Exam 2 (Ch 7-11)

Question 1

A sub discipline that investigates how allele frequencies and genotype change over time.

Answer 1

Population genetics

Question 2

Given a set of allele frequencies, the expected set of genotype frequencies that will be observed under the HW model.

Answer 2

Hardy-Weinberg equilibrium

Question 3

A measure of strength of natural selection for or against a specific phenotype or genotype.

Answer 3

Selection coefficient

Question 4

When an allele replaces all alternative alleles at the same time; happens when one allele is constantly favored over another; results from underdominance

Answer 4

Fixation

Question 5

A form of selection in which the fitness associated with a trait is not directly dependent upon the frequency of that trait in a population.

Answer 5

Frequency-independent selection

Question 6

A stable equilibrium in which more than one allele is present at a locus.; results from over dominance

Answer 6

Balanced polymorphism

Question 7

Overdominance is associated with…

Answer 7

Heterozygote advantage

Question 8

A form of frequency-independent selection in which heterozygote genotype have higher fitness than the corresponding homozygote genotypes

Answer 8

Overdominance

Question 9

A form of frequency-independent selection in which the heterozygote genotype has a lower fitness than either corresponding homozygote genotype.

Answer 9

Underdominance

Question 10

A measure of the ability to produce offspring

Answer 10

Fecundity

Question 11

An equilibrium frequency of deleterious mutations in which these deleterious mutations are maintained at a positive frequency in a population because of a balance between ongoing deleterious mutation and the purging effect of natural selection

Answer 11

Mutation-selection balance

Question 12

A mating pattern in which individuals with dissimilar phenotypes or genotypes mate with one another.

Answer 12

Disassortative mating

Question 13

When two or more gene copies are identical because of shared descent through a recent common ancestor.

Answer 13

Identical by descent

Question 14

A decrease in fitness that results from individuals mating with genetic relatives

Answer 14

Inbreeding depression

Question 15

A statistical measure of the degree of homozygosity in a population; an inbreeding coefficient

Answer 15

Wright’s F-statistic

Question 16

A population genetic model of evolutionary change in small populations with non-overlapping generations. aka the HW of small populations

Answer 16

Wright-Fisher model

Question 17

Random fluctuation in allele frequencies over time due to sampling effects in finite populations.

Answer 17

Genetic drift

Question 18

Alternative alleles are selectively neutral when there is no fitness difference between them.

Answer 18

Selectively neutral

Question 19

The fraction of individuals in the population that are heterozygous at a given locus

Answer 19

Observed heterozygosity (Ho)

Question 20

The size of an idealized population (no migration, mutation, assortative mating, or natural selection) that loses genetic variation because of genetic drift at the same rate as the population under study

Answer 20

Effective population size

Question 21

A theory developed to study the gene–genealogical relationships in a population by tracing the ancestry of gene copies backward from the present through a finite population.

Answer 21

Coalescent theory

Question 22

The point on a gene tree that delineates the gene copy that is the most recent common ancestor of the genes being studied in a population.

Answer 22

Coalescent point

Question 23

A brief period of small population size. Population bottlenecks reduce genetic diversity and can accelerate changes in allele frequencies due to genetic drift.

Answer 23

Population bottleneck

Question 24

A change in allele frequencies that results from sampling effects that occur when a small number of individuals derived from a large population initially colonize a new area and found a new population. Ex: Manx cat

Answer 24

Founder effect

Question 25

The process by which a species expands into a previously unoccupied area. The individuals colonizing the new area will tend to come from the populations nearest this region, and as a result populations in the newly colonized area will tend to exhibit a reduced genetic relation to those in the source population.

Answer 25

Leading edge expansion

Question 26

The hypothesis that at the molecular level of DNA sequence or amino acid sequence, most of the variation present within a population and most substitutional differences between populations are selectively neutral.

Answer 26

Neutral theory

Question 27

The process in which a new allele arises by mutation and is subsequently fixed in a population.

Answer 27

Substitutions

Question 28

A nonfunctional and typically untranslated segment of DNA that arises from a previously functional gene.

Answer 28

Pseudogene

Question 29

Selection against deleterious mutations.

Answer 29

Purifying selection

Question 30

A technique for assigning relative or absolute age based on genetic data. In their simplest form, molecular clock methods assume that substitutions at neutral loci occur in clocklike fashion, and so researchers use genetic distances between populations to estimate the time since divergence.

Answer 30

Molecular clock

Question 31

The principle that if molecular evolution proceeds at the same constant rate over time in different lineages, all members of a clade should be genetically equidistant from an outgroup to the clade.

Answer 31

Genetic equidistance principle

Question 32

The hypothesis that most polymorphisms and most substitutions, if not strictly neutral, are only mildly deleterious—and that because of relatively small population sizes, natural selection is unable to purge these deleterious variants.

Answer 32

Nearly neutral theory

Question 33

Traits that are affected by many genes simultaneously.

Answer 33

Polygenic traits

Question 34

Genetic contributions to phenotype for a polygenic trait, in which the effects of each allele sum together to determine phenotype.

Answer 34

Additive genetic effects

Question 35

The phenomenon in which alleles at two or more loci interact in nonadditive ways to determine phenotype

Answer 35

Epistasis

Question 36

The range of potential phenotypic variants that could be produced given the current genetic variation in the population, but are not observed because the necessary combinations of alleles are not realized in the population.

Answer 36

Latent variation

Question 37

A haploid set of alleles, i.e., one at each locus

Answer 37

Haplotype

Question 38

The presence of statistical associations between alleles at different loci.

Answer 38

Linkage disequilibrium

Question 39

A measure of nonrandom association between alleles at two different loci. The difference between the actual frequency of a haplotype and the expected frequency of that haplotype if there were no association between alleles at one locus and alleles at the other locus.

Answer 39

Coefficient of linkage disequilibrium

Question 40

Linkage disequilibrium in which the coefficient of linkage disequilibrium D is positive.

Answer 40

Coupling

Question 41

Linkage disequilibrium in which the coefficient of linkage disequilibrium D is negative.

Answer 41

Repulsion

Question 42

A process in which a series of clones carrying beneficial mutations successively go to fixation in an asexual population.

Answer 42

Periodic selection

Question 43

A phenomenon in which a selected allele goes to fixation, carrying with it alleles at physically linked loci.

Answer 43

Selective sweep

Question 44

The process by which a neutral or even disadvantageous allele is able to "ride along" with a nearby favorable allele to which it is physically linked, and thus increase in frequency.

Answer 44

Genetic hitchhiking

Question 45

A process by which neutral or beneficial alleles are lost because they are physically linked to nearby deleterious alleles. Deceases genetic variation relative to what would be expected in a neutral model.

Answer 45

Background selection

Question 46

A source of randomness in the evolutionary process due to the happenstance of the genetic background on which a new mutation arises. Some mutations will rise to high frequency because they arise on a favorable background; others will be lost because they arise on an unfavorable background.

Answer 46

Genetic draft

Question 47

An overall reduction in the rate at which beneficial alleles are fixed in asexual populations due to competition among alternative beneficial mutations.

Answer 47

Clonal interference

Question 48

A heuristic representation of fitness as a function of genotype or phenotype. Commonly used by biologists to envision the course of evolutionary change.

Answer 48

Adaptive landscape

Question 49

Combinations of traits associated with the greatest fitness values on an adaptive landscape.

Answer 49

Fitness peaks

Question 50

Combinations of traits associated with lower fitness values on an adaptive landscape.

Answer 50

Fitness valleys

Question 51

A conceptual model in which similar phenotypes occupy nearby points on a plane. Adaptive landscapes are often illustrated in this type of model.

Answer 51

Phenotype space

Question 52

A conceptual model in which similar genotypes occupy nearby points on a plane

Answer 52

Genotype space

Question 53

A mathematical approach to the population genetic study of continuously varying traits.

Answer 53

Quantitative genetics

Question 54

The fraction of the phenotypic variance that can be attributed to genetic causes of any type and thus is potentially heritable.

Answer 54

Broad-sense heritability (H2)

Question 55

Interactions between two alleles at the same locus in determining phenotype.

Answer 55

Dominance effects

Question 56

The fraction of the total phenotypic variation that is due to additive genetic variation and thus is readily accessible to natural selection.

Answer 56

Narrow-sense heritability (h2)

Question 57

In quantitative genetics, the difference between the mean trait value of the individuals who reproduce and the mean trait value of all individuals.

Answer 57

Selection differential (S)

Question 58

In quantitative genetics, the difference between the mean trait value of the offspring population and the mean trait value of the parental population.

Answer 58

Selection response (R)

Question 59

A technique for identifying the regions of the genome in which quantitative trait loci occur.

Answer 59

Quantitative trait loci mapping (QTL mapping)

Question 60

Loci responsible for quantitative—that is, continuously varying—traits.

Answer 60

Quantitative trait loci

Question 61

Narrow-sense heritability values estimated by using values of the selection differential and selection response in the breeder's equation.

Answer 61

Realized heritabilities

Question 62

What is a common misconception about dominant and recessive alleles that is clarified by the works of Punnett and Hardy?

Answer 62

The misconception is that alleles change in frequency simply because they are dominant or recessive.

Question 63

What relationship does population genetics investigate?

Answer 63

The relationship between the genotype frequencies in an offspring population and a parental population.

Question 64

What are the 5 assumptions of the HW equilibrium?

Answer 64

1. Natural selection is NOT operation on the trait 2. Random mating (not assortative) 3. No mutation 4. No migration into or out of the population 5. Population is infinite in size (genetic drift is negligible)

Question 65

Is sickle cell anemia an example of overdominance or underdominance?

Answer 65

Overdominance

Question 66

The most extreme type of inbreeding is self-fertilization, also called...

Answer 66

Selfing

Question 67

What example was given for disassortative mating?

Answer 67

The white-throated sparrow

Question 68

What was the conclusion for the example given to illustrate disassortative mating?

Answer 68

White-striped (aggressive) females were able to dominate their tan-striped rivals and mate with the tan-striped males; therefore the tan-striped females get left with the white-striped males

Question 69

Does variation within population increase or decrease as a result of natural selection?

Answer 69

Decreases (except in cases of balancing selection)

Question 70

Does variation within population increase or decrease as a result of mutation?

Answer 70

Increases

Question 71

Does variation within population increase or decrease as a result of nonrandom mating?

Answer 71

No effect on allele frequencies (in the absence of sexual selection)

Question 72

Does variation within population increase or decrease as a result of migration?

Answer 72

Increases

Question 73

Does variation between populations increase or decrease as a result of natural selection?

Answer 73

Increases if selective conditions differ, decreases if conditions are the same

Question 74

Does variation between populations increase or decrease as a result of mutation?

Answer 74

Increases

Question 75

Does variation between populations increase or decrease as a result of nonrandom mating?

Answer 75

No effect on all frequencies (in the absence of sexual selection)

Question 76

Does variation between populations increase or decrease as a result of migration?

Answer 76

Decreases

Question 77

What are the three general consequences of genetic drift?

Answer 77

1. In a finite population, allele frequencies fluctuate over time, even in the absence of natural selection 2. Some alleles are fixed other are lost, and the fraction of heterozygotes in the population decreases over time 3. Separate populations diverge in their allele frequencies and in terms of which alleles are present

Question 78

The rate at which allele frequencies fluctuate over time depends on...

Answer 78

The size of the population

Question 79

Does fixation occur quicker in small or large populations?

Answer 79

Small

Question 80

Does genetic drift cause an increase or decrease in heterozygosity?

Answer 80

Decrease

Question 81

The fraction of heterozygotes expected under HW equilibrium.

Answer 81

Expected heterozygosity (He)

Question 82

What example was given to illustrate leading edge expansion?

Answer 82

The Black Spruce species taking over land previously occupied by a glacier

Question 83

What factor contributed to the difference in alleles in the illustration of leading edge expansion?

Answer 83

Seeds (containing nuclear and mt DNA) were distributed locally, and pollen grain (containing only nuclear DNA) were dispersed across long distances; therefore between the populations showed a 10x greater difference in mtDNA than nuclear DNA

Question 84

How old are the microfossils that were discovered in South Africa in 2010?

Answer 84

Approximately 3.2 billion years old

Question 85

How old is the Earth estimated to be?

Answer 85

Approximately 4.5-4.6 billion years old

Question 86

What are the 6 properties if living things?

Answer 86

1. Homeostasis 2. Structural organization 3. Metabolism 4. Growth and reproduction 5. Response to environmental conditions or stimuli 6. Is subject to, and appears to have evolved by, the process of natural selection

Question 87

What does the acronym LUCA stand for?

Answer 87

Last Universal Common Ancestor

Question 88

What does a protocell consist of?

Answer 88

Gene products, nutrients, some sort of membrane for compartmentalization, and genetic material

Question 89

The chemical formation of life from nonliving material

Answer 89

Abiogenesis

Question 90

What chemicals were used in the prebiotic soup hypothesis in 1953 (Stanley Miller)?

Answer 90

Methane, hydrogen and ammonia

Question 91

When two or more molecular substrates each contribute in a positive way to the replication of the other, this is called...

Answer 91

Molecular mutualism

Question 92

Favorable selection would depend on the costs and benefits of ....

Answer 92

Encapsulation

Question 93

What are the 4 benefits of encapsulation?

Answer 93

1. Control of microenvironment 2. Creation of chemical gradients 3. Defense mechanism against predatory replicators 4. Function partitioning

Question 94

What are the distinctions that makes DNA more favorable as the main carrier of genetic information?

Answer 94

1. More chemically stable than RNA 2. Deoxyribose is less reactive than ribose 3. Double-strandedness 4. Proof-reading capabilities 5. Repair mechanisms (using one strand to fix the other that has been damaged) 6. Fewer mutations and longer genes

Question 95

Species concept: a lineage of ... populations which maintains its identity from other such lineages and which has its own evolutionary tendencies and historical fate

Answer 95

The Evolutionary Species Concept

Question 96

What are the 4 most practical and widely used species concepts?

Answer 96

1. Phenetic 2. Biological 3. Ecological 4. Phylogenetic

Question 97

Species concept: draws species boundaries around cluster of phenotypically similar individuals or populations

Answer 97

Phonetic Species Concept

Question 98

Specific way to correlate traits and find commonalities by condensing multiple variables into a single axis

Answer 98

Principle component axis

Question 99

Who first introduced the Biological Species Concept?

Answer 99

Ernst Mayr

Question 100

Species concept: groups of actually or potentially interbreeding populations which are reproductively isolated from other such groups

Answer 100

Biological Species Concept

Question 101

What are three main issues associated with the biological species concept?

Answer 101

1. Doesn't account for extinct organisms 2. Doesn't account for occasional hybridization 3. Doesn't account for asexual species

Question 102

Species concept: a cluster of individuals that occupy the same niche

Answer 102

Ecological Species Concept

Question 103

Species concept: draws species boundaries using shared derived characters that are unique to one monophyletic group and absent from all other populations in the phylogeny

Answer 103

Phylogenetic Species Concept

Question 104

What are the three models of speciation?

Answer 104

1. Allopatric 2. Sympatric 3. Parapatric

Question 105

Model of speciation referring to geographical isolation?

Answer 105

Allopatric

Question 106

Model of speciation referring to populations in which distributions abut one another?

Answer 106

Parapatric

Question 107

Model of speciation referring to populations living in the same location?

Answer 107

Sympatric

Question 108

Allopatric speciation in which 1 large population is divided into 2 still large populations?

Answer 108

Vicariance

Question 109

Allopatric speciation in which the divided populations differing size?

Answer 109

Peripheral isolate

Question 110

What are two factors that could drive sympatric speciation?

Answer 110

1. Resource competition | 2. Reproductive isolation