the Biological Species Concept?
It cannot be applied to asexual or extinct organisms
124
# Definition:
Morphospecies Concept
* the idea that members of the same species usually look like each other more than other species
* Extended to the molecular level: members of the same species usually have similar DNA sequences that are distinct from those of other species
125
# Short answer:
What are the cons of the morphospecies concept?
members of species may not always look alike (polymorphisms)
126
# Definition:
Cryptic Species:
Species that traditionally were considered to belong to a single species because they look similar, but belong to two species because of differences at the DNA sequence level
127
# Definition:
Hybrid Offspring
The offspring produced by a cross; sometimes applied specifically to interbreeding between two closely related species
128
# Definition:
Ecological Species Concept
* the concept that there is a 1-to-1 correspondence between a species and its niche
* It is impossible for two species to coexist in the same location if their niches are too similar because competition between them for resources inevitable leads to the extinction of one species
129
# Definition:
Niche
a complete description of the role a species plays in its environment and of its requirements, both abiotic and biotic
130
# Definition:
Pholygenetic Species Concept
* the idea that members of a species all share a common ancestry and a common fate
* Ex: species rather than individuals become extinct
131
# Short Answer:
Why has the scientific community been unable to come up with a single, comprehensive, and agreed-upon concept of “species”?
Species change over time, making it difficult to craft a single definition that can be applied in all cases. As well as a species concept must apply to a large range of living and extinct biological forms.
132
# Short Answer:
Why do morphospecies typically correspond to BSC-defined species?
BSC defines species on the basis of the ability to exchange genetic material, if individual share genetic material, they typically look alike.
133
# Short Answer:
What are the types of reproductive isolation?
Prezygotic and Postzygotic
134
# Definiton:
Prezygotic Isolation
isolating factors that prevent the fertilisation of an egg
135
# Definition:
Postzygotic Isolation
describes factors that cause the failure of the fertilised egg to develop into a fertile individual
136
# Short Answer:
What are the examples of prezygotic isolation?
* Geographic isolation: individuals are separated in space
* Ecological isolation: individuals are separated on the basis of where they love or what they don in the environment
* Temporal isolation: individuals are reproductive active at different times
* Behavioural isolation: individuals only mate with other individuals on the basis of specific courtship rituals, song, and other behaviours
* Gametic isolation: incompatibility between the gametes of different individuals
* Mechanical isolation: individuals are unable to mate because of structural incompatibility of genitalia
137
# Short answer:
What are the examples of postzygotic isolation?
* Genetic incompatibility: genetic dissimilarity between two organisms, such as different numbers of chromosomes
* Hybrid inviability: embryo forms but does not fully develop
* Hybrid sterility: offspring are produce but are sterile
138
# Definition:
Partially Reproductive Isolated
populations that have not yet diverges into separate species but who genetic difference are extensive enough for the hybrid offspring they produce to have reduced fertility or viability compared with offspring produced by crosses between individuals within each population
139
# Defintion:
Allopatric Speciation
populations that are geographically separated from each other
140
# Definition:
Subspecies
allopatric population that have yet to evolve even partial reproductive isolation but have acquired population-specific traits
141
# Short answer:
Name and describe the types of alloptric speciation.
* Dispersal: the process in which some individuals colonise a distant place far from the parents
* Vicariance: a geographic barrier arises within a single population, dividing it into two or more populations that are physically separated from each other
142
# Definition:
Perpatric Speciation
a specific kind of allopatric speciation in which a few individuals from a mainland population disperse to a new location remote from the original population and evolve separately
143
# Definition:
Mainlain Population
the central and largest population of a species
144
# Definition:
Island Population
an isolated population
145
# Definition:
Adaptive Radation
a period of unusually rapid evolutionary diversification in which natural selection accelerates the rate of species within a group, resulting in a new species adapted for specific niches
146
# Definition:
Co-speciation
two groups of organism speciate in response to each other and at the same time, producing matching phylogenies
147
# Definition:
Sypatric Speciation
populations that are in the same geographic location
148
# Definition:
Instantaneous speciation
Speciation that occurs in a single generation
149
# Short Answer:
How are genetic divergence and reproductive isolation related to each other?
For populations to genetically diverge from one another, gene flow between them must be limited. One two populations are reproductively isolated from each other, genetic exchange is impossible. Divergence continues after isolation.
150
# Short Answer:
What is the difference between allopatric and sympatric speciation, and which is thought to be more common?
Allopatric speciation occurs after a geographical barrier physically separates two populations from each other while sympatric speciation is the divergence of one group of organisms into two distinct species in the same geographical area. Allopatric speciation is more common since genetic divergence is inevitable between geographically isolated populations.
151
# Short Answer
What is the difference between allopatric speciation by dispersal and allopatric speciation by vicariance?
Dispersal is when a subset of a population moves on its own, while vicariance is when a population is separated by a physical barrier.
152
# True or False:
Nonrandom mating is a strong evolutionary force that often leads to a loss of heterozygotes
False, nonrandom mating is not an evolutionary force as it does not change allele frequencies
153
# Definition:
Taxonomy
science that identifies, names, and classifies new species
154
# Short Answer
Name the nested hierarchy from smallest to largest
* Species
* Genera
* Families
* Ordered
* Classes
* Phyla
* Kingdoms
* Domains
155
# Short Answer:
What are the four criteria to define species?
* Biological species concept
* Morphological species concept
* Ecological species concepts
* Phylogenetic species concept
156
# Short Answer:
What are the main concepts of biological species concept?
* Main criterion: reproductive isolation
* Shortcomings: cannot be applied to fossils, asexual species, and populations that do not overlap geographically
157
# Short Answer:
What are the main concepts of morphological species concept?
* Main criterion: morphological features
* Applicable to sexual, asexual, and fossils
* Shortcomings: polymorphism, cryptic species, subjective features
158
# Short Answer:
What type of organisms does the ecological species concept apply to?
sexual and asexual
159
# Short Answer:
Two species of frog mate in the same pond; one breeds in early summer, and the other in late summer. What type of reproductive isolation is this?
Prezygotic, temporal separation
160
# Short Answer:
What are the 2 ways sympatric speciation occus?
* Host Shift
* Polyploidy
161
# Definition:
Polyploidy
a mutation occurs and the genome duplicates (more than two sets of chromosomes)
162
# Definition:
Autopolyploid
more that 2 chromosome sets from a single species
163
# Definiton:
Allopolyploid
multiple chromosome sets from different species
164
# Definition:
Chromosome alterations
mutations such as inversions, translocations, deletion, duplications
165
# Short answer:
What is the evidence of a fusion event?
* Conservation of gene structure/order
* Common ancestry
166
# Short answer:
What scenarios will occur when isolated populations make contact?
* Reinforcement
* Fusion
* Stability
167
# Definition:
Reinforcement
mechanisms exist that reduces hybridization
168
# Definition:
Fusion:
extensive hybridization removes divergence, (population homogenise)
169
# Definition:
Stability
diverge population with stable hybrid zone
170
# Short Answer:
Which of the following is believed to be the primary reproductive isolation mechanism for causing sympatric speciation in apple maggot flies?
Habitat differentiation / Host Shift
171
# Definition:
Phylogeny
evolutionary history of a group
172
# Definition:
Phylogenetic Tree
simplified diagram of this history
173
# Definition:
Systematics
area of study that characterises and classifies relationships among all organisms
174
# Short answer:
What are the uses of phylogenetic trees?
* Taxonomy: sorting species and taxa
* Medicine: study spread of disease
* Conservations: identify species that are a conservation priority
175
# Definiton:
Node
represents common ancestor for all descendent lineages; a branching point
176
# Definition:
Branch
lineage evolving through time; connects successive speciation events or other branching events
177
# Definiton:
Taxa
end of terminal branches
178
# Definiton:
Clade
a group that includes a common ancestor & all its descendants
179
# Short Answer:
What are the steps of cladistic analysis?
1. Thoughtful identification of homologous characters
2. Choosing an outgroup and coding the character states as either ancestral or derived in a character matrix
3. Grouping by shared derived characters to form the most parsimonious cladogram, producing a hypothesis regarding phylogenetic relationships
180
# Definition:
Character
any genetic, morphological, physiological, or behavioural characteristic to be studied
181
# Short answer:
What are the two character states?
present or absent
182
# Definiton:
Outgroup
closely related to the study group, used to distinguish ancestral vs derived traits
183
# Definition:
Ancestral trait
character that existed in an ancestor
184
# Defintion:
Derived trait
modified form of the ancestral trait, found in a descendant (mutation, selection, drift)
185
# Short answer:
What is the concept of synapomorphies?
* shared derived traits
* found in 2 or more taxa
* Present in most recent common ancestor
* Missing in more distant ancestors
186
# Definition:
Monophyletic groups
included the common ancestor and all descendents of that ancestor
187
# Definition:
Paraphyletic groups
includes the common ancestor and SOME, not all, of the ancestor’s descendants
188
# Definition:
Polyphyletic group
include the common ancestor of the group
189
# Short answer:
What are the possible complicatiosn that may arise when building phylogenetic trees?
* Traits simlar to homolgy or homoplasy/analogy
* Evolutionary reversals
190
# Definition:
Homology
common ancestry
191
# Definition:
Homoplasy/Analogy
convergent evolution, character evolved independently
192
# Definition:
Parsimony
assumes most likely pattern requires the least amount of change (the simplest)
193
# Short Answer:
Propose a scenario explaining how a tetraploid grape plant with extra-large fruit could come from a diploid population with smaller fruit
A spontaneous mutation occurred converting it from a diploid plant to a tetraploid plant
194
# Short Answer:
Explain how a cross between Emmer wheat (tetraploid) and a wild wheat (diploid) gave rise to the hexaploid bread wheat grown throughout the world today
Cross between Emmer wheat (tetraploid) and wild wheat (diploid) led to spontaneous chromosome doubling, resulting in hexaploid bread wheat. This event, known as allopolyploidization, combined the genetic material of both parents.
195
# Short Answer:
Compare the fitness of hybrids in cases where reinforcement occurs versus cases wher
speciation by hybridization occurs
In cases where reinforcement occurs, hybrids typically have reduced fitness. In contrast, in cases where speciation by hybridization occurs, hybrids can exhibit relatively high fitness. Speciation by hybridization is a process where two distinct species merge their genetic material through hybridization, resulting in a new, stable species.
196
# Short Answer:
Sexual selection favours individuals with traits that increase their ability to obtain mates,
such as mating calls in crickets. Using this example, propose a scenario where sexual
selection could contribute to divergence in sympatric speciation
Diverse mating calls, preference for specific calls, reproductive isolation, call divergence, reinforcement, speciation
197
# Short Answer:
Before the application of DNA sequencing of fossils, which species concept was most useful for distinguishing fossils. What is one disadvantage of this approach?
The morphospecies concept was most useful for distinguishing fossils. This concept relied on the physical characteristics and morphological features of fossils to classify them into distinct species. However, this concept does not account for cryptic species, or convergent evolution.
198
# Short Answer:
Are species that branch out later more evolved than species that branch on earlier on a cladogram?
No, both species have been evolving for the same amount of time.
199
# Short Answer:
Which type of homology is useful in building phylogenetic trees? Why is this kind of homology useful and not others?
Synamorphies, because homologies are shared by some and not all
200
# Short Answer:
Why is parsimony commonly favoured in evaluating phylogenetic trees?
The tree requires the fewest changes in character state is the simplest explanation available.
201
# Definition:
Molecular fossils
sterol, bacteria lipid, or some pigment molecule that is relatively resistant to decomposition and can be preserved in sedimentary rocks, documenting organisms that rarely form conventional fossils
202
# Short Answer:
Radiometric Dating
dating ancient material using the decay of radioisotopes as a yardstick
203
# Short answer:
Half-life
the times it takes for an amount of substance to reach half its original values (radiative = decay)
204
# Definition:
Mass extinctions
a catastrophic drip in recorded diversity, which has occurred five or more times in the past 541 million years
205
# Short answer:
What is the significance of Archaeopteryx and Tikaalik?
Archaeopteryx was the fossil organism that illuminates the transition from dinosaurs to birds, while Tiktaalik preserves a stage in the transition from fish to tetrapod.
206
# Short Answer:
How have mass extinctions shaped the ecological landscape?
Mass extinctions have shaped the ecological landscape by removing dominant organisms, thereby changing the competitive dynamic for remaining organisms.
207
# Short answer:
How did the rise of plants help to facilitate the colonisation of land by several different animal groups?
When plants colonised the land surface, they changed the physical character of landscapes, while providing a major source of food for emerging land animals.
208
# Short Answer:
Order the periods of the paleozoic era according to the geological time scale
Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian
209
# Short answer:
What were the major developments in the Paleozoic period?
Cambrian explosion, first terrestrial vertebrates and plants appeared.
210
# Short answer:
What were the major developments of the Mesozoic period?
Age of dinosaurs, first mammals appear, first angiosperms appear
211
